BANGLADESH ENHANCING COASTAL RESILIENCE IN A CHANGING CLIMATE Swarna Kazi | Ignacio Urrutia | Mathijs van Ledden | Jean Henry Laboyrie | Jasper Verschuur Zahir-ul Haque Khan | Ruben Jongejan | Kasper Lendering | Alejandra Gijón Mancheño BANGLADESH: ENHANCING COASTAL RESILIENCE IN A CHANGING CLIMATE © 2022 International Bank for Reconstruction and Development / The World Bank 1818 H Street NW, Washington, DC 20433 Telephone: 202-473-1000; Internet: www.worldbank.org This work is a product of the staff of The World Bank with external contributions. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, its Board of Executive Directors, or the governments they represent. Although the World Bank and GFDRR make reasonable efforts to ensure all the information presented in this document is correct, its accuracy and integrity cannot be guaranteed. 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Attribution—Please cite the work as follows: Kazi, Swarna, Ignacio Urrutia, Mathijs van Ledden, Jean Henry Laboyrie, Jasper Verschuur, Zahir-ul Haque Khan, Ruben Jongejan, Kasper Lendering, and Alejandra Gijón Mancheño. 2022. Bangladesh: Enhancing Coastal Resilience in a Changing Climate. Washington, DC: The World Bank. Any queries on rights and licenses, including subsidiary rights, should be addressed to World Bank Publications, The World Bank Group, 1818 H Street NW, Washington, DC 20433, USA; email: pubrights@ worldbank.org. Overall Layout and Design: Tasnia Tabassum, Sk. Towhidur Rahaman, Md. Towshikur Rahman, Swarna Kazi. Cover: Designed by Md. Towshikur Rahman and Sk. Towhidur Rahaman using satellite images from ESRI ArcGIS, Maxar, Earthstar Geographics, USDA FSA, USGS, Aerogrid, IGN, IGP, and the GIS User Community. BANGLADESH: ENHANCING COASTAL RESILIENCE IN A CHANGING CLIMATE Swarna Kazi | Ignacio Urrutia | Mathijs van Ledden | Jean Henry Laboyrie | Jasper Verschuur Zahir-ul Haque Khan | Ruben Jongejan | Kasper Lendering | Alejandra Gijón Mancheño TABLE OF CONTENTS FOREWORD ACKNOWLEDGEMENTS STUDY TEAM EXECUTIVE SUMMARY Chapter 3 - Risk Profile 3.1. Tropical Cyclone Flood Risk 96 Chapter 1 - Towards a Resilient Coastal 3.2. Erosion Risk to People, Land, Infrastructure, and Bangladesh Coastal Amenities 104 1.1. A Unique Coastal Zone 33 3.3. Risk of Waterlogging 107 1.2. Success in Creating a Safer and More Inhabitable 3.4. Climate Migration 109 Coast 38 3.5. Concluding Remarks 112 1.3. Rising Risks Due to Climate Change 40 3.6. Notes 112 1.4. Aspirations Towards a Safe, Climate Resilient, and 3.7. References 112 Prosperous Coast 41 1.5. Guidance and Inspiration Towards a More Resilient Coast in Bangladesh 43 Chapter 4 - Empirical Evidence on Selected Coastal Resilience Interventions 1.6. Notes 44 4.1. High-Level Assessment of Coastal Interventions 116 1.7. References 44 4.2. Flood Prevention and Embankments 121 Chapter 2 - Overview and Trends 4.3. Shoreline Stabilization 130 2.1. Coastal Landscape and Dynamics 50 4.4. Cyclone Shelters, Early Warning, Evacuation Roads, and Awareness Raising 141 2.2. Coastal Hazards 76 4.5. Institutions and Policies for Coastal Zone 2.3. Climate and Socioeconomic Change 81 Management 148 2.4. Concluding Remarks 89 151 4.6. Lessons Learned from the Assessment of Past Projects 2.5. Notes 89 4.7. Notes 152 2.6. References 90 4.8. References 152 Chapter 5 - Applying a Risk-Based Approach to Chapter 7 - A Way Forward: Seven Coastal Resilience Recommendations for a More Resilient Coast 5.1. Risk Management Frameworks 158 7.1. Recommendation 1: Strengthen O&M to extract 5.2. Tolerable Risk Guidelines 162 maximum benefits from investments and nurture sustainable interventions 237 5.3. Risk-Informed Planning 166 7.2. Recommendation 2: Embrace the uniqueness of 5.4. Risk-Based Design 173 the Bangladesh coast, recognize local knowledge, strengthen the application of state-of-the- 5.5. Operation and Maintenance 175 art modeling tools and systems, and cultivate knowledge sharing 240 5.6. Notes 179 7.3. Recommendation 3: Apply risk as the guiding 5.7. References 179 principle for adaptative delta management 243 7.4. Recommendation 4: Complement infrastructure Chapter 6 - Building with Nature: Innovative interventions with nature-based solutions to enhance resilience and effectiveness 246 Solutions for Coastal Resilience 7.5. Recommendation 5: Incorporate risk-sensitive 6.1. Polder 35/1: A Hybrid and Nature-Based Solution land-use planning to guide appropriate activities for Combating Erosion 189 based on integrated coastal zone management practices 248 6.2. Kuakata Sea Beach (Polder 48): A Hybrid and Multifunctional Solution for Combating Coastal 7.6. Recommendation 6: Support inclusive community Erosion and Enhancing Tourism 200 participation, local institutions, and livelihoods adaptation for sustainable resilience 254 6.3. Cox’s Bazar: A Hybrid, Nature-Based, and Multifunctional Solution for Combating Coastal 7.7. Recommendation 7: Establish an integrated Erosion, Preventing Flooding, and Enhancing framework of performance criteria of Tourism 208 interventions that goes beyond risk reduction and includes growth, wellbeing, and sustainable Opportunities for Integrating Mangroves in 6.4.  development at its core 257 Coastal Protection Strategies 222 7.8. Coastal Resilience will Support Delta Prosperity 263 6.5. Notes 231 7.9. Notes 264 6.6. References 231 7.10. References 264 Bangladesh: Enhancing Coastal Resilience in a Changing Climate VII TABLES Table 1.1: Report Overview by Chapter 34 Table 2.1: LGED Coastal District Road Network 62 Table 2.2: Changes in the Annual Average Temperature Relative to the 1986 to 2005 Baseline Period per Season for Different Time Horizons and Climate Scenarios 86 Table 3.1: Expected Damages by Asset Type, Baseline and Future Return Period Flood Scenarios 101 Table 4.1: Assessment Criteria and Subcriteria for the Multicriteria Analysis 118 Table 4.2: Coastal Risk Reduction Strategies 119 Table 4.3: Most Significant Projects Selected for In-Depth Assessment 120 Table 4.4: Benefits and Challenges of Preserving the Polder System 125 Table 4.5: Benefits and Challenges of Measures to Combat Coastal Erosion 144 Table 4.6: Meta-Information and Impact Statistics of Defined Cyclone Events in the Pre- and Post-Intervention Periods 147 Table 4.7: Benefits and Challenges of the Effectiveness of Cyclone Shelters and Early Warning Systems 148 Table 5.1: Vietnamese Standards for Sea Dikes 163 Table 5.2: Comparison of Polder 32 Protection Strategies 172 Table 6.1: Considerations for Defining the Hotspots 188 Table 6.2: Present and Future Cropping Intensity in Polder 48 200 FIGURES Figure 1.1: Elevation of Coastal Bangladesh 37 Figure 1.2: World Map of the Global Climate Risk Index Ranking (2000-2019) 38 Figure 1.3: Cyclone Tracks Across the Bangladesh Coastline (1900-2020) 39 Figure 2.1: Shifting of the Main Rivers in Bangladesh over the Last 250 Years 51 Figure 2.2: Delineation of the Four Ecosystem Zones in the Coastal Region 52 Figure 2.3: Location of Embankments that Delineate Polder Boundaries 58 Figure 2.4: Overview of the Road Network in the Coastal Zone 63 Figure 2.5: Walking Distance between Households and Cyclone Shelters 65 Figure 2.6: Coastal Upazilas of Bangladesh by Exposed Coast and Interior Coast 68 Figure 2.7: Population Distribution of the Coastal Upazilas of Bangladesh, 2021 68 Figure 2.8: Primary Employment in the Agriculture (left) and Services (right) Sectors at the Upazila Level 70 Figure 2.9: Rapid Expansion of the Aquaculture Area in the Western Coastal Zone between 1989 and 2010 71 Figure 2.10: Locations of Approved and Planned Special Economic Zones in Coastal Bangladesh 72 Figure 2.11: Tracks of Major Cyclones along Coastal Bangladesh (1685-2020) 78 Figure 2.12: Schematic Overview of Dominant Processes at the Coast Combined with Surface Water Changes Between 1985 and 2016 Reflecting Land Losses and Gains 82 Figure 2.13: Local Displacement Rates in Khulna, February 2017 to December 2019 83 Figure 2.14: Salinity Map of the Coastal Zone indicating Soil Salinity Boundaries for 1973, 2000, and 2009 84 Figure 2.15: Trends in Annual Mean Temperature – Mann-Kendal Test 85 Figure 2.16: Spatial Changes in the Annual Average Precipitation Relative to the 1986 to 2005 Baseline Period for the 2040 to 2059 Time Horizon (left) and the 2080 to 2099 Time Horizon (right) 86 Figure 2.17: Averaged SLR Projections for the 21st Century and Associated Uncertainties 87 Figure 3.1: Land Use of Polder 32 97 Figure 3.2: Clustering of Inundation Levels for Cyclone Flood Risk Analysis 98 Figure 3.3: Inundation Depth Maps for the Baseline and Future Scenarios 99 Figure 3.4: Ratio of Damages per Upazila for the Climate Change Scenario versus the Baseline Scenario 100 Figure 3.5: Estimated Asset Damages per Upazila for the Baseline and Future Storm Surge Scenarios for Different Return Periods, Assuming No Protection 102 Figure 3.6: Aggregate Asset Risk from Cyclone-Induced Coastal Flooding, Baseline and Future Scenario 103 Figure 3.7: Change in the Land Area of Bhola, 2003 to 2015 105 Figure 3.8: Examples of Erosion Hotspots in the Coastal Zone of Bangladesh between 2000 and 2020 108 Figure 3.9: Map of the Polders in the Coastal Zone that Experience Waterlogging Issues 109 Figure 3.10: Predicted Net Migration Numbers by Land-Use Type in 2020 and 2050 for Various Climatic and Socioeconomic Scenarios 110 Figure 4.1: Overview of Methodology for Review of Interventions 117 Figure 4.2: Cascade of Coastal Resilience Strategies 119 Figure 4.3: Key Projects in the Coastal Zone 122 Figure 4.4: Map Showing the Spatial Distribution of the Maximum Flood Depth 126 Figure 4.5: Tidal River Management Conceptual Diagram 131 Figure 4.6: Coastal Erosion in Shandong, China 134 Figure 4.7: Cyclone Shelters in Bangladesh with Construction Date by Color 145 Figure 4.8: Reported Fatalities in Bangladesh and Total Storm Surge Height (tide + surge), 1974-2009 147 Figure 5.1: Schematic Overview of the Key Components of a Flood Risk Management Framework 159 Figure 5.2: Dam Safety Risk Management Framework 159 Figure 5.3: USACE Levee Safety Portfolio Risk Management Process 160 Figure 5.4: International Examples of Societal Risk Guidelines 164 Bangladesh: Enhancing Coastal Resilience in a Changing Climate IX Figure 5.5: Flood Hazard Map for Kyoto City, Minami-ku 167 Figure 5.6: Storm Surge Inundation Maps for 25- and 50-year Return Periods for Bangladesh 168 Figure 5.7: Polders in the Coastal Zone of Bangladesh (left) and a Map of Polder 32 (right) 170 Figure 5.8: Benefit and Cost of Flood Risk 171 Figure 5.9: Plan View of “Hold the Line” Strategy 172 Figure 5.10: Plan View of “Set Back” Strategy 172 Figure 5.11: Plan View of “Differentiating Protection” Strategy 172 Figure 5.12: Japanese Flood Control Measures in Concert with Land Use 173 Figure 5.13: From Tolerable Risk to Calibrated LRFD-based Guidelines 174 Figure 5.14: Design of Slope Protection for the Sea Dike at Biezelingsche Ham in Zeeland, the Netherlands 176 Figure 5.15: The Widening O&M Funding Gap for FCDI Projects 178 Figure 6.1: Overview of the Three Erosion Hotspot Locations for Detailed Analysis 189 Figure 6.2: Land Use in Polder 35/1 190 Figure 6.3: CEIP-I Interventions in Polder 35/1 191 Figure 6.4: Works Undertaken by the CEIP-I in the Bogi Area of Polder 35/1 192 Figure 6.5: Erosion Hotspot, Southeastern Side of Polder 35/1 (left) and Erosion Rates (right) 193 Figure 6.6: Schematic Representation of the Present Situation with Basic Dimensions in Two Cross Sections 193 Figure 6.7: Observed Bed Topography of the Baleshwar River during (from left to right): 2009, 2011, 2015, and 2019 194 Figure 6.8: Proposed Dredging and Dumping Alternatives to Reduce Erosion at Polder 35/1. 196 Figure 6.9: Artist Impressions: Birds-Eye View and Typical Cross Section of Proposed Hybrid Solution 198 Figure 6.10: Works undertaken by CEIP-I adjacent to Kuakata Sea Beach 201 Figure 6.11: CEIP-I Interventions in Polder 48 202 Figure 6.12: Yearly Sediment Transport per Transect Considering only the Wave Climate (including tides) during the SW Monsoon 203 Figure 6.13: Layout of Proposed Interventions at Polder 48, Kuakata Sea Beach 204 Figure 6.14: Cross Section of Interventions at Polder 48, Kuakata Sea Beach: Multifunctional Embankment, Sand Nourishment, and Groynes 205 Figure 6.15: Artist Impression of Kuakata Sea Beach Design for Polder 48 206 Figure 6.16: Artist Impression of a Street View, Kuakata Sea Beach Design for Polder 48 207 Figure 6.17: Location of the Three Sub-Hotspots at Cox’s Bazar and along Marine Drive 211 Figure 6.18: Sub-Hotspot 1: Kolatoli Beach, Cox’s Bazar (during high tide on February 28, 2020) 212 Figure 6.19: Coastal Protection Structures at Kolatoli Beach 212 Figure 6.20: Sub-Hotspot 2: Existing Coastal Protection at Himchori Beach 213 Figure 6.21: Sub-Hotspot 3: Inani Beach 213 Figure 6.22: Cross Section of Proposed Multifunctional Embankment at Kolatoli Beach 214 Figure 6.23: Cross Section of Proposed Interventions at Himchori Beach 214 Figure 6.24: Cross Section of Sand Nourishment Proposal at Cox’s Bazar and Marine Drive 214 Figure 6.25: Intervention Layout of Kolatoli Beach with Sand Nourishment and Multifunctional Embankment 215 Figure 6.26: Artist Impression of a Bird’s Eye View of the Design Proposal for Kolatoli Beach 216 Figure 6.27: Street View Perspective of Multifunctional Embankment at Kolatoli 217 Figure 6.28: Intervention Layout at Himchori Beach: Sand Nourishment and Beautification of Embankment 218 Figure 6.29: Artist Impression of a Bird’s Eye View of the Design Proposal for Himchori Beach 220 Figure 6.30: Artist Impression of a Street View of Himchori Beach 221 Figure 6.31: Nourishment Evolution at Kolatoli Beach (Himchori Beach Shows a Similar Evolution) 222 Figure 6.32: Nourishment Evolution at Inani Beach 222 Figure 6.33: Carbon Stock Densities in the Major Pools by the Forest Zones of Bangladesh 224 Figure 6.34: Spatial Distribution of Damage (percentage of area disturbed) Caused by Three Tropical Cyclones (SIDR, Rashmi, and Aila) Affecting the Sundarbans from 2007 to 2009 225 Figure 6.35: Illustration of Several Mangrove Restoration Techniques 226 Figure 6.36: Wave Reduction through a 100 m-wide Mangrove Belt, Dependent on Incoming Wave Height and Periods 226 Figure 6.37: Design Water Levels (left) and Required Embankment Height (right) with and without Wave Attenuation by a Mangrove Belt (Polder 56/57) 227 Figure 6.38: Steps to Find Potential Sites for Mangrove Afforestation 228 Figure 6.39: Mangrove Establishment Opportunities Along the Coastline of Bangladesh 228 Figure 6.40: (a) Ground Elevation of Java (Indonesia); (b) Map of Mangrove Presence in Indonesia 230 Figure 7.1: The Triple Dividend of Resilience 261 BOXES Box ES.1: Seven Recommendations XXVIII Box 2.1: Delta Morphology 51 Box 2.2: Accessibility of Cyclone Shelters 65 Box 2.3: Measuring Subsidence from Space 83 Box 2.4: Climate Change Projections for Bangladesh 86 Bangladesh: Enhancing Coastal Resilience in a Changing Climate XI Box 3.1: Embankment Breach of Polder 32 97 Box 3.2: Modeling of Cyclone Flood Risk 98 Box 3.3: Bhola Island Change in Land Area 105 Box 3.4: Livelihoods Impacts of Waterlogging 110 Box 4.1: Steps in the Assessment of Ongoing and Historical Projects 117 Box 4.2: Reanalysis of the Effects of Embankment Improvement – A Case Study of Polder 35/1 126 Box 4.3: Maintenance of Embankments Jointly by WMOs and Union Parishads 129 Box 4.4: Tidal River Management 131 Box 4.5: Shoreline Stabilization Practices Around the World 134 Box 4.6: Slope and Foreshore Stabilization using Afforestation and Grass Turfing 140 Box 4.7: Nature-Based Eco-Engineered Coastal Defenses 143 Box 4.8: Reanalysis of the Effectiveness of Cyclone Shelters 147 Box 4.9: Plans and Policies for Disaster Risk Reduction and Climate Adaptation Planning 150 Box 5.1: The Continuous USACE Levee Safety Program Management Process 160 Box 5.2: Public Law as the Basis for Continuous Flood Risk Management in the Netherlands 161 Box 5.3: Risk-Based Flood Protection Standards for Coastal Embankments in Vietnam 163 Box 5.4: Project Appraisal and Optimization 171 Box 5.5: Flood Protection and Resettlement in Japan 173 Box 5.6: Slope Protection Design in the Netherlands 176 Box 5.7: Advances in Monitoring Riverbank Erosion 179 Box 6.1: Combining Green and Grey Nature-Based Solutions in Vietnam’s River Deltas 184 Box 6.2: Multifunctional Embankment “Scheveningen Boulevard” in the Netherlands 185 Box 6.3: Ecosystem Services and Livelihoods Benefits from the Sundarbans Mangrove Forest – Opportunities as a Nature-Based Solution 223 Box 6.4: Forest Carbon Sequestration Opportunities in Coastal Bangladesh 224 Box 6.5: Mangrove Afforestation in Indonesia 229 Box 7.1: Progress within the CEIP-I Long-Term Monitoring and Research Program 241 Box 7.2: The Economic Case for Investments in Climate-Resilient Infrastructure 242 Box 7.3: Putting Nature-Based Solutions into Practice as Part of the CEIP-I 245 Box 7.4: Special Economic Zones and Improved Logistics Services 251 Box 7.5: Examples of Successful Community-Led Bottom-Up Adaptation Projects 253 Box 7.6: Example of Complementary Measures to Make an Intervention Work 259 ACROYNMS AND ABBREVIATIONS ADM Adaptive Delta Management MSL Mean Sea Level ALARP As low as reasonably practicable NAP National Adaptation Plan BCCSAP Bangladesh Climate Change Strategy and Action Plan NAPA National Adaptation Programme of Action BDP 2100 Bangladesh Delta Plan 2100 NDC Nationally Determined Contribution BWDB Bangladesh Water Development Board NGO Nongovernmental Organization CDSP Char Development and Resettlement Project NPDM National Plan for Disaster Management CEIP-I Coastal Embankment Improvement Project Phase I O&M Operation and Maintenance CEP Coastal Embankment Project ODI Overseas Development Institute CZP Coastal Zone Policy PPT Parts Per Thousand DEM Digital Elevation Model PWD Public Works Datum DRR Disaster Risk Reduction RCP Representative Concentration Pathway ECRRP Emergency 2007 Cyclone Recovery and Restoration Project RSLR Relative Sea Level Rise EWS Early Warning Systems SDG Sustainable Development Goal EEWS Erosion Early Warning Systems SEZ Special Economic Zone EU European Union SLR Sea level rise FCDI Flood Control, Drainage and Irrigation SLS Serviceability Limit States FEMA Federal Emergency Management Agency SOD Standing Orders on Disaster FLI Field Level Institution SSP Shared Socioeconomic Pathways GBM Ganges-Padma, Brahmaputra-Jamuna, Meghna TA Technical Assistance GDP Gross Domestic Product TRM Tidal River Management GFDRR Global Facility for Disaster Reduction and Recovery ULS Ultimate Limit States GHG Greenhouse Gas UNDP United Nations Development Programme GoB Government of Bangladesh UNESCO United Nations Educational, Scientific and Cultural Organization GPS Global Positioning System UNFCCC United Nations Framework Convention on Climate Change InSAR Interferometric Synthetic Aperture Radar UNICEF United Nations International Children’s Emergency Fund IWM Institute of Water Modelling UP Union Parishad (Union Council) JICA Japan International Cooperation Agency USACE U.S. Army Corps of Engineers LGED Local Government Engineering Department WMA Water Management Association LRFD Load and Resistance Factor Design WMG Water Management Group LSAC Levee Safety Action Classification WMO Water Management Organization MDSP Multipurpose Disaster Shelter Project WMU Water Management Unit MERIT Multi-Error-Removed Improved-Terrain Bangladesh: Enhancing Coastal Resilience in a Changing Climate XIII GLOSSARY Adaptation: The process of adjustment to actual or expected climate and atmosphere and which is in addition to natural climate variability observed over its effects. In human systems, adaptation seeks to moderate harm or exploit comparable time periods,” thus making a distinction between climate change beneficial opportunities. In natural systems, human intervention may facilitate attributable to human activities altering the atmospheric composition, and adjustment to expected climate and its effects. climate variability attributable to natural causes. Bathymetric map: A map that depicts the submerged topography and Climate risk: The potential for consequences from climate variability and physiographic features of ocean and sea bottoms. change, where something of value is at stake and the outcome is uncertain. It is often represented as the probability that a hazardous event or trend will Bullah: Pilings to build long-lasting stable foundations for structures on land occur multiplied by the expected impact. Risk results from the interaction of and in water. vulnerability, exposure, and hazard. Capital costs: These include all costs incurred up to the completion of a project, Climate scenario: A plausible and often simplified representation of the future including the cost of construction—the costs of material, person hours, land climate, based on an internally consistent set of climatological relationships that acquisition, oversight, planning, and design. has been constructed for explicit use in investigating the potential consequences of anthropogenic climate change, often serving as input to impact models. Char: A sandbar that emerges as an island within a river channel. Climate projections often serve as the raw material for constructing climate scenarios, but climate scenarios usually require additional information, such as Climate: In a narrow sense, usually defined as the average weather of a particular about the observed current climate. location over a period of time. The World Meteorological Organization’s more rigorous definition is “the measurement of the mean and variability of relevant Coastal erosion: The erosion of coastal landforms resulting from wave action quantities of certain variables (such as temperature, precipitation, or wind) over or currents, exacerbated by storm surge and sea level rise. a period of time ranging from months to thousands or millions of years.”1 The usual period for averaging these variables is 30 years. Climate in a wider sense Coastal morphodynamics: The mutual interaction of coastal morphology with is the state, including a statistical description, of the climate system. hydrodynamic agents—tides, currents, and waves. Climate change: It refers to a change in the state of the climate that can be Coastal resilience: Defined in this document as the capacity of the identified (for example, by using statistical tests) by changes in the mean and/or socioeconomic and natural systems in the coastal environment to cope the variability of its properties, and that persists for an extended period, typically with disturbances, induced by both human and environmental factors, while decades or longer. Climate change may be due to natural internal processes or adapting the essential functions of the systems to an improved state. external forces, such as modulations of the solar cycles or volcanic eruptions, or persistent anthropogenic changes in the composition of the atmosphere or Crest: The top part of an embankment. Its elevation in comparison to the in land use. The United Nations Framework Convention on Climate Change, in water level is often a measure of safety. its Article 1, defines climate change as “a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global Earthworks: Operations connected with embankments of earth. Bangladesh: XIV Enhancing Coastal Resilience in a Changing Climate Embankment: An artificial, mostly soil-based structure that is able to retain Maintenance costs: The costs for the upkeep of a structure, including regular water under extreme circumstances. In literature, the terms levee or dike are monitoring, maintenance, repair, operation, and testing. also used. Mangrove: A species of tree that grows in intertidal areas in tropical and Extreme weather event: An event that is rare at a particular place and time of subtropical regions. They attenuate waves and currents, and favor sediment year. Definitions of rare vary, but an extreme weather event would normally be accumulation, which provides coastal protection in landward locations. below the 10th or above the 90th percentile of a probability density function estimated from observations. By definition, the characteristics of what is called Mangrove afforestation: Establishment of a mangrove forest in an area where extreme weather may vary from place to place in an absolute sense. When a there was no previous mangrove cover. pattern of extreme weather persists for some time, such as a season, it may be classed as an extreme climate event, especially if it yields an average or total Mangrove restoration: Return of a mangrove forest from a deteriorated that is itself extreme (for example, drought or heavy rainfall over a season). condition to its previous state, before a devastating natural or human-induced disturbance. Geobag: A sand-filled high-strength geotextile bag. Mitigation (of climate change): A human intervention to reduce the sources Geotube: A geo-container that is hydraulically filled with a slurry mix of sand or enhance the sinks of greenhouse gases. and water. Polder: The Dutch term “polder” is used to designate areas that are enclosed Groyne: A rigid hydraulic structure built from an ocean shore or from a on all sides by dikes or embankments, separating them hydrologically from riverbank that interrupts water flow and limits the movement of sediment. the natural water system and offering protection against tidal floods, salinity intrusion, and sedimentation. Polders are equipped with inlets and outlets to Hazard: The potential occurrence of a natural or human-induced physical control the water inside the embanked area. This is an enclosed low-lying area event or trend or physical impact that may cause loss of life, injury, or other forming an artificial hydrological entity. health impacts, as well as damage and loss to property, infrastructure, livelihoods, service provision, ecosystems, or environmental resources. Resectioning of an embankment: This is done to increase the height and widen the slopes of an existing embankment. It allows for a relatively small change in Hydraulic boundary conditions: A set of values for the water level and the alignment to cope with obstacles and/or to align and smooth transitions with wave height that represent the conditions during a storm, often associated new embankments. with a given return period. Resettlement: Replacement of the asset base and rebuilding of the livelihoods Khal: A small canal. of affected persons losing their land, source of income, or livelihoods because of an infrastructure development project, in the same or a new location. Longshore transport: The cumulative movement of beach and nearshore sand parallel to the shore by the combined action of tides, wind, and waves. Resilience: The capacity of social, economic, and environmental systems to cope Bangladesh: Enhancing Coastal Resilience in a Changing Climate XV with a hazardous event, trend, or disturbance by responding or reorganizing in ways that maintain their essential function, identity, and structure while Storm surge: The increase in the outside water level as a result of storm winds maintaining the capacity for adaptation, learning, and transformation. or a tropical cyclone. Retired embankment: A new embankment with an adequate setback from Tetrapods: A tetrahedral-shaped concrete unit to dissipate wave energy and the riverbank, where bank erosion is threatening the existing embankment. prevent erosion and failure of an embankment or sea dike. This is an embankment that is shifted inland to increase the distance between the embankment and the eroding bank line and as such, creates a buffer zone Union: The smallest rural administrative and local government unit in against future erosion. Bangladesh. Each union is made up of nine wards, comparable to a village. A union parishad administers a union, formed under the Local Government Return period: The average period of time between two events. Often used (Union Parishads) Act 2009. as a measure for the intensity of a natural event (for example, a 10-year storm, occurring on average once every 10 years). Upazila: An administrative region of Bangladesh that functions as a subunit of a district, or a subdistrict. Rural upazilas are further administratively divided Scenario: A plausible description of how the future may develop based on a into union council areas. coherent and internally consistent set of assumptions about key driving forces (for example, rate of technological change, prices) and relationships. Note that Vulnerability: The propensity or predisposition to be adversely affected. scenarios are neither predictions nor forecasts but are useful to provide a view Vulnerability encompasses a variety of concepts, including sensitivity or of the implications of developments and actions. susceptibility to harm and lack of capacity to cope and adapt. Sea level rise: The increase in the height of the sea with respect to a specific point on land. Notes 1. “FAQs Climate,” World Meteorological Organization (website), accessed November 20, 2021, https://public.wmo.int/en/about-us/frequently-asked-questions/climate. Bangladesh: XVI Enhancing Coastal Resilience in a Changing Climate Source: NASA Earth Observatory (Cyclone Amphan 2020) Bangladesh: Enhancing Coastal Resilience in a Changing Climate XVII S M Mehedi Hasan Bangladesh: XVIII Enhancing Coastal Resilience in a Changing Climate FOREWORD As the World Bank and Government of Bangladesh celebrate 50 years of development cooperation this year, a key highlight is the journey towards addressing climate change and improving the resilience of the coastal zone. From the outset, the World Bank has been a long-standing partner in the Government’s efforts to reduce the risks from disasters and enhance coastal resilience, resulting in a number of noteworthy achievements. Bangladesh demonstrated how investments in the entire chain of disaster risk reduction saves lives, reduces economic losses, and protects development gains. Proactive policies and sound investments in strengthening resilience across multiple fronts over the last five decades have resulted in a drastic decline in the number of casualties from cyclones. Bangladesh’s approach has been an integrated one, from grassroots strengthening of community-level adaptation and community-based early warning systems, to investing in key protective infrastructure and promoting innovations, all founded on a strategic policy framework. With the success of these initiatives, Bangladesh has emerged as a global leader in climate resilience. Although there has been significant progress, with the coastal population and economy expected to grow, and the intensity and magnitude of extreme events projected to increase due to climate change, hazard impacts still pose a great threat to the development ambitions of the country. Thus, further actions are needed to improve the resilience of the coastal zone. The Bangladesh: Enhancing Coastal Resilience in a Changing Climate report provides new perspectives and insights into how to address the impacts of climate-related hazards in the coastal zone. The report provides evidence of the drivers of risks in Bangladesh’s coastal zone, analyzes what has been achieved so far in reducing these risks, and reviews the lessons learned from these achievements. Supported by in-depth analytical work, the report explores innovative solutions illustrated with artist impressions and puts forward seven key recommendations to enhance coastal resilience in Bangladesh and build shared prosperity for decades to come. What is clear from the report is that investing in coastal resilience will bring multiple benefits, and that the time to act is now. Mercy Tembon John A. Roome Bernice K. Van Bronkhorst Country Director Regional Director Global Director Bangladesh and Bhutan South Asia Sustainable Development Urban, Resilience and Land Global Practice The World Bank The World Bank The World Bank Bangladesh: Enhancing Coastal Resilience in a Changing Climate XIX ACKNOWLEDGEMENTS This report was prepared by a team led by Swarna Kazi (Senior Disaster Risk Towhidur Rahaman, S. M. Mehedi Hasan, Mohammad Rafiqul Islam, Olivia Management Specialist), Ignacio Urrutia (Senior Disaster Risk Management Moutusi Sarker, Amani Haque, Partha Protim Nath, Mohammad Abdul Basit, Specialist), Mathijs van Ledden (Senior Disaster Risk Management Consultant), Dewan Rakibul Islam, Md. Rakibul Islam, Asif Aminur Rashid, Maherul Kader Jean Henry (Harrie) Laboyrie (Managing Director, Delta Context), Jasper Prince, Souptik Barman Tirtha, Sanjana Sayannita, Md. Moinul Islam, Sanjoy Verschuur (DPhil Candidate, University of Oxford), Zahir-ul Haque Khan (Deputy Roy, Kazi Shahanewaz Hossain, Sharif Mukul, Steven Newman, Allan Hsiao, Executive Director, Institute of Water Modelling), Ruben Jongejan (Technical Ella Kim, Stephanie Tam, Marc Forni, Dzung Huy Nguyen, Suranga Kahandawa, Consultant), Kasper Lendering (Technical Consultant), and Alejandra Gijon Deepak Singh, Anup Karanth, Keiko Sakoda, Masood Ahmad, Maria Sarraf, Mancheno (Postdoctoral researcher, Delft University of Technology). Abedalrazq Khalil, Anna O’Donnell, Steven Rubinyi, Yoko Okura, Sachi Suzuki, Tom Schwantje, Olivia Becher, Julian Gonzalo Jimenez, Md. Akhtaruzzaman, The report was produced under the overall guidance and leadership of Abhas Chaohua Zhang, Jun Zeng, Sabah Moyeen, Sanjay Srivastava, Esra Arikan, K. Jha (Practice Manager, Climate Change and Disaster Risk Management, Sharlin Hossain, Nadia Sharmin, Iqbal Ahmed, S. M. Zulkernine, Md Istiak South Asia Region), John A. Roome (Regional Director, South Asia Sustainable Sobhan, Josefo Tuyor, Takeaki Sato, Marcelo Acerbi, Jorge Luis Alva-Luperdi, Development), Bernice K. Van Bronkhorst and Sameh Naguib Wahba (current A.N.M. Mustafizur Rahman, Hasib Ehsan Chowdhury, Kai Xin Nellie Teo, Marie and former Global Director, Urban, Resilience and Land Global Practice). Florence Elvie, and Rosemary Birungi Kyabukooli. The team gratefully acknowledges contributions from technical experts Alexia The team would like to thank Mercy Tembon (Country Director, Bangladesh and Sotiriadou, Marcel Marchand, Alessio Giardino, Kees Bons, Shristi Vaidya, Mark Bhutan) for her inspiration and infinite encouragement. The team would also de Bel, Steven te Slaa, Bas van de Sande, Bart Peerbolte, Herald Vervoorn, Kun like to recognize Dandan Chen (Operations Manager), Gayatri Acharya (Sector Yan, Tim Leijnse, Abu Saleh Khan, Malik Fida A. Khan, Md. Saiful Islam, Md. Leader, Sustainable Development), Ikechi B. Okorie (Sr. Operations Officer), Shahadat Hossain, A.F.M. Afzal Hossain, S. M. Mahbubur Rahman, Rubayat Asna Zareen (Operations Officer), and Mohammad Azad Rahman (Operations Alam, Tarun Kanti Majumdar, Sarwat Jahan, Md. Sohel Masud, Tarek Bin Hossain, Officer) of the Bangladesh Country Management Unit for their continuous Shume Akhter, Upal Mahmud, Md. Mainul Islam, Md. Raqibul Hasib, Sarazina guidance and support. Mumu, Kamrul Hassan, Benzir Hoque Mou, Sanjay Gupta, Erik van Berchum, Bas Jonkman, Wim Kanning, and Peter Herman. Analytical work informing The team gratefully acknowledges the peer reviewers and advisers Nathan this report included input from the firms and individual experts contracted Engle (Senior Climate Change Specialist), Nadia Sharmin (Senior Environmental by the World Bank: Delta Context, Deltares, CDR International, Institute of Specialist), Alanna Simpson (Lead Disaster Risk Management Specialist), Marc Water Modelling (IWM), Center for Environmental and Geographic Information Forni (Lead Disaster Risk Management Specialist), and Thomas Kerr (Lead Services (CEGIS), Delft University of Technology, and University of Oxford. Climate Change Specialist) for their insightful and constructive comments, which helped to improve the report. The team appreciates the support from the World Bank team of staff and consultants who have contributed to the coastal resilience program in This report was prepared as a result of a unique collaborative exchange with Bangladesh, comprising Debashish Paul Shuvra, Md. Towshikur Rahman, Sk. the Government of Bangladesh, and the study team would like to thank the Bangladesh: XX Enhancing Coastal Resilience in a Changing Climate many officials for their support, feedback, and guidance, including (not in order International Centre for Climate Change and Development (ICCCAD) for the of seniority) Senior Secretary, Ministry of Water Resources, Senior Secretary, overall guidance and inspiration Ministry of Local Government, Rural Development, and Cooperatives, Secretary, Ministry of Environment, Forest and Climate Change, Secretary, Ministry of The team is thankful for the guidance from External Affairs, including Elena Planning, Secretary, Ministry of Finance, Mr. Fazlur Rashid (Director General, Karaban, Mehrin Ahmed Mahbub, Mehreen Arshad Sheikh, Shilpa Banerji, and Bangladesh Water Development Board (BWDB)), Mr. Sk. Md. Mohsin (Chief Mohammad Kaium. Engineer, Local Government Engineering Department (LGED)), Mr. Md. Abdur Rashid Khan (Retired Chief Engineer, LGED and Ex-Project Director Emergency The team kindly acknowledges Tasnia Tabassum, Md. Towshikur Rahman, and 2007 Cyclone Recovery and Restoration Project (ECRRP)), Mr. Sarafat Hossain Sk Towhidur Rahaman, for leading the overall publication layout and graphics Khan (Retired Director General WARPO & Ex-Project Director, Coastal design and S M Al Mahmud for producing the accompanying video for this Embankment Improvement Project Phase-I (CEIP-I), BWDB), Mr. Md. Habibur report. The team also appreciates the highly skillful editorial services provided Rahman (Retired Additional Director General & Ex-Project Director Coastal by Veronica Suozzi. Embankment Improvement Project Phase 1 (CEIP-I), and Ex-Project Director, ECRRP, BWDB), Mr. Syed Hasan Imam (Project Director CEIP-I, BWDB), and Mr. The team thanks the collaborative partnerships in coastal and climate resilience Javed Karim (Project Director, Multipurpose Disaster Shelter Project, LGED). The with the Japan International Cooperation Agency, Embassy of Japan, Embassy team is thankful for the views and feedback shared by the institution/agency of the Kingdom of the Netherlands, and the Global Center on Adaptation. officials/academia/key experts who attended the stakeholder consultations and the numerous discussions and exchanges. Lastly, the team would like to thank the Global Facility for Disaster Reduction and Recovery (GFDRR) for its generous support. This report has been made The team would like to extend its appreciation to Mr. Abul Kalam Azad (Former possible by funding from the GFDRR-managed trust funds: the Japan–World Special Envoy, Climate Vulnerable Forum Presidency and Former Principal Bank Program for Mainstreaming Disaster Risk Management in Developing Secretary to the Hon. Prime Minister of Bangladesh), Mr. Saber Hossain Countries, Coastal Resilience: Developing New and Innovative Approaches in Chowdhury, Member of Parliament and Chair of Parliamentary Standing Bangladesh, financed by the Government of Japan, and with financial support Committee on Ministry of Environment, Forest and Climate Change, Professor from the European Union (EU) in the framework of the EU-South Asia Capacity Ainun Nishat, Professor Emeritus, Centre for Climate Change and Environmental Building for Disaster Risk Management Program, Informing the New Generation Research (C3ER), BRAC University and Professor Saleemul Huq, O.B.E., Director, of Investments and Policies for Coastal Resilience. Bangladesh: Tapash Paul Enhancing Coastal Resilience in a Changing Climate XXI STUDY TEAM SWARNA KAZI is a Senior Disaster Risk Management Specialist at the World Bank. She is responsible for strengthening country partnerships, managing the policy dialogue, leading operations, and analytics, to advance the climate change and disaster risk management agenda. Swarna manages a portfolio of over US$1.5 billion of high priority, climate and disaster resilience, fragility and conflict, emergency preparedness and response, multi-sector operations. She has worked with the World Bank for over 15 years, initially joining in 2002. Prior to her current position, Swarna was based in London, working as an Evidence and Policy Advisor in the U.K. Government, Ministerial Department for Environment, Food & Rural Affairs (Defra). Swarna has an academic background in Environmental Science and Water Resources Management. She completed the course work for an MSc. in Water Resources Development from Bangladesh University of Engineering and Technology. Swarna is a Chevening Scholar and obtained an MSc. degree in Water Science, Policy, and Management from the University of Oxford (Christ Church College). IGNACIO URRUTIA is a Senior Disaster Risk Management Specialist at the World Bank currently working in the South Asia Region where he leads lending and technical assistance projects with a focus on coastal and urban resilience, resilient infrastructure, fragility and conflict, emergency preparedness and response, post- disaster reconstruction, and climate change. Prior to South Asia, Ignacio worked in the Water, Urban, and Disaster Risk Management unit in the Latin America and the Caribbean region. He holds an MPA in Development Practice from Columbia University. MATHIJS VAN LEDDEN is a Senior Disaster Risk Management Consultant at the World Bank. He is involved in programs related to flood risk reduction across the globe, including, Bangladesh, Vietnam, Serbia, Suriname, Guyana, Mozambique, Liberia, and the Democratic Republic of Congo, where he oversees analytics and Bank operations from a technical perspective. From 2003 to 2017, he was with the global consultancy, Royal HaskoningDHV, he worked on projects in flood- prone areas such as rivers and coasts. After Hurricane Katrina in 2005, Mathijs supported the US Army Corps of Engineers New Orleans District with the 100-year levee design. Mathijs also held a position at Delft University of Technology and was previously a Senior Disaster Risk Management Specialist at the Global Facility for Disaster Risk Reduction and Recovery (GFDRR). Mathijs graduated in Hydraulic Engineering from Delft University of Technology, followed by a PhD at the same university. Mathijs has many publications in peer-reviewed journals. JEAN HENRY (HARRIE) LABOYRIE is a Coastal, Port, and River Engineer with 40 years-experience working in over 40 countries. He is currently Managing Director and owner of Delta Context. Harrie previously held the positions of Partner of CDR International, Director Global of the Business Line “Rivers, Deltas & Coasts” at Royal HaskoningDHV. Prior to that he worked as a researcher at Institute for Applied Research at Delft Hydraulics (now Deltares) and Maritime Research Institute Netherlands (MARIN). Harrie’s field of expertise and areas he has been active include structures, revetments and groynes, rehabilitation of coastal defence works, ports, inland waterways, shipping, river morphology, bank protection, soil conservation, water management, shipping, master planning, economic studies, institutional strengthening, feasibility studies, and leading design and supervision of large-scale infrastructure projects. Harrie holds an MSc. in Coastal Engineering from the Delft University of Technology and MBA certificates in Management and Finance from INSEAD Fontainebleau. Harrie has been continuously involved in disaster risk management and water related projects in Bangladesh since 1991. JASPER VERSCHUUR is a DPhil candidate at the Environmental Change Institute, University of Oxford. Jasper’s research focuses on quantifying economic impacts from climate extremes and natural disasters to infrastructure systems. In particular, he develops new modelling frameworks to quantify present and future supply-chain losses due to infrastructure disruptions at a global scale. Jasper has worked on research projects ranging from quantifying climate impacts to food security, coastal erosion and household welfare. Alongside his PhD, he is a Sustainable Development Fellow for the World Bank in the South Asia Climate Change and Disaster Risk Management Unit. Jasper holds a BSc and MSc in Civil Engineering from Delft University of Technology and an MSc in Water Science, Policy and Management from the University of Oxford. Bangladesh: XXII Enhancing Coastal Resilience in a Changing Climate ZAHIR-UL HAQUE KHAN is a leading Coastal Zone Management Specialist in Bangladesh. He has over 37 years of experience in coast, estuary, port, and river engineering, with experience in South Asia and East Asia. Zahir is currently Deputy Executive Director (Operation) Institute of Water Modelling (IWM), Director IWM Malaysia and previously led the Coast, Port and Estuary Management division of IWM as a Director for 18 years. He worked for the preparation of the Bangladesh Delta Plan 2100 and served as the focal point of the Integrated Coastal Zone Management program (ICZMP). Zahir has vast experience in the study of flow dynamics, waves, storm surges, erosion, flood and drainage management, impact assessment of climate change and sea level rise, numerical, hydrological, hydrodynamic, and morphological modeling. He has led many feasibility studies and prepared over 40 technical reports in the field of integrated water resources management and climate change. Zahir holds a BSc in Civil Engineering and M. Engg. in Water Resources Engineering from the Bangladesh University of Engineering and Technology. RUBEN JONGEJAN is an independent consultant with his firm Jongejan Risk Management Consulting and a technical consultant for the World Bank. He works on flood risk management projects around the world, including the Netherlands, USA, Australia, Sri Lanka, and Bangladesh. Over the past 15 years, Ruben has played an active role in the development and introduction of new flood protection standards as well as the application of new design guidelines for flood defences. Ruben is a member of the Netherlands Commission for Environmental Assessment (NCEA) and the Dutch Expertise Network for Flood Protection (ENW). He has served on various expert panels, such as the 2019 International External Review Panel that reviewed the risk policies and methodologies for dam safety of the U.S. Army Corps of Engineers, Bureau of Reclamation, and the Federal Energy Regulatory Commission in response to legislative direction from the US Congress. While Ruben mainly works in the field of flood protection, he also supports the Dutch government in managing the risks from induced seismicity in the northern Netherlands. Ruben has (co) authored many peer-reviewed articles and several flood protection (design) guidelines, including the Dutch Fundamentals on Flood Protection. Ruben obtained BSc, MSc (hons.) and PhD in Hydraulic Engineering from Delft University of Technology, and BA and MA degrees (hons.) in Political Science from Leiden University. KASPER LENDERING is an independent consultant with his firm AWA-Consult and a technical consultant for the World Bank. He specializes in flood risk management, structural engineering, and contract management. Prior to opening his firm, Kasper worked as a consultant with Horvat & Partners in the Netherlands, where he advised the government on (probabilistic) cost estimates, quantitative risk analyses and asset management of public infrastructure. Since 2013, Kasper has been involved in a research team led by the Delft University of Technology, to aid with the design of a Coastal Barrier in Houston, Texas. Kasper also works as a Construction Manager for the construction of a hospital facility which is designed to sustain 200mph winds and earthquake loads in the Caribbeans. Kasper graduated with a BSc and MSc in Hydraulic Engineering from Delft University of Technology followed by a PhD in flood risk management from the same university. ALEJANDRA GIJÓN MANCHEÑO is a postdoctoral researcher at Delft University of Technology. She is involved in projects related to mangrove restoration and the design of hybrid coastal solutions, which combine coastal vegetation with conventional structures like dikes. Alejandra graduated in Hydraulic Engineering cum laude at Delft University of Technology in the Netherlands in 2016 followed by a PhD at the same university in close cooperation with Deltares and Witteveen+Bos. During her PhD, Alejandra investigated mangrove restoration at the eroding coastline of Demak (Indonesia), where she conducted two field campaigns between 2017-2018. She also performed laboratory analyses and modelling work, in parallel to mentoring and teaching. Alejandra has carried out analytical work for the World Bank, in 2020 and 2022, where she investigated the potential for mangrove afforestation in Bangladesh. Her scientific work has been published in peer-reviewed journals and presented at several international conferences such as AGU (2021). Bangladesh: Enhancing Coastal Resilience in a Changing Climate XXIII EXECUTIVE SUMMARY Coastal Bangladesh, fringed by the Bay of Bengal and home to The Bangladesh: Enhancing Coastal Resilience in a Changing Climate report over 40 million people, is a dynamic, unique, and thriving environment full of seeks to provide actionable guidance for enhancing coastal resilience based opportunities. However, multiple risks are also at play, as the coast of Bangladesh on in-depth analytical work supported by the World Bank. The work included sits on the frontlines in the battle against climate change. Among the most extensive stakeholder consultations, expert interviews, field visits, data analysis, climate-vulnerable and disaster-prone countries in the world, Bangladesh, and numerical modeling, with the aim of contributing to the design of particularly the coastal zone of Bangladesh, is experiencing setbacks in its sustainable climate-resilient coastal investments. The target audience of this development because of natural hazard impacts. Tropical cyclones and floods report is intentionally broad, encompassing those at the strategic, operational, are frequently recurring events, while coastal and riverine erosion and salinity and technical levels, from decision makers to practitioners, and all those who intrusion are chronic phenomena affecting millions of people each year along have an interest in the Bangladesh coast or are involved in programs to increase the coast. its resilience against natural hazards. Protecting lives, livelihoods, and assets from disasters has been central to Overall, this report: Bangladesh’s development strategy, with the Government of Bangladesh (GoB) • Summarizes the key lessons from past interventions, which can guide the headlining impressive progress in making the coastal zone safer over the last design for the next generation of coastal resilience programs; several decades, highlighted by a hundred-fold decline in fatalities from cyclonic • Takes a deep dive into how Bangladesh can adopt a more risk-based events. Taking an integrated approach, Bangladesh instituted policies and legal strategy following international best practices; and frameworks, enhanced systems and institutions, led hydrometeorological and • Provides inspiration for what future interventions oriented towards more forecasting advancements, and supported communities and community-based nature-based solutions could look like. early warning systems, while also investing in critical infrastructure, such as cyclone shelters, coastal embankments, water management infrastructure, Seven cross-cutting recommendations pave the way forward and offer an alongside afforestation initiatives. The result has been a drastic decrease in opportunity to strengthen the resilience of the coastal zone and build shared mortality, people affected, and overall losses from hazard impacts. prosperity for decades to come. As Bangladesh celebrates 50 years since Independence, the country is A unique coastal environment facing increasing natural risks recognized for proactively investing in disaster risk reduction and is considered a global leader in climate resilience. However, a rapidly growing population, Bangladesh’s physical characteristics as well as the livelihoods of its people environmental degradation, socioeconomic development, and climate change are defined by the Ganges-Padma, Brahmaputra-Jamuna, and Meghna (GBM) are putting pressure on the existing natural and infrastructure systems in the delta, which is one of the largest, most populated, active, and dynamic deltas coastal zone. The ability to continue the ongoing rapid economic growth hinges in the world. Endowed with an abundance of natural resources, the coastal critically on how hazard impacts are managed, and resilience is built into the zone is controlled by the dynamic interaction between the influx of water and economy and natural environment. sediments, coastal processes such as tide and wave action, episodic events such as cyclones and monsoon rainfall, ecological processes, and human interventions (Chapter 2). The dynamic behavior of the delta is an ever evolving Bangladesh: XXIV Enhancing Coastal Resilience in a Changing Climate and complex process of nature adapting to constantly changing conditions at insufficient drainage, lack of adequate maintenance of water infrastructure, and different temporal and spatial scales. Hence, uncertainties are prevalent and reduced river flow from upstream. As all hazards have distinct spatial footprints, large, yet efforts should be made to quantify and better understand them. localized information is needed to perform risk analyses, including ways to capture these complex local characteristics in models to predict the evolution The coastal zone faces several risks, which are shaped by the interaction of of these hazards in the future. the spatial occurrence of natural hazards with the unique natural and human environment (Chapter 3). Overall, the most threatening hazards in the Evidence of success of coastal resilience interventions coastal zone, which include cyclones, storm surges, erosion, salinity intrusion, waterlogging, and coastal flooding, are significant and are likely to increase The GoB has made significant strides towards implementing and scaling-up over time, both in frequency and intensity, as a result of changing climatic a wide variety of coastal resilience interventions, covering both structural and conditions. This will affect people, livelihoods, critical infrastructure, social and non-structural interventions, and in developing the country’s legal, regulatory, ecosystem services, the environment, and the economy. and policy frameworks. An illustration of this is that since Independence, about US$10 billion has been invested in disaster risk management and preparedness The average annual losses from tropical cyclones alone were recently estimated in the coastal zone. Given the significant additional investments needed, it to be about US$1 billion (0.7 percent of gross domestic product (GDP)) (Ozaki is imperative to learn from past experiences to evaluate the effectiveness of 2016). However, individual cyclone events can result in larger losses. The two interventions and identify key focal points to guide future investments plans. tropical cyclones that have led to the largest losses on record in Bangladesh This report provides a first-of-its-kind screening exercise of all large investment are Cyclone Sidr (2007, upper estimate of US$3.8 billion in losses) and projects since the 1960s, after which a certain number of projects were selected Cyclone Gorky (1991, upper estimate of US$3.0 billion in losses) (Ozaki 2016). for in-depth analysis (Chapter 4). Furthermore, new analytics presented in this report find that at present, 27 percent of the coastal population is exposed to a 100-year coastal flood event, The reanalysis of the effectiveness of the coastal polders showed that they which is expected to increase to 35 percent in the future as a result of a rise of have a large positive benefit-cost ratio given their aim of reducing risk and half a meter in the sea level. The risk to assets is about US$300 million per year boosting agricultural production. Despite their success, challenges remain with at present and will almost double in size because of sea level rise (SLR) alone. respect to proper operations and maintenance (O&M) of the infrastructure, Alongside an increase in coastal flooding, SLR will push saline water further into resettlement and land acquisition, and erosion. In terms of combating coastal the tidal channels, threatening agricultural production, water supplies, and the and riverine erosion, the traditional approach has been to build either temporary diversity of coastal ecosystems. measures or hard engineering solutions. These measures can be effective but can also be expensive and require intensive maintenance. Softer nature-based Large parts of the coastal zone also face significant erosion, both along the solution approaches have also been implemented through the conservation coast and in the tidal channels. Within the tidal channels, over the last 30 years, and reforestation of mangrove forests throughout the coastal zone, which help river migration rates from 50 meters up to 500 meters have been observed, in stabilizing shorelines while simultaneously providing sustainable community threatening the stability of large stretches of embankments and the people and livelihoods opportunities and biodiversity benefits. livelihoods protected within them. Waterlogging is present, which can cause long-lasting disruptions (social, physical, and environmental) and result in Alongside measures to directly prevent hazard impacts, approximately 5,000 income loss and social unrest. Often a range of drivers are the cause, including multipurpose disaster shelters provide safe havens during cyclonic conditions, Bangladesh: Enhancing Coastal Resilience in a Changing Climate XXV many of which serve as schools during normal times. In addition, advancements Water Act. However, the legal basis for sustainable funding, continuous have been made with respect to early warning systems, the development of monitoring, maintenance, and rehabilitation of infrastructure assets is still awareness programs for safe evacuation, and community-based disaster risk needed in Bangladesh. management and preparedness, for instance through the flagship Cyclone Preparedness Programme, which consists of a large corps of community • Program level: A risk management framework facilitates the movement volunteers. These initiatives have significantly reduced the losses suffered from from a more reactive response with regards to risk management to one cyclone impacts. that is more continuous and forward-looking that allows the incorporation of uncertainty. The GoB has made steps towards this by endorsing a Finally, significant development has been made on the strategic front by shared vision within the Bangladesh Delta Plan 2100, which helps with creating a comprehensive set of policies, plans, and strategies that recognizes the prioritization of risk management actions and the design of future that climate change, disaster risk, and broader development objectives go hand programs. However, strategies to translate this vision into practice, for in hand and should be addressed in tandem. In particular, the Bangladesh Delta instance by creating tolerable risk thresholds and a risk-based project Plan 2100 provides a policy document that stimulates long-term planning, prioritization, should be developed over the years to come. while emphasizing flexible decision-making in view of uncertainties related to present and future risks, towards a Delta Vision of “achieving a safe, climate • Implementation level: Thinking in terms of risk can help optimize resilient and prosperous delta.” the design of interventions and prioritize investments in the most cost- efficient way. For instance, as part of the new analytics undertaken, Risk as a guiding principle for action in Bangladesh alternative polder designs show that by differentiating protection levels across the polder, higher benefit-cost ratios can be achieved compared A key lesson learned from reviewing past interventions is that Bangladesh could to the current designs. Similarly, implementing probabilistic, or risk-based, benefit from a more intentional and structured application of a risk management design guidelines could cut costs by optimizing the design of infrastructure framework for planning, designing, and maintaining coastal resilience systems. interventions (Chapter 5). Risk management frameworks are particularly suitable for dealing with the many uncertainties planners face in terms of Given the vast extent of infrastructure in Bangladesh, any improvements in the climate change and socioeconomic development, which are sometimes hard risk management framework will pay off and ensure long-term sustainable risk to quantify given the deep uncertainties. The report includes international best financing. This does require, however, a coordinated set of actions across the practices in risk management and how these can support efforts to improve policy, program, and implementation levels. coastal resilience. A comparison of these best practices with the current way of working in Bangladesh has revealed areas where risk management can add Innovative solutions for coastal resilience value on three levels: Another key lesson learned from the past interventions is that there is significant • Policy level: A risk management framework can help direct and control potential in Bangladesh for nature-based solutions or a mix of green-grey the actions of different organizations in a coordinated manner. This needs infrastructure (hybrid solutions) (Chapter 6). Hybrid solutions are increasingly to be supported by a clear institutional structure with associated duties recognized as feasible alternatives in Bangladesh and help conserve natural and responsibilities for water management, as outlined by the Bangladesh resources while protecting communities. Several such innovative hybrid Bangladesh: XXVI Enhancing Coastal Resilience in a Changing Climate solutions are explored in this report, all of which were developed based on Moving towards a more resilient coast extensive stakeholder consultation, field visits, and numerical modeling. These solutions are also compared to the solutions implemented to date to This report provides new perspectives and innovative insights to address the understand the added value but also the potential implementation challenges. impacts of climate-related hazards in the coastal zone (Chapter 7). Although Bangladesh has made significant steps towards reducing the vulnerability of • For Polder 35/1, a hybrid approach of dredging and bank protection has the coastal zone, significant residual risks remain, and these risks will only been proposed that can cost-efficiently help resolve the erosion problem increase with socioeconomic development and climate change. To achieve the polder faces. The analysis indicates that dredging an additional channel Bangladesh’s aspiration to become a safe, sustainable, and resilient delta, seven in the river and disposing of the sediment at the erosion hotspot will key recommendations (Box ES.1) with specific short-, medium-, and long-term naturally reduce the pressure on the existing bank protection. actions are suggested. • At Polder 48 (Kuakata) and Himchori Beach, Kolatoli Beach, and Inani Beach (along the Cox’s Bazar-Teknaf Marine Drive Road), all existing or 1. Strengthen O&M to extract maximum benefits from investments and upcoming tourist hotspots, a multifunctional system that includes a beach nurture sustainable interventions. nourishment in combination with an embankment has been proposed to reduce the retreat of the coastline, minimize the impacts of flooding, and Solid O&M of all existing natural and human-made structural and non- provide an attractive beachfront for tourism purposes. structural assets is the foundation of coastal resilience. Investments in O&M activities and organizations should be prioritized to ensure that existing key • The restoration of mangrove forests for coastal protection purposes has assets provide their essential services to coastal communities. These include been assessed since mangroves have proven to be effective at reducing protecting communities and economic activities against the impacts of coastal wave run-up. An analysis of the suitability of mangrove afforestation sites hazards. The Bangladesh Delta Plan 2100 recommends that 0.5 percent of GDP across the coastal zone shows that there are approximately 600 kilometers be allocated for O&M of water management infrastructure compared to the 0.1 of coastal stretches suitable for natural colonization. For example, by percent invested at present. combining mangroves with existing or new embankment systems, the required embankment height may be reduced, which would potentially 2. Embrace the uniqueness of the Bangladesh coast, recognize local decrease the direct cost of raising the embankments and the required knowledge, strengthen the application of state-of-the-art modeling footprint. tools and systems, and cultivate knowledge sharing. The initial results provide valuable evidence that such hybrid interventions The unique landscape and dynamics of coastal Bangladesh requires a thorough can be cost effective, potentially lowering the upfront costs of infrastructure understanding of the functioning of the present system in order to predict interventions, albeit with potentially higher maintenance requirements and how future scenarios in coastal environmental conditions might change, as a enhanced monitoring needs. Still, the flexibility and wider co-benefits of whole, and what that means in terms of the design of interventions. Continuous such interventions make them attractive alternatives for coastal resilience in development of knowledge and implementation of state-of-the-art modeling Bangladesh. tools and technical guidelines should be prioritized, including knowledge transfer of these developments. The long-term monitoring and research Bangladesh: Enhancing Coastal Resilience in a Changing Climate XXVII Box ES.1: Seven Recommendations program under the Coastal Embankment Improvement Project Phase I (CEIP-I) can act as an excellent step in this direction. Strengthen operation & maintenance to extract 01 3. Apply risk as the guiding principle for adaptive delta management. maximum benefits from investments and nurture sustainable interventions. Given the changing climate and dynamic coastal processes of Bangladesh’s coastal zone, adaptive delta management (ADM) should be the cornerstone Embrace the uniqueness of the Bangladesh of any attempt to achieve coastal resilience. ADM is about flexible decision- 02 coast, recognize local knowledge, strengthen the application of state-of-the-art modeling tools and systems, and cultivate knowledge sharing. making in view of the uncertainties related to present and future risks. A risk management approach is well-suited to inform decisions about public safety given large uncertainties, and could help tie together strategic planning, design, and O&M, further improving the efficiency and effectiveness of coastal interventions in Bangladesh. 03 Apply risk as the guiding principle for adaptive delta management. 4. Complement infrastructure interventions with nature-based solutions to enhance resilience and effectiveness. Complement infrastructure interventions with The natural environment provides an excellent opportunity to reduce risk while 04 nature-based solutions to enhance resilience and effectiveness. providing valuable services to society. Hybrids of traditional infrastructure with nature-based solutions, like sediment solutions and mangrove restoration for protection against cyclones and erosion, should be pursued in future programs. Developing and monitoring pilot projects are important for learning from best Incorporate risk-sensitive land-use planning to guide practices and developing guidelines for the implementation of such solutions 05 appropriate activities based on integrated coastal zone management practices. in different parts of the coastal zone. 5. Incorporate risk-sensitive land-use planning to guide appropriate activities based on integrated coastal zone management practices. Support inclusive community participation, 06 local institutions, and livelihoods adaptation for sustainable resilience. Changes in land-use and socioeconomic characteristics will shape the composition of the coastal zone in terms of what is at risk, where, and how. Given the longevity of investment horizons, risk-sensitive land-use planning should be at the core of coastal zoning policies. Risk-sensitive land-use Establish an integrated framework of performance 07 planning can take place on different scales and should be based on various criteria of interventions that goes beyond risk reduction and includes growth, wellbeing, and plausible land-use and socioeconomic scenarios, contingent on the changing sustainable development at its core. environmental conditions. Such scenarios not only help in testing the robustness Bangladesh: XXVIII Enhancing Coastal Resilience in a Changing Climate of interventions but can also inform migration policies and policies for the As coastal resilience efforts are often aligned with ongoing development spatial allocation of present and future economic activity. efforts, it is important to ensure that development objectives are well integrated into these efforts to reap the large gains that can be made from adapting 6. Support inclusive community participation, local institutions, and to a changing climate while also achieving the United Nations Sustainable livelihoods adaptation for sustainable resilience. Development Goals. Alternative policy evaluation frameworks should be developed that explicitly take development objectives into consideration Strengthening the adaptive capacity of coastal livelihoods ensures that coastal alongside wider planning efforts to align different program objectives in order inhabitants have the ability and means to make a living under the various to benefit from positive cross-sectoral spillovers. shocks and stressors they face. However, before such efforts can be scaled- up and mainstreamed into national adaptation plans, a systematic framework Bangladesh is currently at a crossroads. A do-nothing scenario would inevitably should be established that can track the development of adaptation efforts in overwhelm the coping capacity of the coastal zone in a changing climate and communities and investigate drivers for, and barriers to, success. Furthermore, socioeconomic landscape. Nonetheless, this report makes clear that there local institutions with a diverse representation of social groups, upgraded is ample opportunity to invest in coastal resilience that will bring multiple capacity, sufficient resources, and clear roles and responsibilities should be benefits in terms of avoided losses, wider economic benefits, and social and established or strengthened to make sure efforts are sustainable. environmental benefits, and presents an opportunity to shift Bangladesh’s trajectory from one of vulnerability to resilience and prosperity. 7. Establish an integrated framework of performance criteria of interventions that goes beyond risk reduction and includes growth, References wellbeing, and sustainable development at its core. M. 2016. “Disaster Risk Financing in Bangladesh.” SSRN Electronic Journal 46. doi: Ozaki,  10.2139/ssrn.2941319. J. H. Laboyrie Bangladesh: Enhancing Coastal Resilience in a Changing Climate XXIX TOWARDS A RESILIENT COASTAL BANGLADESH 1.1. A Unique Coastal Zone 1.2. Success in Creating a Safer and More Inhabitable Coast 1.3. Rising Risks Due to Climate Change 1.4. Aspirations Towards a Safe, Climate Resilient, and Prosperous Coast 1.5. Guidance and Inspiration Towards a More Resilient Coast in Bangladesh 1.6. Notes 1.7. References 30 Bangladesh: Enhancing Coastal Resilience in a Changing Climate 1 Swarna Kazi CHAPTER 1: TOWARDS A RESILIENT COASTAL BANGLADESH For Bangladesh, situated in the most dynamic and populated delta in the world, which dwells in the world’s largest mangrove forest, the Sundarbans, a coastal coastal resilience is fundamental to its existence, development, and prosperity. sanctuary to both Bangladesh and India and an ecosystem of global ecological The coastal zone of Bangladesh2 covers an area of 47,201 square kilometers (32 significance. Coastal urban areas include Chattogram, an industrial seaport and percent of the country) (Ahmad 2019) and is inhabited by approximately 43.82 the second largest city after Dhaka, the capital of Bangladesh. Coastal port cities million people (around 26 percent of the population).3 Fertile sedimentary soil and urban hubs are strategic gateways for economic growth and development, has enabled the widespread adoption of agriculture, while large intertidal zones with Bangladesh being located between global powerhouses India and China. are home to a diverse array of flora and fauna, including the Royal Bengal tiger, However, the coastal zone of Bangladesh, with its wealth of natural resources Chapter 1: Towards a Resilient Coastal Bangladesh 31 and economic opportunities, also faces significant risks, including coastal for the end of the 21st century. The coastal zone is one of the identified BDP hazards, such as cyclones, sea level rise (SLR), salinity intrusion, and erosion, 2100 hotspots, where both climate-related challenges and socioeconomic and the challenges associated with them. These hazards are expected to occur development converge. Coastal resilience is the cornerstone of achieving more frequently in a changing climate, which could permanently affect the a safe, resilient, and prosperous delta, and defined here as “the capacity of life and livelihoods of coastal inhabitants. Shifting socioeconomic conditions the socioeconomic and natural systems in the coastal environment to cope and community preferences add to the overall uncertainty in planning for the with disturbances, induced by both human and environmental factors, while future. The adverse but also uncertain impacts of climate change and extreme adapting the essential functions of the systems to an improved state.” The weather events threaten an evolving coastal Bangladesh as it continues to concept is inherently linked to objectives such as poverty reduction, climate develop and could further hinder development gains and the economic growth adaptation, and achieving the United Nations Sustainable Development Goals of the nation and impede the development pathway of the regional economy. (SDGs). Recognizing this, the Government of Bangladesh (GoB) developed the Moreover, coastal resilience is not a static goal to be met, but rather a continuous Bangladesh Delta Plan 2100 (BDP 2100) with the tagline: “Achieving a safe, process of adapting to changing conditions and finding synergies between climate resilient and prosperous delta” (General Economics Division, Bangladesh different development objectives. It requires on the one hand a forward-looking Planning Commission 2018). This plan provides a long-term vision of the delta approach to understand the various pathways the coastal zone may take, and Mahfuzul Hasan Bhuiyan Mathijs van Ledden Standing on the frontlines in the battle against climate change in coastal Bangladesh. Bangladesh: 32 Enhancing Coastal Resilience in a Changing Climate the challenges and uncertainties associated with those pathways. On the other risks, i.e. embankments, erosion protection, disaster shelters, and mangroves. hand, it necessitates looking back at past efforts that have enhanced resilience Other aspects, such as drainage infrastructure, road networks, or housing, are to learn from and identify best practices. Furthermore, coastal resilience involves touched upon in relation to these main systems. Based on the findings and an integrated framework for decision-making towards achieving development analysis, seven recommendations for deepening coastal resilience options outcomes. It means working together with an informed understanding of are presented with proposed strategic actions to strengthen the ambition of integrated coastal zone management and partnering in emerging sectors resilient coastal development. and innovations. It is based on a process of broad inclusive participation to answer the key questions of what the desired outcomes are and for whom, The target audience of this report is intentionally broad, as increasing coastal what the roles and responsibilities of the different stakeholders are, how to resilience requires an integrated effort involving various types and levels of find the requisite resources, how to achieve the intended outcomes, and what stakeholders and organizations, from the decision makers to the practitioners, the timeline is. in areas ranging from policy and planning, finance and economics, technical analysis and engineering, to social and environmental safeguards. Bringing The objective of this report is to provide actionable guidance and inspiration together interdisciplinary insights in one report contributes to the mutual for more resilient coastal interventions in Bangladesh through summarizing exchange of expertise and information on coastal resilience. Table 1.1 provides and integrating various pieces of analytical work supported by the World Bank. a summary of the contents of the chapters of the report. Each chapter starts Its value added is that it summarizes key lessons learned for the design of future with a brief introduction and outline of the remainder of the chapter, which can coastal programs based on a comprehensive review of past interventions. In guide the reader to chapters that are of specific interest to them in terms of addition, it takes a deep dive into how Bangladesh can adopt a more risk-based their scope. strategy following international best practices and what future interventions with more of an orientation towards nature-based solutions could look like. 1.1. A Unique Coastal Zone An improved understanding of what a more resilient coast might look like is The coastal zone of Bangladesh spans over 710 kilometers along the Bay of essential for the planning, design, and implementation of future interventions. Bengal and is part of one of the largest, youngest, and most active deltas in The report provides evidence of the drivers of risks in Bangladesh’s coastal zone, the world. The zone is located at the downstream end of the three great trans- analyzes what has been achieved so far in reducing these risks, and reviews Himalayan rivers—the Ganges-Padma, the Brahmaputra-Jamuna, and the the lessons learned from these achievements. Supported by in-depth analytical Meghna (GBM)—and is the world’s largest sediment dispersal system (Akter work, interviews with experts, stakeholder consultations, and site visits, the et al. 2016). While over 90 percent of the GBM catchment area lies outside report explores innovative solutions illustrated with artist impressions and puts of Bangladesh, over 400 rivers and tributaries of the GBM drain through the forward a series of concise recommendations to enhance coastal resilience in country via a constantly changing network of rivers, tidal inlets, and tidal creeks, Bangladesh. before discharging into the Bay of Bengal (Bangladesh Water Development Board (BWDB) 2020). Since coastal resilience is a broad subject with multiple dimensions, this report can only cover a portion of this topic and is not an exhaustive narrative. Bangladesh’s physical and cultural characteristics as well as the livelihoods of The focus of the analytical work has been primarily through a lens on water its people are defined by the GBM delta, which is endowed with an abundance infrastructure systems and their associated interactions to reduce coastal of natural resources. The southwestern part of this coastal zone hosts the Chapter 1: Towards a Resilient Coastal Bangladesh 33 Table 1.1: Report Overview by Chapter Chapter 1: Towards a resilient coastal Bangladesh These chapters provide a systematic overview and diagnosis. Chapter 1 is an introduction to the setting, the concept of coastal resilience, its relevance Chapter 2: to sustainable development, and a framework towards achieving coastal Overview and trends resilience. Chapters 2 and 3 present a description of the coastal zone and its Chapter 3: infrastructure and summarizes a coastal-wide risk assessment based on the Risks profile latest data. Chapter 4 hones in on past interventions in the coastal zone and the lessons learned from these interventions. Chapter 4: Empirical evidence on selected coastal resilience interventions Chapter 5: These chapters aim to advance the knowledge of and insights into the areas Applying a risk-based approach to coastal resilience that have been identified in the preceding chapters. Chapter 5 focuses on the added value of a more risk-based approach and Chapter 6 presents Chapter 6: inspirational examples of how a more nature-based approach towards coastal Building with nature: innovative solutions for coastal resilience interventions in the context of Bangladesh may look like in practice. Chapter 7: This final chapter provides seven recommendations with concrete actions on A way forward: seven recommendations for a more resilient coast how to increase coastal resilience in Bangladesh. Sundarbans mangrove forest, which is the largest mangrove ecosystem in the coast. It hosts a vast system of sandy beaches and dunes, such as in Cox’s Bazar, world, covering an area of approximately 10,000 square kilometers, about 60 home to one of the longest sandy beaches in the world. These are important percent of which is within Bangladesh’s territory, with the remainder in India. areas for tourism, biodiversity, and recreational purposes. Fishing, agriculture, This World Heritage site is known for its extensive range of exquisite flora and shrimp farming, and salt farming are the traditional main economic activities fauna, with over 330 floral species, and a wide variety of wildlife, including of the coastal communities throughout the entire coastal area (Hossain et al. the Royal Bengal tiger, the national animal of Bangladesh. The Sundarbans 2016), although industrial manufacturing and the service sector have grown welcomes more than 250,000 national and international tourists every year, and quickly over the last couple of years. green sustainable coastal tourism is a potential service sector for the growing economy. The coastal zone is continually affected by fluctuations of the GBM river system as well as regular coastal processes such as tidal propagation, salinity intrusion, The southwest and central parts of the coastal zone consist of vast tracts of and erosion. The Global Climate Risk Index ranks Bangladesh as the seventh low-lying, fertile land often surrounded by embankments and separated by most affected country in the world over the 2000 to 2019 period (Figure large tidal water systems (see Figure 1.1). The eastern part of the coastal zone 1.2), with an average of 577 casualties and US$1.6 billion in losses every year is a relatively narrow strip of land with a series of hills running parallel to the (Eckstein, Künzel, and Schäfer 2021). Damages and losses associated with a Bangladesh: 34 Enhancing Coastal Resilience in a Changing Climate S M Mehedi Hasan The Sundarbans mangrove forest. single extreme event impose substantial costs on the national economy and very intense cyclones. With 62 percent of the coastal land having an elevation can set back the achieved development gains multiple years. of less than three meters above MSL (Bangladesh Water Development Board 2013), the potential for cyclone-induced inundation is widespread. The average Records from 1990 to 2014 show that over 90 percent of casualties and 40 annual losses from tropical cyclones alone have recently been estimated at percent of economic damage in Bangladesh are related to storms, with severe approximately US$1 billion (0.7 percent of gross domestic product (GDP)) cyclone events contributing the most to the reported damages (CRED 2021). based on risk modeling (Ozaki 2016, Table 10). However, individual cyclone Cyclones, which are accompanied by powerful winds, heavy rainfall and large events result in larger losses. The two tropical cyclones4 that have led to the storm surges, are a regular phenomenon and pose a serious threat to coastal largest losses on record are Tropical Cyclone Sidr (2007, upper estimate of communities along the entire coastline (Figure 1.3). On average, about one US$3.8 billion in losses) and Tropical Cyclone Gorky (1991, upper estimate of cyclone makes landfall every year, striking the funnel-shaped and relatively US$3.0 billion in losses) (Ozaki 2016, 3). shallow northern portion of the Bay of Bengal—a perfect natural amplifier— raising the water level more than 10 meters above mean sea level (MSL) during Chapter 1: Towards a Resilient Coastal Bangladesh 35 M Abdullah Abu Diyan A Royal Bengal tiger in the Sundarbans. Bangladesh: 36 Enhancing Coastal Resilience in a Changing Climate Figure 1.1: Elevation of Coastal Bangladesh Source: Map developed by the World Bank for this report based on data from Humanitarian Data Exchange, the World Bank, ESRI ArcGIS, Maxar, Earthstar Geographics, USDA FSA, USGS, Aerogrid, IGN, IGP, and the GIS User Community. Chapter 1: Towards a Resilient Coastal Bangladesh 37 Other more gradual and less visible hazards in the coastal zone are salinity observed of about 45 meters on average over the last 30 years, but up to 500 intrusion (Dasgupta et al. 2015), erosion (World Bank 2021), subsidence (Brown meters in some places (Jarriel et al. 2020), threatening bank protection works. and Nicholls 2015), and waterlogging (Alam et al. 2016). Salinity intrusion in the surface water system and in the soil from tidal propagation into low- The impacts of the various threats are not equally distributed among households. lying coastal plains contribute to the risk of drinking water shortages (which Continuous exposure to both episodic (cyclones) and chronic (salinity, are predominantly from groundwater sources), the spread of water-related subsidence) hazards can push the country’s poor further into poverty. The diseases, and irrigation water shortages, which can impact food security poor are often forced to live in at-risk areas, thereby being disproportionately and lead to the loss of employment opportunities for agricultural workers. exposed to hazards (Hallegatte et al. 2020), while also lacking the ability to Additionally, hundreds of kilometers of the coastal shoreline experience some cope and recover from the adverse impacts (Akter and Mallick 2013; Hallegatte degree of erosion. The continued retreat of the coastline poses a threat to the and Rozenberg 2017). stability of embankments and further results in significant losses of valuable arable land. This is also true for the tidal and river channels, with migration rates 1.2. Success in Creating a Safer and More Inhabitable Coast The development of a safe and inhabitable coastal zone has long been a Figure 1.2: World Map of the Global Climate Risk Index Ranking (2000-2019) priority for Bangladesh. Compelled by increasing demand for food, intensive rice cultivation was promoted in the 1960s during the Green Revolution through the construction of a series of coastal polders (areas that are enclosed on all sides by dikes or embankments, separating them hydrologically from the natural water system, in which the water table is managed), which protected polder inhabitants from tidal flooding and salinity intrusion. The polders have proven to act as a first line of defense by effectively protecting people and crops from the adverse impacts of cyclones. The need for these investments in terms of risk reduction was clearly highlighted by Cyclone Bhola in 1970, one of the deadliest disasters on record, which resulted in about 300,000 lives lost per official estimates (Ministry of Disaster Management and Relief 2010), with unofficial estimates being significantly higher. Following this disaster, the GoB, with the support of donor partners, invested over US$10 billion towards the development of structural (flood protection infrastructure, cyclone shelters, cyclone-resistant housing) and non-structural (early warning and awareness- raising systems) disaster mitigation and preparedness systems. Over the past several decades, the GoB has demonstrated that investments in the entire chain of disaster risk reduction (DRR) can save lives, reduce economic losses, and protect development gains. The number of casualties resulting Source: Eckstein, Künzel, and Schäfer 2021. from cyclones has dropped a hundred-fold over the last five decades due to Bangladesh: 38 Enhancing Coastal Resilience in a Changing Climate Figure 1.3: Cyclone Tracks Across the Bangladesh Coastline (1900-2020) Source: Map developed by the World Bank for this report based on data from Humanitarian Data Exchange, United Nations Environment Programme, Bangladesh Meteorological Department, and the World Bank. Chapter 1: Towards a Resilient Coastal Bangladesh 39 successful efforts on multiple fronts such as improved early warning systems while extreme poverty declined from 34.3 percent to 12.9 percent (Bangladesh (EWS), increased access to a network of cyclone shelters and evacuation roads, Bureau of Statistics 2016). While this downward trend is mirrored in the coastal and awareness raising through a large-scale organized volunteer program (the zone, poverty indicators show an above-average poverty incidence in the Cyclone Preparedness Programme) (BDRCS, n.d.) and associated community- coastal zone (Akter and Mallick 2013). In particular, extreme poverty persists in based initiatives for disaster preparedness and response. the most at-risk areas near the coast (Dasgupta et al. 2021), where households disproportionally rely on natural resources that are degrading fast and are With the coastal embankment system, there has been a reduction in coastal more vulnerable to hazard impacts. flooding and a boost in agricultural production in Bangladesh, with initial productivity increases of up to 200 to 300 percent in certain areas (Nishat 1.3. Rising Risks Due to Climate Change 1988). Softer nature-based solutions have also been implemented through the conservation and reforestation of mangrove forests throughout the coastal Climate-change-induced changes in the frequency and intensity of extreme zone, which have helped in stabilizing shorelines while providing sustainable events and chronic stressors can have major, and sometimes irreversible, co-benefits to communities. implications for coastal livelihoods, the environment, and the provision of infrastructure services. Rising temperatures, which lead to more intense and These interventions have contributed to a considerable improvement in the unpredictable rainfalls during the monsoon season and a higher probability of living conditions of the coastal communities of Bangladesh. The national catastrophic cyclones, are expected to result in increased inundation. On top poverty rate fell from 48.9 percent to 24.3 percent between 2000 and 2016, of this, the coastal zone is recognized as one of the most at-risk areas globally Mahfuzul Hasan Bangladesh: Bhuiyan 40 Enhancing Coastal Resilience in a Changing Climate due to SLR (Hooijer and Vernimmen 2021). The combination of SLR and the and climate change strategies. It developed the Bangladesh Climate Change ongoing subsidence can elevate storm surges and push saline waters further Strategy and Action Plan (BCCSAP) and National Adaptation Programme of into tidal channels. It is estimated that a 1-meter rise in sea levels would result Action (NAPA) in 2009 (Ministry of Environment and Forests 2009)5 to respond to in a loss of land of more than 4,800 square kilometers (roughly 3.2 percent of climate-change-induced development risks, and the National Plan for Disaster the country) (Rigaud et al. 2018), making a large part of the delta unsuitable Management (NPDM) for 2010-2015 (Ministry of Disaster Management and for agricultural production due to elevated salinity concentrations (Dasgupta Relief 2010) to put in place sound DRR measures and respond to disasters. Since et al. 2015). then, the NPDM has been updated twice, with the NPDM 2016-2020 (Ministry of Disaster Management and Relief 2017) and the NPDM 2021-2025 (Ministry On the one hand, socioeconomic development will further exacerbate the of Disaster Management and Relief 2021). Similarly, the Second Perspective coastal risks in the coming decades. The coastal population is projected to Plan of Bangladesh 2021-2041 (General Economics Division, Bangladesh grow to 61 million by 2050 (Mainuddin and Kirby 2015), resulting in an increase Planning Commission 2020) emphasizes that managing climate change and in the exposure of people and assets. The increasing population, the loss of implementing the BCCSAP is essential to achieving the vision of transforming valuable land, and the climatic impacts to coastal livelihoods will likely result in the national economy. climate migration away from the coastal zone, as indicated in a recent World Bank study (Rigaud et al. 2018), although it is expected that a large share of In 2018, the GoB approved the BDP 2100 (General Economics Division, the population, including the most impoverished, will remain in this vulnerable Bangladesh Planning Commission 2018), a techno-economic, water-centric, area. Therefore, this study calls for the development of coastal zone strategies long-term vision and action plan. The BDP 2100 seeks to integrate the medium- to adapt the coastal environment to accommodate “stay in place” areas that to long-term aspirations of Bangladesh to achieve upper middle-income status are relatively safe and provide sustainable livelihoods opportunities. and eliminate extreme poverty by 2030, and to become a prosperous country beyond 2041, with the longer-term challenge of sustainably managing the On the other hand, the economy of the coastal zone is expected to transition country’s water, ecology, environment, and land resources in the context of to become more diversified, with large welfare improvements. To ensure their interaction with natural disasters and climate change. It looks primarily at sustainable social and economic development in this area, climate-related and the delta agenda up to 2050 and takes into account that decisions taken today socioeconomic risks in the coastal zone and their inherent uncertainties need have implications for 2050 and beyond. The plan sets out a long-term vision to be addressed. This will require both structural solutions and non-structural for the evolution of the Bangladesh delta with the aim to be “a safe, climate solutions, such as diversification of income and employment, financial resilient, and prosperous delta” by the end of the 21st century and defines short- protection systems, and access to finance. and medium-term goals as steps to reach that vision. This vision is associated with around a US$37 billion investment plan (covering 80 projects), financed 1.4. Aspirations Towards a Safe, Climate Resilient, and Prosperous by both the public and private sectors. These goals, associated strategies, Coast policies, institutions, and investments are moving targets and are intended to be adaptive in nature to shift track if needed, given the large uncertainties. Bangladesh aspires to eliminate extreme poverty and become a middle-income Alongside the BDP 2100, Bangladesh initiated the National Adaptation Plan country by 2030, and a prosperous country beyond 2041. To this end, the GoB (NAP) to fill the gap of institutional arrangements alongside a coordinated has recognized the need to intensify efforts in coping with climate-related strategy for mid- and long-term climate change adaptation investments (UNDP challenges. Over the years, it has instituted DRR plans, legal frameworks, 2017). The objective is “to formulate the Bangladesh National Adaptation Plan Chapter 1: Towards a Resilient Coastal Bangladesh 41 Asif Aminur Rashid Bangladesh: 42 Enhancing Coastal Resilience in a Changing Climate with a focus on medium to long term adaptation investments and enhance synergies between both can also be identified and utilized, for instance by national capacity for integration of climate change adaptation in [the] planning, enhancing the ability of the natural system to buffer against extreme events and budgeting and financial tracking process.” To achieve this, an estimated provide valuable livelihood opportunities (for example, mangroves, beaches). US$5.7 billion per year will be needed by 2050 in terms of adaptation finance, which is more than five times the current spending on adaptation (Ministry of As Bangladesh further develops, the challenge of coastal management is to Environment, Forest and Climate Change 2021). balance the needs of both the socioeconomic and natural coastal systems in the near- and long-term future, and to increase the resilience of both (Masselink A common thread in these strategies and action plans is the ubiquitous call and Lazarus 2019). Coastal resilience is a continuum, and at the heart of coastal for more resilience of areas under threat from natural hazards. This call is resilience is the vision of the Draft Mujib Climate Prosperity Plan (Government aligned with the global trend of aiming to enhance the resilience of coastal of Bangladesh 2021), which is the aspiration to shift Bangladesh’s trajectory zones in policies and practices (Masselink and Lazarus 2019). The definition from one of vulnerability to resilience to prosperity. of resilience, let alone the metrics, is ambiguous. Slightly modified from the definition adopted by the International Panel for Climate Change, coastal 1.5. Guidance and Inspiration Towards a More Resilient Coast in resilience is defined herein as “the capacity of the socioeconomic and natural Bangladesh systems in the coastal environment to cope with disturbances, induced by both human and environmental factors, while adapting the essential functions of the Bridging theory and practice, the central question of this report is how systems to an improved state.” Applied to Bangladesh’s coastal zone, resilience greater resilience of Bangladesh’s coast can be achieved in the coming encompasses the coping capacity of the entire coastal system (physical, social, decades. Attempting to answer this question requires a thorough analytical economic) given the exposure to episodic events (for example, cyclones) understanding of the physical characteristics, social structures, and cultural and chronic stressors (for example, SLR, salinity intrusion, erosion), which is norms for this specific context. This requirement is also reflected in the BDP enhanced by adapting the socioeconomic (such as housing, transport, tourism) 2100, which particularly emphasizes the need for a sound knowledge base and natural (such as mangroves, beaches) coastal systems to these shocks and supported by analytical work to inform future investments. stressors. The shocks and stressors are uncertain even now and more so into the future, thus requiring special attention and the development of resilient Practical questions to be answered are: What have we learned regarding coastal strategies that are robust yet flexible. resilience from past interventions in Bangladesh? Are there ways to improve the planning, design, construction, and maintenance of embankment systems? Achieving greater resilience in a human-dominated system like the coast of How can these systems be embedded more attractively into the landscape and Bangladesh is a complex and costly endeavor. As outlined in the beginning benefit the coastal environment and population? Are there alternative ways of this chapter, Bangladesh’s coast has a vast and dense network of polders to deal with coastal erosion? Are there opportunities for better integration and critical infrastructure systems, as well as tens of millions of people living in and use of mangroves in upgrading coastal protection? How can maintenance smaller and larger settlements that earn their livelihoods through a variety of be improved for a more resilient coast? How will trade-offs between the economic activities. Moreover, the wellbeing of coastal inhabitants is inherently uncertain dynamics of the natural system and enabling safe livelihoods for linked to the natural environment and ecosystem services they provide. These coastal communities be balanced? This non-exhaustive list of questions will be factors imply that working towards a more resilient coast will result in trade-offs addressed in this report and sets the scene for recommendations to enhance between the natural environment and the socioeconomic system. However, coastal resilience in the future. Chapter 1: Towards a Resilient Coastal Bangladesh 43 1.6. Notes 2. The administrative delineation of the coastal zone comprises 19 districts, 147 upazilas, and the Exclusive Economic Zone. A distinction is made between upazilas facing the coast or estuary and upazilas located behind (Kamal Uddin and Kaudstaal 2003). The 48 upazilas in 12 districts that are exposed to the sea or lower estuaries are referred to as the exposed coast and the remaining 99 upazilas of the coastal districts are termed the interior coast. The delineation of the coastal zone was approved at the 6th Inter-Ministerial Technical Committee meeting of the Integrated Coastal Zone Management Plan Project on October 25, 2003, chaired by the Secretary of the Ministry of Water Resources. 3. Population numbers are based on the Preliminary Population and Housing Census 2022 (Bangladesh Bureau of Statistics 2022). 4. The Regional Specialized Meteorological Centre, New Delhi, refers to these events as “tropical cyclones,” whereas the Bangladesh Meteorological Department refers to these climate events as “cyclonic storms.” 5. The updated 2009 NAPA for Bangladesh kept the format of the NAPA 2005, and incorporated the findings of studies on impacts, vulnerabilities, and needs assessment adaptations carried out over the last few years. 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Coastal Erosion in Bangladesh.” (Consultant Firms: CDR, Deltares, IWM). Minist ry of Disaster Management and Relief. 2010. National Plan for Disaster Management 2010-2015. Dhaka, Bangladesh. Available at: http://www.dmb. gov.bd/reports/Nataional Plan for Disaster (2010-2015) Final Version.pdf. Chapter 1: Towards a Resilient Coastal Bangladesh 45 OVERVIEW AND TRENDS 2.1. Coastal Landscape and Dynamics 2.2. Coastal Hazards 2.3. Climate and Socioeconomic Change 2.4. Concluding Remarks 2.5. Notes 2.6. References 46 Bangladesh: Enhancing Coastal Resilience in a Changing Climate 2 J. H. Laboyrie CHAPTER 2: OVERVIEW AND TRENDS The coastal zone of Bangladesh is a dynamic and densely populated zone different, with a narrow coastal plain that is only 10 to 50 kilometers wide, hills with numerous opportunities and multiple risks. From the Sundarbans Forest a short distance from the coast, and small river catchment areas draining into in the west (bordering West Bengal, India) to Chattogram in the east (near the sea. Home to approximately 43.82 million people in 2022,6 the coastal India’s Northeastern Region and Myanmar), the coastal zone is between 50 zone is densely populated, with an average of around 930 people per square and 150 kilometers wide, with almost flat topography, interrupted by large tidal kilometer (Bangladesh Bureau of Statistics 2022). Agriculture and aquaculture tributaries that are part of the GBM delta. South of Chattogram, towards the are the main economic activities in the western part of the coastal zone, whereas Naf estuary (bordering Myanmar) near Teknaf, the character of the coast is tourism, trade, and industrial activities dominate the eastern part. Chapter 2: Overview and Trends 47 Although significant development progress has been made, the frequent • Hazards are inherently connected to the coastal zone. The most prominent occurrence of natural hazards, which are expected to become more intense hazard in the coastal zone is cyclone activity, but riverbank and coastal because of climate change, poses a great threat to the development ambitions erosion, salinity intrusion, and land subsidence are also important hazards of the country. Despite the progress made in recent decades, access to in this area. Long-term trends such as SLR as well as the possible change transport networks (roads, rail) and public services such as health, sanitation, in cyclone activity may exacerbate the frequency and magnitude of these and drinking water remains limited in the coastal zone, partly because of hazards. These hazardous events are not deterministic events (such as the natural hazards. Powerful events such as cyclones but also slow-moving tide) but have a certain probability of occurrence now and in the future, threats such as SLR, subsidence, coastal and river erosion, and salinity intrusion both in terms of intensity and of spatial occurrence (for example, the impede development progress, since damage to infrastructure, decreasing landfall location of a cyclone). Therefore, these types of events are generally crop yields, and disruption of public services directly affect the wellbeing of expressed in terms of probabilities, which facilitate a risk-based planning coastal livelihoods. Across a sample of 48 deltas globally, the GBM delta has approach. been identified as the second most at-risk delta in terms of flood risk (Tessler et al. 2015). The combination of fluvial and coastal flood hazards and the large • Exposure refers to the entire inventory of elements in the coastal zone population located in the low-lying coastal zone makes for a high-risk profile that can be impacted by coastal hazards. This includes the population and of the GBM delta, despite the efforts taken to reduce the vulnerability of the their assets (homes and belongings), transport and water infrastructure people and assets exposed. (such as roads, drinking water, sanitation, drainage, and flood protection infrastructure), social infrastructure (healthcare and school facilities), Enhancing resilience of coastal livelihoods requires a thorough understanding agri-and aquaculture areas, and environmental assets, such as mangrove of the existing and future challenges arising from natural hazards, climatic systems and sediment buffers. This inventory is not static, but dynamic in changes, and changing socioeconomic conditions in the coastal zone. As time due to, for example, changes in physical processes, socioeconomic outlined in Chapter 1, coastal resilience refers to an ever-evolving framework. growth, migration, and changes in the economic structure (for example, a It entails the coping capacity of the entire coastal system (physical, social, shift from agriculture to more aquaculture). economic) against natural shocks (such as cyclones) and chronic trends (such as SLR, subsidence, salinity intrusion, erosion), while also maintaining • Vulnerability is the degree to which exposed elements, such as human essential functions (for example housing, transport, tourism) through long- beings, their livelihoods, and infrastructure and natural assets suffer adverse term adaptation. To ultimately understand and define which interventions effects when impacted by a certain hazard. Hazards can cause casualties, improve coastal resilience within the context of the GBM delta, a thorough direct damage to assets, and disruption of services in the coastal zone. understanding of the existing coastal system is imperative. This holistic view The vulnerability of built infrastructure is often related to the engineering of the coastal system needs to be multidimensional, requiring insight into the design standards of these structures (such as the type of housing and the physical, social, and economic functioning of the coastal zone at present as well construction materials used for embankments). Differences in human and as of future trends to support long-term planning. social vulnerability are, however, more complex to quantify as they are associated with the sociodemographic profile, livelihoods strategies, the A common way to better understand coastal resilience against natural hazards strength of social networks, and households’ access to basic services (Nath, is to look at this concept through the lens of risk. Risk is defined as the product van Laerhoven, and Driessen 2019; Rabby, Hossain, and Hasan 2019). of hazard, exposure, and vulnerability. Bangladesh: 48 Enhancing Coastal Resilience in a Changing Climate Thinking in terms of risk is very useful for understanding and enhancing resilience across the Bangladesh coastal zone. First, hazardous events have a probabilistic nature and therefore have a likelihood of occurrence. Cyclones are the best example of this for Bangladesh; different parts of the coast are frequently struck by relatively weak and small tropical storms with minor impacts, but now and then a major cyclone hits the coast with devastating and long-lasting impacts. Thinking in terms of risk forces one to look across all probable events and their impacts on the exposed assets and population. Second, interventions can reduce the hazard, the exposure, or the vulnerability of the assets and population, or a combination of these. Therefore, disentangling the contributions of hazard, exposure, and vulnerability to overall risk helps in better understanding what interventions to target to enhance resilience. For example, flood protection infrastructure reduces the probability of flooding, whereas early warning and evacuation of the population to cyclone shelters reduce the exposure and vulnerability of communities to cyclone winds and floods. Mathijs van Ledden Both interventions affect risk but in a different way, and DRR strategies often consist of a set of complementary interventions to reduce risk (Jongman 2018). This chapter sets the stage for enhancing coastal resilience by providing an overview of the coastal system in terms of the biophysical landscape, the socioeconomic characteristics, and the natural hazards and associated risks. First, the coastal zone is described from a detailed “exposure perspective” to understand the existing physical and ecological system and present the current infrastructure and the communities occupying the coastal zone (Section 2.1). Next, a detailed “hazard perspective” is provided, depicting the types and frequency of hazards that currently affect communities and infrastructure (Section 2.2). This is followed by a detailed description of the relevant ongoing trends in terms of both hazard and exposure that will very likely continue in the decades to come as a result of climate change (such as SLR) and socioeconomic developments (such as population growth and migration) (Section 2.3). Finally, the concluding remarks set the stage for the next chapters of this report (Section 2.4). Chapter 2: S M Mehedi Hasan Overview and Trends 49 2.1. Coastal Landscape and Dynamics Especially over the past 200 years, human interventions in the coastal zone have resulted in changes to the pristine coastal landscape. The most prominent 2.1.1. Landscape and Dynamics change is the transformation of the southwest and southern part of the coast. Previously, the footprint of the Sundarbans mangrove forest in the southwest Bangladesh’s semitropical climate is humid, warm, and primarily driven by was twice as large, covering the coastal zone further north and further east the southwest monsoon and partly by pre-monsoon and post-monsoon up the Meghna estuary. Between roughly 1841–1954, mangrove forests were circulations. Average temperatures are about 26 degrees Celsius and generally cleared and transformed into areas suitable for agriculture (International Water vary between 15 and 34 degrees Celsius throughout the year. The warmest Association 2019). Initially, these areas were only protected from coastal flooding months coincide with the rainy season (March-September), while there is less through seasonal infrastructure provision, but gradually—and especially since rainfall during the winter months (December-February). Nearly 80 percent of the 1960s—more permanent embankments were constructed, resulting in the country’s annual precipitation occurs during the summer monsoon season, the present system of 139 polders. Other relevant large-scale infrastructure bringing large amounts of fresh water to the coastal zone. Severe local storms interventions affecting the coastal landscape have been various closure dams and cyclone events frequently occur during the months of March-May and (such as the Meghna Cross Dams, the Feni Closure) to reclaim land in the October-November, driven by the formation of local depressions due to low- Meghna estuary, and the construction of the two main seaports (Chattogram pressure conditions in the Bay of Bengal. and Mongla) and their access navigation channels with associated dredging requirements. These interventions have caused, and are still causing, changes The coastal landscape of Bangladesh is predominantly shaped by the confluence in physical processes such as the propagation of the tide into the estuary, and of three large rivers: the Ganges-Padma, Brahmaputra-Jamuna, and Meghna sedimentation and erosion patterns along the coast and tidal rivers. (GBM), forming the largest delta in the world and delivering an enormous amount of sediment to the Bay of Bengal. This system discharges approximately Today, this evolving coastal landscape has an ecosystem in which physical and 1 billion tonnes of sediment per year, which accounts for about 10 percent biological processes are at play at different temporal and spatial scales with of the world’s sediment input from rivers to the ocean (Brown and Nicholls many interactions. From an ecosystem perspective, the coastal zone can be 2015). The natural shape of Bangladesh’s coastal zone is controlled by the divided into four different abiotic and biotic environments (Figure 2.2, that can underlying geology and topography of the delta and the dynamic interaction be characterized as follows (Haque and Nicholls 2018 and Rashid 2019): between the influx of water and sediment, coastal processes such as tides and wave action, and episodic events such as cyclones and monsoon rainfall. This The Ganges Tidal Plain West includes the Sundarbans mangrove forest, which interaction between water motion, sediment movements, and the topography creates a natural coastal buffer zone of about 50 to 60 kilometers. Upstream of of the coastal zone is called “morphodynamics” which governs the spatial and the Sundarbans, until about 125 kilometers from the coastline, is a vast system of temporal changes of the coastline and the tidal rivers (Syvitski and Saito 2007). low-lying polders surrounded by a complex river network. This area has a dense It is common to encounter tidal riverbanks eroding and accreting, chars (newly network of drainage channels with low gradients with overall limited freshwater deposited land in the river) being formed and then migrating and disappearing, inflow from the Ganges, mostly through the Gorai River. Still, the interior part and eroding and accreting coastlines. This is an ever-evolving process of nature of the coastal zone is subject to monsoon flood events. The semi-diurnal tide adapting to constantly changing conditions at different temporal and spatial has a tidal range of up to 3 meters at the coast, causing it to propagate far scales and is an inherent characteristic of coasts in general, and the Bangladesh upstream through the large tidal rivers (for example, the Pussur-Sibsa system). coast in particular (see Box 2.1). For instance, near the city of Khulna, the tidal range is still 1.5 meters. There is Bangladesh: 50 Enhancing Coastal Resilience in a Changing Climate Box 2.1: Delta Morphology The three large rivers, the Ganges-Padma, Brahmaputra-Jamuna, Figure 2.1: Shifting of the Main Rivers in Bangladesh over the Last 250 Years and Meghna deliver most of the water and sediment to the GBM delta, which is separated from the Chattogram region by the Feni River. The Ganges-Padma discharges water at an average rate of 11,000 cubic meters per second and about 550 million tonnes of sediment per year (Akter et al. 2016). The Brahmaputra-Jamuna brings an additional 20,000 cubic meters per second of water and approximately 600 million tonnes of sediment towards the GBM delta region. These two rivers join the Meghna River and deliver approximately 1 billion tonnes of sediment through the Lower Meghna River to the coastal zone (Akter et al. 2016). It is considered a tide-dominated delta, meaning the tide, compared to waves and rivers, is the driving force in delta morphology. In some places, the tide can propagate more than 100 kilometers inland (Brown and Nicholls 2015). Although its relative importance may change because of human interventions, it is expected that the tide will become even more dominant in the future (Nienhuis et al. 2020). Over the course of multiple decades, the landforms of the delta have constantly changed, resulting in the shifting and disappearance of existing rivers and the creation of new rivers. This can be seen clearly in Figure 2.1, which illustrates the evolution of rivers over the last 250 years. The modification of the river network has also changed Source: Sarker, Akter, and Rahman 2013. the distribution of water and sediment to different parts of the coast. The result of this is a progradation of the delta towards the east and a large accretion of land in this region (Sarker, Akter, and Rahman 2013). This shifting process is expected to continue in the coming decades, although it may be altered by human modifications upstream (such as dam development). Chapter 2: Overview and Trends 51 Figure 2.2: Delineation of the Four Ecosystem Zones in the Coastal Region Source: Map developed by the World Bank for this report based on data from the BDP 2100 (Baseline Volume 1, pg. 403), Humanitarian Data Exchange, World Bank, ESRI ArcGIS, Maxar, Earthstar Geographics, USDA FSA, USGS, Aerogrid, IGN, IGP, and the GIS User Community. Bangladesh: 52 Enhancing Coastal Resilience in a Changing Climate M Abdullah Abu Diyan M Abdullah Abu Diyan M Abdullah Abu Diyan M Abdullah Abu Diyan Biodiversity in the Sundarbans mangrove forest: (clockwise from top left) the crested serpent eagle, the king cobra, the masked finfoot, and the spotted deer. Chapter 2: Overview and Trends 53 Sayam U. Chowdhury Fishermen and birds coexisting in coastal Bangladesh. Bangladesh: 54 Enhancing Coastal Resilience in a Changing Climate Sayam U. Chowdhury Sayam U. Chowdhury Sayam U. Chowdhury Sayam U. Chowdhury Waterbirds of the Meghna Estuary: (clockwise from top left) the Spoon-billed Sandpiper, Indian Skimmers, the Asian Dowitcher, and Egrets. Chapter 2: Overview and Trends 55 some cyclic erosion and sedimentation occurring along the tidal rivers, while water levels, and waves in this area, especially in the more exposed regions the open coast is predominantly eroding. Cyclones can generate extreme water near the coast. Patches of the Sundarbans mangrove forest (although limited levels and wind speeds in this area. Apart from the open coastline, waves are in number) are located at the coastline, with similar biotic characteristics as generally limited to locally generated wind waves. described above. The Sundarbans mangrove forest (including the part located in India) is a The Meghna Deltaic (Estuary) Plain is a very dynamic and flat estuarine globally unique ecosystem because of its size, the variety of mangrove species, coastal system as a result of the main outflow of the GBM system being in this and the abundance and diversity of its flora and fauna. It covers 6,017 square area. It has several very large polder systems, such as Bhola island, which has a kilometers in Bangladesh (Dasgupta et al. 2021) and has 13 out of the 35 known surface area of more than 300,000 hectares. Some interior parts of the Meghna mangrove types. The biotic diversity comprises 400 species of fish, 53 species Estuary experience elevated water levels during the monsoon season. Storms of reptiles, over 330 species of birds, and 50 species of mammals, and includes and cyclones can further generate high water levels in this area. The tidal range large animals such as spotted deer, crocodiles, and tigers. Fish species include is very high, with values of up to 6 meters near Sandwip island. Large quantities finfish and shellfish, such as shrimp and prawn, lobster, crabs, snails, mussels, of sediment are continuously transported to the shallow coastal shelf, where cuttlefish, and squid. Marine animals like sharks, rays, seahorses, whales, it is reworked by the interaction of tides and waves. The Meghna Plain has an dolphins, turtles, and sea snakes also live in this region. The mudflats exposed outbuilding coastline, indicating that new land is being formed at a rate faster during low tide are rich in microorganisms that are ideal feeding grounds for than the erosion of existing land in this area. Therefore, the planform of the migratory birds. The Sundarbans are home to 17 globally threatened species, region is rapidly changing, with certain areas advancing more than 100 meters including the Pallas’s fish eagle (Haliaeetus leucoryphus), the Gyps bengalensis or more per year. vulture, and the Aquila clanga spotted eagle (Sarkar 2017). The Bangladesh portion of the Sundarbans was declared a Ramsar site in 1992 under the The Meghna Estuary is an extraordinarily rich ecosystem due to the mix of tidal Convention on Wetlands and is therefore recognized as a wetland site of and river waters, the continuous supply of sediments and nutrients, and remote international importance. In addition, the GoB has created three wildlife and intertidal areas. The islands in the estuary mouth are a strategic location in the three dolphin sanctuaries in the north of the Sundarbans along the Pussur, East Asian-Australasian Flyway, housing waders and other waterbirds during the Shela, and Bhola Rivers. winter months. More than 100,000 birds visit this area, among which are critically endangered birds like the Spoon-billed Sandpiper, Nordmann’s Greenshank, The Ganges Tidal Plain East has a flat topography with most areas located just the Asian Dowitcher, and the Great Knot. As per a shorebird and waterbird above MSL. There is an extensive system of polders from the open coastline survey conducted in the Meghna Estuary in 2016, Spoon-billed Sandpipers were to about 60 kilometers inland. The area is intersected by several rivers that counted, along with nine globally near threatened and threatened species of receive fresh water from the Lower Meghna River and from the Padma River shorebirds—Spotted Greenshanks, Great Knots, Eurasian Curlews, Black-tailed via the Arial Khan River. The tidal range along the coast is high (3.5 meters) Godwits, Bar-tailed Godwits, Red Knots, Curlew Sandpipers, Little/Red-necked but decreases further inland. The tidal rivers show cyclic behavior of erosion Stints, and Asian Dowitchers (S. U. Chowdhury et al. 2018). These birds feed and sedimentation, with morphological hotspots often located in the laterally themselves with benthic organisms, mollusks, crustaceans, and marine worms. migrating river bends. However, the magnitude is generally limited to a few The intertidal areas in the estuary also serve as the nursery and feeding ground meters per year. Most of the coastal area is subject to structural erosion at for many fish species, such as the Hilsa and Panga. a similar rate. Cyclones are the predominant cause of extreme wind speeds, Bangladesh: 56 Enhancing Coastal Resilience in a Changing Climate The Chattogram Coastal Plain is a relatively narrow and flat coastal area with (roads, waterways, ports), provide essential health and social services (health a steep gradient in the coastal hinterland. Between Chattogram and Cox’s centers, schools), and allow agriculture, aquaculture, and other economic Bazar, there is a narrow strip of small polders along with a few polders further activities to take place in the polder systems (water management systems). south of this point. The tide ranges from 6 meters in the far north to about The four main infrastructure systems—water management infrastructure, road 3 meters near Teknaf (the southernmost upazila in Bangladesh). The coastal and rail infrastructure, inland waterway transport infrastructure, and social strip is directly exposed to winds and storm surges originating from cyclones infrastructure—are briefly summarized below. and tropical depressions. Additionally, the steep gradient, and the tendency of hills to generate intense rainfall events, produce rapid runoff events. The rivers Water Management Infrastructure and other drainage channels across the flat coastal plain cannot safely convey these episodic downpours, leading to flash floods in the region. Sediment In the early 1960s, the first set of 108 coastal polders was constructed within is delivered to the coast by small rivers originating from the hilly hinterland. the Coastal Embankment Project (CEP), reshaping the coastal zone and forming The predominant wave direction from the south generates a large longshore the infrastructure backbone of the coastal districts. Polders prevent saline water transport of sediments towards the north, redistributing river sediments along from entering agricultural fields, thereby boosting agricultural productivity and the coast and causing time-varying erosion and deposition. providing food security for the millions of people living in the polder areas. On top of that, they protect against frequent tidal flooding, thereby preventing This region has a large variety of ecosystems, with some small pockets of damage to people and crops and stimulating economic development for the natural mangrove forests, small estuaries, sand dunes, and beaches. One local polder communities (M. Zaman 1983). mangrove area of ecological importance is located in the low-lying (saline) swamp at the mouth of the Matamuhuri River delta (near Cox’s Bazar). This Currently, there are 139 polders across the coastal zone, covering an area of 1.2 area, known as Chakoria Sundarbans, provides a habitat for a variety of marine million hectares (25 percent of the coastal zone). While the average size of a and terrestrial organisms (Prince et al. 2018). Another area of ecological interest polder is about 9,000 hectares, they vary widely, with roughly 80 percent of the is the Teknaf Peninsula, which has one of the longest sandy beach ecosystems polders having a size of between 2,000 and 20,000 hectares (see Figure 2.3). in the world (80 kilometers) (M. S. N. Chowdhury et al. 2011). This area has a Although originally the polders were designed to protect against tidal flooding mixture of mangroves, mudflats, lagoons, beaches, and sand dunes. It provides only, recently, as part of the Coastal Embankment Improvement Project Phase breeding grounds for two globally threatened species of marine turtles and is I (CEIP-I), the first set of polders are being rehabilitated to protect against located along multiple international bird migration flyways. To protect the rich storm surges in addition to tidal flooding. Moreover, these upgraded designs biodiversity along the coast, the region has three protected areas: Cox’s Bazaar being implemented by CEIP-I have taken projections of climate change into – Teknaf Wildlife Sanctuary, Himchhari National Park, and Inani National Park. consideration. 2.1.2. Infrastructure Systems The polders are characterized by two main water infrastructure elements: coastal embankments surrounding the polder and an extensive drainage system inside The coastal zone houses various infrastructure systems that provide essential the polder. In total, there are about 6,000 kilometers of embankments in the services to coastal communities, as well as being of strategic importance to coastal zone (Dasgupta et al. 2011), most of which are earthen embankments the economy of Bangladesh. They ensure protection against flooding (polder with a grass cover and a road on top. The elevation of these embankments embankment systems), enable the transportation of people and goods varies but is typically 2 to 4 meters above ground level. Where necessary, there Chapter 2: Overview and Trends 57 Figure 2.3: Location of Embankments that Delineate Polder Boundaries Source: Map developed by the World Bank for this report based on data from the BWDB, World Bank, ESRI ArcGIS, Maxar, Earthstar Geographics, USDA FSA, USGS, Aerogrid, IGN, IGP, and the GIS User Community. Bangladesh: 58 Enhancing Coastal Resilience in a Changing Climate J. H. Laboyrie Md. Towshikur Rahman Water management infrastructure (a drainage sluice) under construction. Water management infrastructure (a drainage sluice) for Polder 35/3). is slope protection on the outer side of the embankment to protect against fresh water and store it for later use. As such, sluices constructed initially only cyclone-induced waves and to ensure stability at places where river and coastal for drainage purposes started being used for drainage and flushing. However, erosion is taking place. Given the lack of rock in Bangladesh, slope and bank the use of a one-way drainage sluice to allow reverse flows has damaged these protections are typically designed and made using cement concrete blocks. structures. The CEIP-I is now constructing both drainage and flushing structures as two-way regulators to drain excess water from the polder to the river but The polders are crisscrossed by a gravity-based drainage network that consists also allow the river water to enter into the polder area.7 It is estimated that the of small canals (khals), and large drainage and flushing sluices to regulate the 139 polders together have approximately 8,000 kilometers of canals, more than water level and drain excess water out of the polder. The khals are typically a 1,300 drainage structures, and more than 1,700 regulators.8 few meters wide and relatively shallow and connect the drainage structures with the interior of the polder. When originally built, drainage structures within Road and Rail Infrastructure the embankment system connected the internal drainage system with the adjacent river network to drain excess water from the polder area. As time The coastal zone has a dense road network connecting the rural communities went on, agricultural practices developed among farmers to cultivate winter to the large urban centers (Chattogram, Khulna, Barisal). Moreover, the primary Boro rice inside the polder. For this winter agriculture, farmers started to take roads form the main hinterland transport network that connects the three Chapter 2: Overview and Trends 59 J. H. Laboyrie Coastal embankment, slope protective works, slope plantation, and turfing in Polder 32. Bangladesh: 60 Enhancing Coastal Resilience in a Changing Climate Ismail Ferdous A khal (small canal) in a coastal polder. Chapter 2: Overview and Trends 61 coastal seaports (Chattogram, Mongla, and Payra) with the Rail networks are scarce in the coastal zone. The western railroad ends in Khulna and connects the city rest of Bangladesh. In Bangladesh, there are six categories with India and northwestern Bangladesh. The eastern railroad connects the city of Chattogram with of roads: national highways, regional highways, zila roads, northern Bangladesh, including Dhaka. This railroad is particularly important for freight movement upazila roads, union roads, and village roads A and B. The between the port of Chattogram and Dhaka, which is more cost and time efficient than if done by arterial network of national highways, regional highways, truck or inland water transport. On a yearly basis, almost 90,000 20-foot equivalent units of containers and zila roads are under the jurisdiction of the Roads and travel between the port of Chattogram and the Dhaka Inland Container Depot (JOC 2019). Highways Department. They comprise a length of 13,700 kilometers in the coastal zone, most of which is paved. Table 2.1: LGED Coastal District Road Network The Local Government Engineering Department (LGED) is Coastal District Earthen Road Paved Road Total Earthen Paved Road responsible for the remaining road categories, of which (km) (km) (km) Road (%) (%) approximately 65 percent of the roads are unpaved. LGED’s earthen unpaved road network is extensive in the Khulna 3,224 3,211 6,435 50% 50% coastal zone, covering a total of about 83,556 kilometers Bagerhat 4,197 2,548 6,745 62% 38% (Table 2.1), and includes the roads that are located on Bhola 3,039 2,518 5,557 55% 45% top of the many polder embankments. Barisal 7,745 2,933 10,678 73% 27% Shatkhira 4,075 2,422 6,497 63% 37% The main road access to the coastal zone is through the Patuakhali 9,812 2,525 12,337 80% 20% national highway system. Towards the west, national highway N8 connects Dhaka with Jashore and further Noakhali 6,599 3,696 10,295 64% 36% to the Indian-Bangladesh border (see Figure 2.4). The Chattogram 9,290 4,782 14,072 66% 34% important economic locations, including Mongla port and Cox’s Bazar 2,887 1,543 4,430 65% 35% Khulna (via the N7), Gopalganj (on the N805), and Barisal Jashore 5,979 3,260 9,239 65% 35% (on the N8), are also connected to this national highway Narail 1,997 994 2,991 67% 33% system. Travel times between the western coastal zone Gopalganj 2,511 2,322 4,833 52% 48% and the northern and eastern areas of the country will be significantly reduced when the Padma Multipurpose Pirojpur 2,889 1,877 4,766 61% 39% Bridge project is completed in 2022, enabling the Jhalokathi 3,047 1,114 4,161 73% 27% transport of passengers and freight across the Padma Barguna 4,872 1,470 6,342 77% 23% River (the main distributary of the Ganges). The main Shariatpur 2,014 1,479 3,493 58% 42% highway towards the eastern part of the coastal zone is Lakshmipur 3,850 1,948 5,798 66% 34% national highway N1, which connects Feni, the city and Chandpur 3,642 2,098 5,740 63% 37% port of Chattogram, and Cox’s Bazar, and runs towards Teknaf Upazila and the border with Myanmar. Feni 1,887 2,112 3,999 47% 53% Total 83,556 44,852 128,408 65% 35% Source: LGED Road and Market Database as of June 2021 (https://oldweb.lged.gov.bd/ViewRoad2.aspx). Bangladesh: 62 Enhancing Coastal Resilience in a Changing Climate Figure 2.4: Overview of the Road Network in the Coastal Zone Source: LGED Road and Market Database as of June 2021 (https://oldweb.lged.gov.bd/ViewRoad2.aspx). Note: Only highways, zila roads, and upazila roads are shown. Chapter 2: Overview and Trends 63 Inland Waterway Transport Infrastructure Social Infrastructure Water transport is a major mode of transport for the movement of goods and Educational and Healthcare Facilities people in Bangladesh. The country has about 6,000 kilometers of waterways that are navigable for mechanized vessels, of which about 3,800 kilometers are Educational and healthcare facilities are the main types of social infrastructure accessible year-round (World Bank 2007). This navigable river system falls under in the coastal zone. In total, the coastal zone has about 21,500 educational the jurisdiction of the Bangladesh Inland Water Transport Authority and can be facilities, ranging from kindergartens to universities (HDX, n.d.).9 There are more categorized into four classes with different characteristics in terms of minimum school facilities in the interior coastal zone (13,250) than the exposed coastal draught (Classes I – IV). The Bangladesh Inland Water Transport Authority, zone (8,250), reflecting the difference in population density. In Bangladesh, together with the Bangladesh Inland Water Transport Cooperation, manages a many of these primary educational facilities are constructed by the LGED. In total of 2,000 passenger launches and 22 inland ports, which include about 800 recent investment programs (for example, the Multipurpose Disaster Shelter launch ghats and terminals, throughout the country (W. Zaman 2020). Apart Project (MDSP), school facilities have been integrated into the construction from mechanized vessels, traditional country boats have been plying inland of cyclone shelters, also known as multipurpose disaster shelters (see the and coastal waters for hundreds of years. Several hundred thousand of these following discussion). country boats still operate in Bangladesh and play a key role as a rural mode of transport. There are a total of 719 healthcare facilities in the coastal zone — 483 located in the interior coastal zone and 23610 located in the exposed coastal zone. The coastal zone has a dense network of navigable waterways, especially in its Information regarding the size and service level of these facilities was not western portion. There is a Class I navigable waterway with a maximum draft of available at the time of reporting. about 4 meters between Dhaka and Chattogram, and between Dhaka, Barisal, and Khulna via the port of Mongla. The two largest inland ports in the coastal Multipurpose Disaster Shelters zone are the ports of Chattogram and Mongla. Oceangoing vessels can enter these ports with a maximum draft of 8.5 and 6 meters, respectively, from the Bay Multipurpose disaster shelters are a specific type of infrastructure and are of Bengal. To accommodate the expected growth in trade in the future, a number found throughout the entire coastal zone. At present, approximately 5,000 of new port projects are being prepared or are already under development. multipurpose disaster shelters are strategically located across the coastal zone, These projects include terminal expansions for the ports of Chattogram and with a higher density in the most at-risk areas. They have been built to provide Mongla, the construction of a new deep-sea port near Cox’s Bazaar (Matarbari a safe haven for millions of people during cyclone events. One of the first major Port), and further development phases of the newly constructed Payra Seaport projects to construct cyclone shelters was the World Bank supported Cyclone (Port Strategy 2020). These port developments should facilitate the expected Protection and Coastal Area Rehabilitation Project, which began in 1971 after doubling of container traffic by 2040 (Asian Development Bank 2015), and devastating Cyclone Bhola hit the country in November 1970. Since then, there better connect the coastal zone with international land and sea corridors (such have been more multipurpose disaster shelter projects. Following Cyclone Sidr as the Belt and Road Initiative). (2007), new programs, such as the Emergency 2007 Cyclone Recovery and Restoration Project (ECRRP) and the MDSP have been initiated to rehabilitate and build new shelters. The MDSP, which was approved in 2014, is expected to result in the construction of 550 new shelters, the rehabilitation of 450 shelters, Bangladesh: 64 Enhancing Coastal Resilience in a Changing Climate and the construction of 550 kilometers of rural roads to improve accessibility. It Box 2.2: Accessibility of Cyclone Shelters is estimated that a total of approximately 7,000 multipurpose disaster shelters will be needed by 2025 to improve disaster resilience across the coastal zone The accessibility of cyclone shelters is an important factor that determines the (World Bank 2020). success of large-scale evacuations (Mallick 2014). As a first order indicator, the walking distance between households and the closest shelter can be used Generally, disaster shelters are multistory buildings (2 or 3 floors) with about to measure accessibility. In Figure 2.5, the distribution of the population with 300 square meters of floor space made of concrete with an open space at respect to their walking distance to the closest shelter is depicted for 16 of the ground level (Miyaji, Okazaki, and Ochiai 2020). The capacity of existing shelters 19 coastal districts (grey lines) that have shelters and the population weighted typically ranges between 600 to 1,500 people, with an average of 1,000 people average across these districts (black line). The data is based on synthetic (LGED 2010). The density of shelters and their accessibility differ by location. household data of the districts (Rubinyi, Hall, and Gussenbauer 2021), including An analysis of the locations of households and shelters (see Box 2.2) found the geographical locations of households, and of cyclone shelters. that an estimated 50 percent of the coastal population have a shelter within a 2-kilometer distance from their house, although this number ranges from Across all coastal districts, 50 percent of the population live within a 2-kilometer 0.6 kilometers in Cox’s Bazar and Bhola to more than 4 kilometers in Khulna, radius of a cyclone shelter, while 90 percent live within an 8.7-kilometer radius. Noakhali, and Barisal. Figure 2.5: Walking Distance between Households and Cyclone Shelters These cyclone shelters often serve multiple purposes, functioning as schools, community centers, and medical facilities throughout the year, and as disaster shelters during cyclones. For instance, of the 4,000 shelters included in the LGED’s shelter database (LGED 2010), approximately 80 percent function as educational facilities, while only 7 percent have no multipurpose use. The shelter programs instituted after Cyclone Sidr included innovations such as inclusive design elements of universal accessibility, consideration of gender- sensitive requirements (for example, separate sanitary facilities and rooms for nursing mothers), water supply, rainwater harvesting, and solar panels (Faruk, Ashraf, and Ferdaus 2018). Ramps were also included for livestock accessibility as were designated spaces for the animals. In addition, more recent shelter designs use materials that can withstand very high wind speeds. 2.1.3. Population, Livelihoods, and Wellbeing Coastal communities are spread across the entire coastal zone and engage in different economic activities. Four aspects of these communities are discussed Source: Analytics performed by the World Bank for this report. in the following sections—population, housing and public services, economic Note: The light grey lines depict the distribution per district, and the thick black line is activities, and poverty and wellbeing. the distribution for the coastal zone as a whole. Swarna Kazi A multipurpose disaster shelter and primary school in coastal Bangladesh. Bangladesh: 66 Enhancing Coastal Resilience in a Changing Climate Ismail Ferdous A multipurpose disaster shelter functioning as a primary school. Chapter 2: Overview and Trends 67 Population There are 10 upazilas with a high population density (greater than 10,000 people per square kilometer); five upazilas west of the Meghna Estuary—Jashore, The coastal zone has 19 districts with approximately 43.82 million people of Khulna, Khalispur, Sonadanga, and Palong—which are all located in the interior which around 27.04 million live in the interior coastal zone, while the remaining coast, and five upazilas east of the Meghna Estuary—Chattogram port, Double 16.78 million live in the exposed coastal zone (see Figure 2.6). The average Mooring, Pahartali, Panchlaish, and Chandgaon—which are all located in the density in the coastal zone is some 930 persons per square kilometer (Bangladesh exposed coast (all within Chattogram district). Approximately 77 percent of the Bureau of Statistics 2022).11 The population density generally increases away coastal population reside in rural areas, with Satkhira district considered the from the coast: the interior coast has roughly a 50 percent higher population most rural, and Khulna and Chattogram the most urban districts. density than the exposed coast (1,180 versus 770 people per square kilometer) (see Figure 2.7). Despite this coast-inland divide, the population is quite evenly The demographics of the coastal zone are similar to Bangladesh as a whole, spread throughout the coastal zone. About 70 percent of the upazilas in the on most levels. The country has a relatively young population, with about 40 coastal zone have a population density of between 500 and 1,500 people per percent under 20 years old. The average number of people per household in square kilometer. the coastal zone is about five, although this is slightly declining, which mirrors Figure 2.6: Coastal Upazilas of Bangladesh by Exposed Coast and Interior Coast Figure 2.7: Population Distribution of the Coastal Upazilas of Bangladesh, 2021 Source: Map developed by the World Bank for this report based on data from the Source: Map developed by the World Bank for this report based on data from the Humanitarian Data Exchange, the Program Development Office for Integrated Coastal Bangladesh Bureau of Statistics, the Humanitarian Data Exchange, and the World Bank, Zone Management Plan, and the World Bank. projected for 2021. Bangladesh: 68 Enhancing Coastal Resilience in a Changing Climate the national average (Szabo, Ahmad, and Adger 2018). Although more men urban and rural areas in Bangladesh. Still, disparities between income groups than women are born, the sex ratio across the entire population is 0.95 (i.e. 95 are prevalent. People living in poor households are 10 times more likely to men for every 100 women). The fertility rate has decreased significantly, from use unimproved sanitation than households in the richest quantile (Bangladesh approximately seven in the 1960s to approximately two in 2020. Life expectancy Bureau of Statistics and UNICEF Bangladesh 2014). Access to clean drinking has increased significantly, from about 40 years in the early 1950s to over 70 water is much higher (85 percent) and predominantly achieved by piped water years in 2018, with women living longer than men (74 versus 71) (Bangladesh and tube wells. The number of households utilizing piped water has increased Bureau of Statistics 2019). However, some districts have lower life expectancies in the coastal zone, yet the main source of water remains tube wells (Argos et al. than the average, for example in Barisal, it is only 70 years for women (Szabo, 2010; Hossain, Dearing, et al. 2016). Arsenic is a major threat to the water supply Ahmad, and Adger 2018). Infant mortality in Bangladesh dropped to about 65 in both rural and urban areas. Arsenic in water has adverse health impacts, percent over the period between 1989 and 2014 (Khan and Awan 2017). Infant and an estimated 50 million people in Bangladesh are currently exposed to mortality tends to be lower than the national average in the western coastal arsenic through drinking water (Ahmad, Khan, and Haque 2018). In the coastal zone, while the eastern districts are lagging behind (Szabo, Ahmad, and Adger zone, this issue is particularly relevant for the Khulna and Chattogram divisions. 2018). There is similar access to electricity as there is to sanitation, with 53 percent of the coastal population having access to an electricity supply, although with Housing and Public Services large disparities between upazilas (from a low of 7.1 percent to a high of 99.2 percent) (Bangladesh Bureau of Statistics 2011). Residential housing quality varies widely throughout the coastal zone. The types of housing in the coastal zone range from permanent to temporary and The access to and quality of education and healthcare also provide insight can be classified into four categories based on the quality of the roof and walls: into the living conditions of coastal communities. As of 2019, the literacy rate pucca (improved housing made of brick and concrete), semi-pucca (improved in Bangladesh was about 75 percent (UNESCO Institute for Statistics, n. d.). housing with the foundation made of brick and concrete, and the walls and A literacy survey from 2008 found that the literacy rate in rural areas is 12 roof made of corrugated iron sheets), kutcha (unimproved housing made of percent lower than that of urban areas, whereas differences across the country earthen plinths with bamboo and walls made of organic material), and jhupri and between men and women are small (Bangladesh Bureau of Statistics (unimproved temporary housing made of straw or bamboo). Typically, the 2008). Access to primary education has improved significantly in the coastal housing quality in urban centers is better compared to more rural areas. On zone, from 23 to 47 percent between 1993 and 2010, including a closing of average, about 20 percent of the coastal population live in improved housing, the gender gap in education access (Hossain, Johnson, et al. 2016). Access to although there is a large variation between districts (for example, 7 percent live necessary healthcare remains challenging for people living in the coastal areas, in improved housing in Barguna compared to 42 percent in Khulna) (Bangladesh particularly the marginalized and disabled (Huda et al. 2020). These areas suffer Bureau of Statistics 2011). The number of houses of better quality has been from a lack of appropriate health facilities and skilled healthcare providers. Still, increasing over the last several years and it is expected that by 2050, the vast between 1993 and 2010, the percentage of births attended by skilled personnel majority of households will live in improved housing (Dasgupta et al. 2014). increased from about 10 to 40 percent in the coastal zone (Hossain, Johnson, et al. 2016). Sanitation and drinking water are two essential public services for coastal communities. The coverage of sanitation was about 55 to 57 percent in 2010 (Joint Monitoring Programme 2012) and does not differ very much between Chapter 2: Overview and Trends 69 Economic Activities The main crops in the coastal zone are cereals, pulses, vegetables, fruits, and cash crops like jute and sugarcane. Rice is the predominant crop, and includes A majority of the coastal population is highly dependent on agriculture as a variants like Aus, Boro, and Aman rice. The traditional cropping pattern is to source of income and for food security. This is especially true for the polder plant Boro rice during the Rabi season (mid-November to mid-March), allow areas, which are dominant in the Ganges Tidal Plain West and East and the the land to lie fallow during the Karif-1 season (mid-March to mid-July), and use Meghna Estuary. In 2013, 1.2 million hectares of land were being utilized for transplanted Aman rice during the Kharif-2 season (mid-July to mid-November) agricultural purposes within the embankment system, which represents almost (Lázár et al. 2015). In total, the agricultural sector employs 4.6 million people, 15 percent of Bangladesh’s total arable land (World Bank 2013). which is 46 percent of total coastal employment. This number is even higher in some upazilas (up to 81 percent), as can be seen in Figure 2.8. Figure 2.8: Primary Employment in the Agriculture (left) and Services (right) Sectors at the Upazila Level Source: Bangladesh Bureau of Statistics 2011. Bangladesh: 70 Enhancing Coastal Resilience in a Changing Climate The ship-breaking and recycling industry is another important economic Aquaculture has grown rapidly in the past few decades in the polders around activity, mainly concentrated in Chattogram. This activity converts end-of-life Cox’s Bazar and Chattogram in the southeast, and near Jashore and Khulna in ships into steel and other recyclable parts. It provides direct employment to particular in the southwest (see Figure 2.9). Bangladesh exports about 40,000 about 30,000 people and contributes to the creation of indirect jobs (such as tons of shrimp, which is equal to approximately 2 percent of the global shrimp downstream recycling and services). Employment in the service sector is high market (Shamsuzzaman et al. 2020). Shrimp farming is predominantly carried near Chattogram, Cox’s Bazar, and Barisal (Figure 2.8). out in aquaculture ponds in areas where the soil and water have become too saline for agricultural production. Both brackish water shrimp (bagda) Fishing is an increasingly important economic activity in the coastal zone, and freshwater shrimp (galda) are produced in small-sized farms that cover generating income and employment for around 2.5 million people. The more than 200,000 hectares (Mukhopadhyay et al. 2018). Shrimp farming has amount of marine captured fish was approximately 650,000 tons in 2018 large monetary benefits compared to agriculture, explaining its widespread (Shamsuzzaman et al. 2020), of which Hilsa shad is the predominant species. adoption. Households engaged in shrimp farming earn three to four times Figure 2.9: Rapid Expansion of the Aquaculture Area in the Western Coastal Zone between 1989 and 2010 Source: Mukhopadhyay et al. 2018. Chapter 2: Overview and Trends 71 more compared to households engaged in agriculture (Hossain, Johnson, et al. Figure 2.10: Locations of Approved and Planned Special Economic Zones in 2016). However, shrimp farming is associated with negative consequences, such Coastal Bangladesh as livelihood displacement, income loss, environmental impacts (such as soil toxicity) and food insecurity (Mukhopadhyay et al. 2018; Nath, van Laerhoven, and Driessen 2019). Hence, despite the economic benefits of shrimp farming, studies indicate that it may not be a sustainable solution to counteract poverty and could even increase local poverty rates (Amoako Johnson et al. 2016). Other important activities in the coastal zone are industrial and commercial activities, services, forestry, salt production, ship-breaking and recycling, and tourism (General Economics Division, Bangladesh Planning Commission 2018). The three main city centers of Chattogram, Khulna, and Barisal are hubs for commercial and industrial activities. In addition, several special economic zones (SEZs) have been established in Bangladesh, which are intended to boost foreign direct investment, employment, and exports, all contributing to economic growth (Figure 2.10). As of 2019, there were a total of 88 SEZs. Most of the large SEZs in the coastal zone are near the airports and seaports, thereby benefiting from efficient transport networks and logistics services. By 2025, the Source: Map developed by the World Bank for this report based on data from the GoB intends to establish another 12 SEZs throughout the country, including in Humanitarian Data Exchange, BEZA 2020, and the World Bank. the coastal zone. Note: Only the planned SEZs that could be geolocated are included in the map and therefore not all planned SEZs are depicted. Salt production has a long tradition in Bangladesh and is concentrated in the southeast near Chattogram and Cox’s Bazar. This activity is economically Poverty and Wellbeing important for about 1 to 1.5 million people in the coastal zone. Wellbeing covers multiple dimensions of the quality of human development, Tourism, although still in its infancy in Bangladesh, is a major contributor to reflected, among others, by the differences in livelihoods opportunities and the service sector. In 2018, the tourism sector comprised 4.4 percent of total living standards. Poverty and wellbeing are intrinsically linked (ODI 2012). The GDP. The country has seen a rise in international tourists, with 1.02 million coastal belt of Bangladesh is among the poorest regions of the country, with a visiting Bangladesh in 2017—23 percent higher than 2016 (Deb and Nafi 2020). GDP per capita (in 15 out of the 19 coastal districts) that is below the national However, domestic tourists far outweigh international tourists, with about 10 average, notwithstanding that Chattogram and Khulna are relatively advanced million people travelling domestically within Bangladesh every year (Deb and among the coastal districts of Bangladesh. However, defining and measuring Nafi 2020). Cox’s Bazar is a well-developed tourist destination, with natural and poverty is often controversial, as measuring poverty in terms of income (as GDP cultural attractions. The Sundarbans, Kuakata Beach, and St. Martin’s Island also per capita) alone does not capture the multidimensional nature of poverty. attract both local and foreign visitors. Bangladesh: 72 Enhancing Coastal Resilience in a Changing Climate Mahfuzul Hasan Bhuiyan Ismail Ferdous Mahfuzul Hasan Bhuiyan Mahfuzul Hasan Bhuiyan Chapter 2: Overview and Trends 73 Mahfuzul Hasan Bhuiyan Agricultural activity in a coastal polder. Bangladesh: 74 Enhancing Coastal Resilience in a Changing Climate Mahfuzul Hasan Bhuiyan A fisherman in coastal Bangladesh. Chapter 2: Overview and Trends 75 Bangladesh uses a “Cost of Basic Needs” approach to measuring poverty, which evidence is mixed. For instance, one study showed that households exposed calculates the cost of a bundle of basic consumption needs (food and non- to crop failures and flood events are more likely to migrate (Gray and Mueller food allowances) compared to income. Using this approach, the poverty rate in 2012), while others report that certain factors prevent people from migrating, Bangladesh was equal to 24.3 percent in 2016. Poverty is more prevalent in the with migration seen as a last resort (Penning-Rowsell, Sultana, and Thompson coastal region, with almost 60 percent of all coastal upazilas having an above 2013). For instance, after Cyclone Aila in 2009, a study (Saha 2017) found that average poverty incidence and the more urban areas, such as Chattogram, households were reluctant to migrate but felt they had no other option than to having considerably lower poverty rates (Bangladesh Bureau of Statistics 2016). move to the city of Khulna. Multidimensional poverty indices combine both monetary indicators and non- 2.2. Coastal Hazards monetary indicators (for example, school attendance, nutrition, electricity, cooking fuel) (Alkire and Foster 2011). For instance, malnutrition in children is The coastal zone of Bangladesh is prone to climate-related coastal hazards, prevalent in Bangladesh; in 2012, 33.8 percent of children were underweight including episodic events and long-term stressors. The most pronounced and 7.9 percent were severely underweight. The underweight rates in the coastal hazard is the occurrence of cyclone events. Slow-moving chronic stressors are zone are somewhat lower than the national average. The numbers indicate also prevalent, such as coastal and river erosion, waterlogging, subsidence, and that 47 percent of coastal upazilas have an underweight percentage that is salinity intrusion. These chronic stressors can result in loss of land, infrastructure higher than the national average and 53 percent have a lower one. Moreover, failures, difficulties in operating the polder drainage systems, and reduced 43 percent of the coastal upazilas have a severe underweight percentage that agricultural productivity. A synopsis of these coastal hazards is provided below. is higher than the national average, and 57 percent have a lower one (World Food Programme 2012). Indicators of education and living standards have 2.2.1. Cyclones been discussed in previous sections. The coastal zone of Bangladesh is prone to tropical cyclone events, originating Migration from low atmospheric pressure fields over the Bay of Bengal. Cyclones generally occur in early summer (April-May) and the late part of the rainy season (October- Migration is a complex phenomenon, driven by a diverse set of push (i.e. November) and usually follow a northeasterly track. They are accompanied by low wages, environmental degradation, natural disasters) and pull (i.e. more strong winds, storm surges, waves, and rainfall. Although cyclone activity in jobs, higher wages) factors. Migration can be either temporary or permanent. the Northern Indian Ocean alone accounts for only 5 percent of global cyclone Temporary migration is common in the coastal zone and involves seeking activity, 65 percent of all reported loss of life occurred in this area (Woodruff, temporary opportunities (of about six months) in terms of better earnings, Irish, and Camargo 2013). Indeed, numerous devastating cyclone events have schooling, and urban amenities (Bernzen, Jenkins, and Braun 2019). In terms occurred in the past, following different tracks and intensities (see Figure 2.11). of permanent migration, two-thirds of permanent migration is from rural to On average, Bangladesh is hit by one cyclone per year (winds > 63 km per urban. In 2011, almost 10 percent of the total population of Bangladesh were hour). Cyclones affecting the region with strong sustained winds (> 118 km per lifetime migrants (Bangladesh Bureau of Statistics 2011). The main driver for hour) have an average frequency of once every three years (Islam and Peterson migration out of the coastal zone is a combination of environmental stressors, 2009; Dasgupta et al. 2014). The spatial variation of cyclone landfall locations economic vulnerability, and the prospect of remittance income (Szabo, Ahmad, in Bangladesh is limited. Analysis of historical records (between A.D. 1000 and and Adger 2018). Exposure to natural hazards can spur migration, although the 2009) shows that the major urban centers of the coastal zone (Khulna, Barisal, Bangladesh: 76 Enhancing Coastal Resilience in a Changing Climate Asif Aminur Rashid Chapter 2: Overview and Trends 77 Figure 2.11: Tracks of Major Cyclones along Coastal Bangladesh (1685-2020) Source: Map developed by the World Bank for this report based on data from the Humanitarian Data Exchange, the United Nations Environment Programme, the Bangladesh Meteorological Department, and the World Bank. Bangladesh: 78 Enhancing Coastal Resilience in a Changing Climate Chattogram) have each been struck by a comparable number of 40 to 50 cyclones range from 3 to 5 meters but reached more than 10 meters during tropical cyclones (Alam, Momtaz, and Calgaro 2012). However, other analysis Cyclone Bhola in 1970, which was the most devastating event in recent history has found that the frequency of occurrence of landfalling cyclones is slightly (Dasgupta et al. 2010). Storm surges can travel far inland along the tidal river higher in the west of the coastal zone (0.25 cyclones per year) than the east branches and thus cause high water levels around polder embankments, even (0.16 cyclones per year) (Islam and Peterson 2009). a long distance from the coast. For instance, surge levels in the western tidal channels can be as high as 4 to 6 meters for extreme surges (for a 100-year The cyclone wind speeds in the coastal zone vary depending on inland event) (see Chapter 3). decay, differences in topography, and the presence of vegetation, such as the Sundarbans mangrove forest. Typically, there is an abrupt change in Cyclone winds also generate waves, which mainly affect exposed locations wind speed when a cyclone crosses the coastline because of the cutoff of along the coast. These waves are generated by strong winds in the deep ocean the moisture supply that fuels the cyclone (Kaplan and DeMaria 1995; Li and and propagate towards the shoreline. The shallow bathymetry near the coast Chakraborty 2020). As it moves inland, maximum sustained winds decrease results in the partial breaking of these waves, which limits the wave height. The further due to the friction of the land surface. This decay depends on a range of coastal areas that are most exposed to these waves are the polder areas along factors, such as the forward speed of the cyclone, the type of vegetation, and the coastline west of the Meghna Estuary, the polders in the mouth of the the topography. The highest wind speeds along the coastal zone are found in Meghna Estuary, and the Chattogram-Teknaf coastal strip. Typical nearshore the Ganges Tidal Plain, the outer islands in the Meghna Estuary (Sandwip), and wave heights during cyclones in these areas are 2 to 4 meters. Within the tidal a small strip along the Chattogram-Cox’s Bazar coastline. In these areas, the rivers and the Meghna Estuary, locally generated wind waves occur, but these 50-year wind speed exceeds 280 km per hour (Housing and Building Research are often smaller (1 to 2 meters) due to the limited width of the rivers and the Institute 2018). Further inland, near coastal cities such as Khulna and Barisal, reduced wind speed further inland. the wind speed for this extreme condition is somewhat lower but still very significant (240 km per hour). The Sundarbans mangrove forest dampens the Cyclones can also bring a large amount of rainfall, severely compounding a wind speed for the western part of the coastal zone, resulting in lower extreme cyclone’s impact, although rainfall during the monsoon period is generally wind speeds. higher. The low-lying flat areas in the Meghna Estuary and the western part of the coastal zone often experience high precipitation intensities during cyclone In addition to strong winds, cyclones are accompanied by storm surges striking activity. Since water levels are also elevated and drainage sluices are manually the coastal zone. Storm surges generated by tropical cyclones are further operated, the drainage of excess rainwater during these events is generally amplified close to the coast (especially in the eastern part of Bangladesh), limited, potentially causing waterlogging problems. However, the impact of which can be attributed to the phenomenon of the re-curvature of tropical heavy rainfall during cyclones is most severe in the southeast because of its cyclones in the Bay of Bengal and the shallow, funnel-shaped, coastal shelf that steep topography inland. For example, Cyclone Komen (2015) brought 800 amplify surges (Islam and Peterson 2009; Dasgupta et al. 2010). The tidal phase millimeters of rainfall to Chattogram in three days and 1,000 millimeters to and amplitude are also key factors that determine storm surge levels. Due to Cox’s Bazar over a period of 10 days (Wiltgen 2015), resulting in flash floods the interaction of the aforementioned factors, the Meghna Estuary region has and a number of landslides in the area. experienced the highest storm surges. Typical storm surge levels for severe Chapter 2: Overview and Trends 79 2.2.2. Coastal and River Erosion A dynamic boundary between land and water is a key feature of the coastal zone of Bangladesh. Erosion is the process of inland movement of the land- water boundary, while accretion is defined as land movements in the opposite direction. The dynamics of erosion and sedimentation is the result of a complex interplay between currents and waves, and the transport of suspended (ranging from fine sand to silt and clay) and mobile bed sediments. These dynamics are partly the result of inherent natural dynamics (“free behavior”) but are increasingly driven by human interferences (“forced behavior”) (De Vriend 2003). The land-water boundary can naturally move hundreds of meters per year in some locations in the coastal zone. While a large part of the coastline experiences erosion, some large patches of land have emerged due to a surplus of sediment, in particular in the Meghna Estuary (Brammer 2014). Examples of human-induced impacts in the coastal zone resulting in erosion are dredging activities to deepen port access channels and the construction of coastal and riverbank protections, which interrupt sediment flows. There are three types of erosion in the coastal zone of Bangladesh: tidal riverbank erosion in the Ganges Tidal Plain areas, estuarine erosion in the Meghna Estuary, and shoreline erosion at the exposed coastline. • Riverbank erosion along the tidal rivers in the Ganges Tidal Plains West and East occurs mainly in river bends (Figure 2.12). Erosion here is primarily caused by the regular tidal currents. In the outer bends of the river, the current velocities are high, causing the cohesive sediment to erode because of the hydrodynamic forces exerted on the riverbank. In addition, cyclones and monsoon events can accelerate erosion in certain cases. The typical erosion rate in these river bends can be in the order of 10 meters per year in some cases. • Estuarine erosion in the Meghna Estuary is part of a continuous and S M Mehedi Hasan gradual cycle of delta formation (Sarker, Akter, and Rahman 2013) and is by far the most severe type of morphological change in the entire coastal zone. The large supply of sediment from the GBM river system towards Coastal erosion in coastal Bangladesh. Bangladesh: 80 Enhancing Coastal Resilience in a Changing Climate the estuary results in net accretion, with the estuary mouth building in zone is between 1.5 and 2.4 millimeters per year (Krien et al. 2019). In total, the southward direction at an average annual growth rate of 19 square subsidence is estimated to be approximately 5 to 10 millimeters per year in kilometers (Figure 2.12). During this process, large tidal channels change the coastal zone within the CEIP-I (CEIP-I 2021a), which is in line with estimates course, resulting in considerable land loss. A typical erosion rate in this area found in the literature (Brown and Nicholls 2015; Becker et al. 2020). However, is several tens of meters per year but can well exceed hundreds of meters locally, there can be variations in the subsidence rate. For instance, for the city per year in certain places. of Khulna, the largest part of the city experiences vertical land movements of between +5 millimeters per year (uplift) and -5 millimeters per year (subsidence), • Shoreline erosion along the Bay of Bengal can be seen west and east of while other parts experience up to -17 millimeters per year (subsidence) (see the Meghna Estuary (Figure 2.12). To the west of the Meghna Estuary, Box 2.3). a consistent pattern of slow but structural erosion has been observed over the past few decades. The typical erosion rate in this area is about 2.2.4. Salinity 10 meters per year, with waves and tides reworking the sediment lost. Structural erosion is likely a combination of long-term changes in river flow Saline water intrusion in coastal areas is highly seasonal in Bangladesh due to and sediment supply, and changes in the division of water and sediment the dynamic interaction between freshwater inflow and the salinity intrusion of over the various rivers in the delta. These changes can be attributed to tidal waters in the Bay of Bengal. Soil salinity is driven by salt accumulation in the both human and natural causes, such as SLR, the construction of dams soil because of water salinity, drainage, and evaporation. Water salinity is high upstream, increased tidal asymmetry from the construction of polders, and in the coastal region from the deep inland propagation of the tide, in particular siltation in upstream rivers. East of the Meghna Estuary, there is structural during low river flows (Clarke et al. 2015). Average salinity concentrations of the erosion both south and north of Chattogram, mainly due to wave-induced rivers generally increase almost linearly from October to late May, co-occurring longshore sediment transport. Further south, the coast shows pockets of with the gradual seasonal reduction in upstream freshwater inflow. In 2010, the net erosion as well as accretion. This area experiences alternating periods Soil Research Development Institute stated that 63 percent of coastal land is of accretion and erosion associated with the dynamic coastal environment. affected by soil salinity of various degrees, with major impacts observed within the Khulna and Barisal districts (Figure 2.14). The reduction in freshwater 2.2.3. Subsidence inflow from the Ganges, but also the effects of the construction of the polder system, have increased dry season salinity levels in the western part of the A combination of natural and anthropogenic processes causes structural Ganges Tidal Plain (Figure 2.14). Soil salinity is the dominant factor behind low subsidence in the delta area, although with large spatial variations. Vertical land crop productivity in the exposed areas. Salinity levels of up to four parts per movements are driven by several factors, including tectonics, glacial-isostatic thousand (ppt) are still suitable for farming, but values above five ppt will start adjustment, and subsidence. Natural subsidence occurs from the compaction affecting agricultural yields (Salehin et al. 2018). of young sediments in deltas (Brown and Nicholls 2015). Moreover, human- induced subsidence from groundwater extraction, drainage of organic soils, 2.3. Climate and Socioeconomic Change and the starvation of sediments due to the construction of engineering structures locally (e.g. flood defenses) or upstream (e.g. dams) can accelerate Climate change is responsible for rising temperatures, changing precipitation the sinking of deltas (Nicholls et al. 2021). For instance, it was estimated that patterns, intensifying extreme weather events, and an increase in sea levels. the compaction from sediment loading over the last 11,000 years in the coastal Bangladesh is one of the countries at the forefront of increased risk for climate- Chapter 2: Overview and Trends 81 Figure 2.12: Schematic Overview of Dominant Processes at the Coast Combined with Surface Water Changes Between 1985 and 2016 Reflecting Land Losses and Gains Source: Aqua Monitor, Deltares (http://aqua-monitor.appspot.com/) and based on Donchyts et al. 2016. Note: Green and blue colors represent areas where surface water changes have occurred during the last 30 years. Green pixels show where surface water has been turned into land (accretion, land reclamation, droughts). Blue pixels show where land has been changed into surface water (erosion, reservoir construction). Bangladesh: 82 Enhancing Coastal Resilience in a Changing Climate Box 2.3: Measuring Subsidence from Space Measuring subsidence is often difficult because of the local variations in subsidence rates that require a can be done for areas with stable radar reflectors dense measurement network, and the high cost of installation and maintenance of traditional measurement (such as buildings, bridges) over time by making instruments (leveling or GPS). In recent years, the use of interferometric synthetic aperture radar (InSAR) allows high resolution measurements of the change measuring changes in land surface elevation from space at a high spatial resolution (Solari et al. 2018). This in the position of the reflectors by comparing two radar scans made for the same area but at Figure 2.13: Local Displacement Rates in Khulna, February 2017 to December 2019 different times. The example for the city of Khulna below was derived within the Earth Observation for Sustainable Development Project (European Space Agency 2020), which is an initiative of the European Space Agency. The change in elevation was measured for a period of three years (February 2017 to December 2019), during which 7,900 measurement points were obtained. It was found that 91 percent of the area of interest experiences a change of between -5 and +5 millimeters per year change, 6 percent between -5 and -10 millimeters, and 2 percent more than -10 millimeters per year. The uplift happens close to the riverbanks, while the large subsidence was measured in the western and southern parts of the city (Figure 2.13). Source: European Space Agency 2020. Chapter 2: Overview and Trends 83 Figure 2.14: Salinity Map of the Coastal Zone indicating Soil Salinity Boundar- change-induced hazards. More specifically, it is particularly prone to SLR, more ies for 1973, 2000, and 2009 intensified flooding, and cyclone events. Moreover, the country is expected to experience high socioeconomic growth, leading to increasing pressures on the delta system. This section outlines the key climate and socioeconomic trends in the coastal zone. 2.3.1. Temperature Temperatures are expected to rise, with a stronger rise in winter temperatures. There is agreement among predictions that the average temperature will increase significantly in Bangladesh. Across all climate models included in the Coupled Model Intercomparison Project Phase 5, a warming between 1.2 and 1.9 degrees Celsius is expected by 2050, depending on the emission scenario adopted (relative to 1986-2005). By the end of the century, the temperature is expected to have risen by 1.3 to 3.9 degrees Celsius. However, both the daily maximum and minimum temperatures are changing more rapidly than the daily mean temperature (10 to 20 percent higher). Warming is generally expected to be more pronounced for the winter months (see Box 2.4). By the end of the century, the average temperature will increase between 1.7 and 4.5 degrees Celsius during the winter months (December-February), while warming of 0.6 to 3.4 degrees Celsius is projected for the summer months (June-August). The warming is expected to be relatively uniform across the country (World Bank 2021). As a result, heatwaves are expected to become more frequent. For the country as a whole, the number of days that the critical heat threshold (35 degrees Celsius) is exceeded could potentially double by the 2090s under the highest emission scenario (representative concentration pathway (RCP) 8.5) (World Bank 2021). A Mann-Kendal test of the annual mean temperature shows a likely increasing trend in the coastal zone (Figure 2.15). Source: Soil Resource Development Institute 2010. Bangladesh: 84 Enhancing Coastal Resilience in a Changing Climate Figure 2.15: Trends in Annual Mean Temperature – Mann-Kendal Test 2.3.2. Rainfall and Discharge Rainfall patterns are projected to change, although changes in future precipitation are highly uncertain. Overall, rainfall is expected to increase slightly (5 to 10 percent). However, projecting changes in the onset and magnitude of monsoon rainfall is difficult, given that climate models do not represent the monsoon well (Turner and Annamalai 2012). Using regional climate models, a significant increase in pre- and post-monsoon rainfall is found in previous work (Fahad et al. 2018). There seems to be agreement that light precipitation during the monsoon will decrease, but that this will be offset by an increase in the frequency of high precipitation events (World Bank 2021). In contrast to the temperature projections, regional differences in future precipitation projections are more pronounced. The coastal zone is expected to see only a small increase in rainfall, while further inland, rainfall will increase more considerably (see Box 2.4). The increase in monsoon rainfall will result in larger monsoon river flows reinforced by enhanced glacier melt. Climate-driven changes in the upstream areas of the GBM, both from changing rainfall patterns and melting glaciers, will increase the extreme discharge of the three main rivers. The extremely high flow in the GBM river system, with a discharge threshold that is exceeded 1 percent of the time, is expected to increase by 27 to 54 percent for the Ganges, 8 to 63 percent for the Brahmaputra, and 15 to 81 percent for the Meghna for warming scenarios ranging between 1.5 and 4 degrees Celsius (Mohammed et al. 2018). In particular, the Brahmaputra and Meghna extreme river discharge will increase steeply for the highest warming scenario. For these rivers, the strongest change will be seen for the month of May (Yu et al. 2010). Source: CEIP-I 2021b. Chapter 2: Overview and Trends 85 Box 2.4: Climate Change Projections for Bangladesh show the intermodel range (10th to 90th percentiles), illustrating that larger uncertainties persist and that warming could be considerably higher or lower. Future climate information is derived from a set of global climate models that form the basis for the Coupled Model Intercomparison Project Phase 5. These Compared to the rise in temperature, which is relatively uniform across the models are forced by four different RCPs, which represent the total cumulative country, precipitation changes have distinct spatial patterns. Figure 2.16 shows greenhouse gas (GHG) emissions by 2100 (RCP2.6, RCP4.5, RCP6.0, and RCP8.5). the changes in annual precipitation for the 2040 to 2059 time period (left) and RCP2.6 represents a strong mitigation scenario, whereas RCP8.5 reflects a the 2080 to 2099 time period (right). The north of the country is expected to business-as-usual, or high emission, scenario. see the largest precipitation change, with a possible increase of more than 200 millimeters for the mid-century period and 300 millimeters or more for the end- Table 2.2 shows the projected rise in average temperature for the winter century period. There are mixed signals for the coastal zone. For the mid-century and summer months in Bangladesh for the 2050 to 2059 and 2080 to 2099 time period, the western and southeast coastal zone will experience an increase time periods per emission scenario. For both the mid-century period and the in precipitation, whereas the areas in between will experience limited change. end-century period, the winter months are expected to experience higher For the end-century time period, all areas of the coastal zone will experience an warming compared to the summer months, ranging from 0.6 to 0.9 degrees increase in annual precipitation, with the highest values in the Meghna Estuary Celsius higher warming for the mid-century time period and 0.7 to 1.1 degrees and near Chattogram, whereas the western coastal zone will experience a lower Celsius higher warming for the end-century time period. The values in brackets increase in precipitation. Table 2.2: Changes in the Annual Average Temperature Relative to the 1986 Figure 2.16: Spatial Changes in the Annual Average Precipitation Relative to to 2005 Baseline Period per Season for Different Time Horizons and Climate the 1986 to 2005 Baseline Period for the 2040 to 2059 Time Horizon (left) and Scenarios the 2080 to 2099 Time Horizon (right) Scenario 2040-2059 2080-2099 Jun-Aug Dec-Feb Jun-Aug Dec-Feb RCP2.6 0.6 1.5 0.6 1.7 (-1.1, 2.9) (-0.7, 2.8) (-0.9, 3.2) (0.7, 2.9) RCP4.5 1.0 1.6 1.6 2.3 (-0.6, 3.3) (-0.4, 2.9) (-0.1, 4.2) (0.3, 4.0) RCP6.0 0.7 1.5 1.8 2.9 (1.1, 3.4) (-0.7, 2.8) (0.1, 4.8) (0.8, 4.5) RCP8.5 1.6 2.2 3.4 4.5 (0.0, 4.0) (0.0, 3.8) (1.7, 5.9) (2.4, 6.2) Source: World Bank 2021. Note: The top number is the multimodel mean and the values in brackets show the Source: World Bank 2021. intermodel spread (10th to 90th percentiles). Note: Data is based on the RCP8.5 emission scenario. Bangladesh: 86 Enhancing Coastal Resilience in a Changing Climate 2.3.3. Relative Sea Level Rise Figure 2.17: Averaged SLR Projections for the 21st Century and Associated Uncertainties Relative SLR (RSLR) is greater in Bangladesh than in many other countries, due to the simultaneous rise in the MSL and subsidence in low coastal areas. The current SLR measured at the Bangladesh coast is in the order of 3 millimeters per year, which is larger than the global average (Becker et al. 2020). Predictions indicate that the Bay of Bengal will be subject to SLR ranging between 0.5 and 0.7 meters by 2100 using a mid-level emission scenario (RCP4.5), although this number would be approximately 20 centimeters higher under a rapid warming scenario (RCP8.5) (Jackson and Jevrejeva 2016). This means that 20 percent of the Bangladesh population would be living below the high-tide line in 2100 under the mid-level scenario, while under the rapid warming scenario (RCP8.5), this number increases further to one-third of the population (Kulp and Strauss 2019). Together with the ongoing subsidence in the area, the expected RSLR is in the order of 1 to 1.5 meters at the end of the century relative to present-day levels. Averaged SLR values along the Bangladesh coastline are shown in Figure 2.17 for both the RCP4.5 and RCP8.5 scenarios and include a 5-95 percent confidence interval. Source: CEIP-I 2021b. 2.3.4. Tropical Cyclones The intensity of cyclonic storm surges as well as the hard to predict and differ considerably per model, there seems to be a consensus that the frequency depth and extent of coastal inundation are likely of tropical storms might decrease in the Northern Indian Ocean, but extreme cyclones (category 4 or to increase in a changing climate through rising 5) might increase (Knutson et al. 2020). In addition, the maximum wind speed is expected to increase sea surface temperatures and SLR. Although the between 4 percent and 12 percent, and precipitation between 23 percent and 38 percent (Yoshida et changes in cyclone frequency and intensity are al. 2017). The combination of increasing wind speed and a rise in the MSL along the coast will make the Chapter 2: Overview and Trends 87 occurrence of extreme water levels, and resulting coastal flooding, more likely. Irrigation water with a salinity level of 5 ppt will likely decrease average crop For instance, projections by Jisan, Bao, and Pietrafesa (2018) found that the yields by 25 percent (Clarke et al. 2015). This means that groundwater will need potential inundated area from an event like Cyclone Sidr (2007) or Cyclone Aila to increasingly be used as a source of irrigation water, or alternative agricultural (2009) at the end of the century would increase by 53 percent and 47 percent, practices such as rainwater harvesting, different seed bed shapes and seed respectively, as a result of SLR. In another study (Haque, Kay, and Nicholls placements, and furrow irrigation will need to be adopted (Clarke et al. 2015). In 2018), the extent of future inundation was modeled based on changes in both the past, saline-tolerant rice varieties were adopted by coastal farmers, thereby upstream water levels and SLR, showing that a Cyclone Sidr-like event at the increasing rice production in saline areas (Rabbani, Rahman, and Mainuddin end of the century could raise maximum flood depths by 40 centimeters and 2013). On top of the implications for agriculture, the freshwater habitat of many increase the total inundated area by almost 300 percent. fish species will be affected by changes in salinity. For instance, the optimum surface water salinity is less than 4 ppt for the giant freshwater prawn and 10 to 2.3.5. Salinity Intrusion 20 ppt for the black tiger shrimp (Dasgupta et al. 2015). Changes in salinity intrusion threaten agricultural production and aquatic 2.3.6. Socioeconomic Growth and Economic Transition ecosystems. The increase in SLR and changes in upstream river discharge will also modify the spatial and temporal patterns of salinity intrusion in the coastal Over the course of the 21st century, Bangladesh is expected to grow zone. A study conducted by the World Bank (Dasgupta et al. 2015), which significantly in terms of population and economic output, alongside a structural modeled present and predicted changes in river salinity across the coastal transformation of the economy. Some predict that by 2050, assuming an districts, revealed that salinity will move further inland by 2050, leading to a average growth rate of about 5 percent per year, Bangladesh will become the decrease in areas that are slightly saline (-22 percent) and slightly to moderately 23rd largest economy in the world (PWC 2017). The total population is expected saline (-35 percent), and an increase in river areas that are moderately to highly to increase from 163 million in 2016 to between 177 and 192 million by 2050, saline (+8 percent) and highly saline (+35 percent). Although the whole western depending on the socioeconomic scenario adopted. This population growth coastal zone is expected to experience some change, the most significant is accompanied by demographic changes, in particular a continuing decline changes will be in the Sundarbans and parts of Barguna and Patuakhali, which in fertility, yielding a lower dependency ratio and a larger working population will experience high salinity levels. The area with a salinity level of 4 to 5 ppt, by 2050 (Rigaud et al. 2018). By 2030, almost half the population is expected the critical threshold for agriculture, is expected to increase from a baseline of to live in towns and cities. The growth in population will be accompanied by 1.7 percent to 4.8 or 11.1 percent in 2050, depending on the scenario adopted. an increase in the demand for food. For instance, projections show that by Bangladesh: 88 S M Mehedi Hasan Enhancing Coastal Resilience in a Changing Climate 2050, total rice production will need to increase by 63 to 134 percent to meet growth, moderate to high urbanization, and a decentralized economy with national food requirements (Mainuddin and Kirby 2015). Bangladesh has made high connectivity. The traditional economy scenarios include low GDP growth, significant progress in agricultural productivity growth, mainly in terms of an economy based on low-value industries, centralized urbanization, and poor technological change (World Bank 2016). In the future, it is expected that the connectivity, leading to urban-rural isolation. agricultural sector will transform given the fast-growing demand for a more diverse, sophisticated, and nutritious diet (World Bank 2016). 2.4. Concluding Remarks Bangladesh has the ambition to transition to a more diversified economy with This chapter has highlighted the uniqueness of the coastal zone, which creates better integration into global supply chains. In particular, the technology, IT, many opportunities and challenges given the interaction of the biophysical and garment sectors are expected to grow rapidly. Integral for this transition is and socioeconomic systems. To safeguard the sustainable economic growth private sector investment (foreign direct investment) in small and large-scale of the coastal zone, risk planning is essential to target interventions that are manufacturing and infrastructure. Public infrastructure investment is low (2 effective, cost-efficient, and robust against future changes. Bangladesh is not percent of GDP) compared to some of the country’s regional competitors and starting from scratch; it has a long-standing tradition of putting into place will need to increase to about 10 percent to sustain current growth rates (World measures to reduce the coastal risks for its communities. This chapter has Bank 2016). In order to diversify the economy and promote export growth, both already highlighted various natural and human systems and interventions, inland (such as the Dhaka to Chattogram inland waterway) and international such as mangroves and polder infrastructure, as well as EWS and shelters for (for example, Bangladesh to India) transport connectivity and logistics need to evacuation during cyclones. A thorough understanding of the implementation be improved. and functioning of these interventions, and of the lessons learned to date, is essential to further build resilience. However, before additional measures However, large uncertainties remain with regards to the economic transition can be implemented, risk has to be quantified to understand where and how of the country. The BDP 2100, for instance, uses four plausible scenarios for interventions should be prioritized and designed. Therefore, the next chapters the delta, two in which the delta remains a more traditional economy (more provide an in-depth overview of the risk profile of the coastal zone (Chapter 3), agriculture focused) and two where a more diversified economy is envisioned. and a detailed assessment of key interventions, including an evaluation of their The diversified economy scenarios include high out-migration, high GDP effectiveness (Chapter 4). 2.5. Notes 6. Population numbers are based on the Preliminary Population and Housing Census 2022 (Bangladesh Bureau of Statistics 2022) 7. From a functionality perspective, these sluices (both drainage and flushing) are called “regulators” to allow both drainage and flushing. However, for ease of reference (as per BWDB standard technical specifications), the BWDB identifies these structures separately as drainage sluices and flushing sluices. 8. These numbers are estimated based on the CEIP-I documentation for 10 polders and scaled to the entire polder system of 139 polders. 9. Data from 2017 from the LGED at https://data.humdata.org/dataset/bangladesh-education-facilities-by-lged. This publicly available dataset is likely not complete. 10. Data from Humanitarian Data Exchange Bangladesh. Spatial dataset provided with location data for health facilities data of Bangladesh. The source of the data is LGED and dataset updated by WFP, Map Action and OCHA (last updated on August 15, 2018), link: https://data.humdata.org/dataset/bangladesh-health-facilities-by-lged. This publicly available dataset is likely not complete. 11. Population figures are based on the latest Bangladesh census data (2011) (Bangladesh Bureau of Statistics 2011) projected using the World Bank’s year-wise population growth rate. Chapter 2: Overview and Trends 89 2.6. References Bangladesh Bureau of Statistics and UNICEF Bangladesh. 2014. Bangladesh multiple indicator cluster survey 2012-2013, ProgotirPathey: Final report. Dhaka. Ahmad, S. A., M. H. Khan, and M. Haque. 2018. “Arsenic Contamination in Groundwater Becker, M., Fabrice Papa, Mikhail Karpytchev, Caroline Delebecque, Yann Krien, Jamal in Bangladesh: Implications and Challenges for Healthcare Policy.” Risk Uddin Khan, Valérie Ballu, Fabien Durand, Gonéri Le Cozannet, A. K. M. 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Erosion Risk to People, Land, Infrastructure, and Coastal Amenities 3.3. Risk of Waterlogging 3.4. Climate Migration 3.5. Concluding Remarks 3.6. Notes 3.7. References 94 Bangladesh: Enhancing Coastal Resilience in a Changing Climate 3 Mahfuzul Hasan Bhuiyan CHAPTER 3: RISK PROFILE As described in Chapter 2, the interaction of the biophysical and socioeconomic or the occurrence of natural and climatic hazards. Both climate change and systems in the coastal zone provides many benefits, but also creates various socioeconomic growth are expected to gradually increase the risk over time, risks to the people, infrastructure, and livelihoods. These risks are the result threatening the development ambitions of Bangladesh. of a complex interplay of multiple factors that vary across different parts of the coastal zone. To improve coastal resilience, the drivers of risk need to be Therefore, it is imperative to obtain an overview of the present-day risk profile identified within the local context. Further, risks are not static, but change if of the coastal zone, and to determine the main underlying drivers of change there are changes in the natural landscape, the socioeconomic characteristics, and how the risk might evolve in the future. The four main risks identified in this Chapter 3: Risk Profile 95 report, based on Chapter 2, are risks associated with tropical cyclone impacts, educational and health facilities), which often need a considerable amount of erosion, waterlogging, and climate-induced migration. To quantify any type of time to restore. For instance, the impact of tropical Cyclone Aila (2009) led risk, information on the hazard, the exposure (to people, infrastructure, land use) to breaches of the coastal embankments in Polder 32 that took 11 years to and vulnerability need to be collected and integrated into a comprehensive risk fully restore, causing widespread disruptions to the livelihoods of the polder management framework. Some of these risks can be quantified on a large scale, inhabitants (Box 3.1). Extreme winds can also cause considerable damage to given current risk modeling capabilities, while others are more context specific assets, especially to poor quality houses. During Cyclone Sidr (2007), the major and need detailed local quantitative or qualitative analysis. In this chapter, cause of destruction of houses was storm surge impacts, whereas extreme wind we combine quantitative risk modeling, through analytics that quantified the damaged mostly non-pucca houses, but these were generally quickly repaired present and future cyclone-induced flood risk, and qualitative and descriptive (Government of Bangladesh 2008). evidence to analyze the current and future risk profile of the four main risks identified. A risk modeling approach was adopted to quantify the exposure of people and assets from cyclone-induced inundation for present-day conditions and 3.1. Tropical Cyclone Flood Risk a future climate scenario (see Box 3.2 for technical details). Only the impacts from storm surges were considered here. Moreover, risk was expressed in terms Tropical cyclone impacts are considered the main risk to people, infrastructure, of monetary asset damage only, thereby neglecting the wider economic and and livelihoods, and result in major flood damage, which could increase welfare losses to households, which can be substantial (Verschuur et al. 2020), significantly with climate change. The largest risk is the exposure of people but still hard to quantify in practice. It should be emphasized that the most at- and infrastructure to the impacts of storm surges and extreme wind originating risk areas from an asset damage perspective might not be the same as from from intense tropical cyclones. Cyclone-induced flooding can lead to loss of a welfare perspective, which can bias any decision made based on these risk life and damage to housing and critical infrastructure (such as road, rail, and estimates (Hallegatte and Engle 2019). S M Mehedi Hasan Source: NASA Earth Observatory (Cyclone Bhola 1970) 1970 ‘Bhola Cyclone’ Bangladesh: 96 Enhancing Coastal Resilience in a Changing Climate Box 3.1: Embankment Breach of Polder 32 Figure 3.1: Land Use of Polder 32 Polder 32, located in the west of the coastal zone just north of the Sundarbans, is home to about 40,000 inhabitants. The impact of Cyclone Aila (2009) caused a breach in part of the embankment, leading to inundation of the low-lying polder, which resulted in significant crop damage, asset damage (many people lost their homes), and loss of life (330 deaths). While being repaired, the area was inundated for almost 10 hours each day because of the incoming tide that flooded the area. The flooding damaged the hydraulic structures, leading to internal drainage congestion and saline water entering the polder area (see Figure 3.1) (Bangladesh Water Development Board 2013). Despite the efforts of the GoB to close the breach with temporary measures, which turned out to be extremely challenging given the ever-changing hydrodynamics at play; it was not until 2020 that the breached embankment was closed (referred as the Nalian closure) by the GoB as part of CEIP-I activities. This event highlights the importance of having reliable coastal protection works to protect people and assets, but it also illustrates that relying solely on coastal protection works is not enough, as failure can lead to large-scale losses. Therefore, residual risks can be significant and need to be accounted for and effectively managed in large-scale DRR portfolios. Source: CEIP-I project documents. Note: Waterlogged areas are the result of the breach of the embankment system after Cyclone Aila in 2009. Chapter 3: Risk Profile 97 Box 3.2: Modeling of Cyclone Flood Risk To evaluate the exposure of assets and people and estimate Improved-Terrain (MERIT) digital elevation model (DEM). Figure 3.3 shows the extent of cyclone flood risk, a detailed modeling framework was developed. inundation in the coastal zone for present and future 10-year and 100-year events. The risk analysis consisted of the following elements: (1) hazard modeling using present-day and future climatic boundary Digital elevation models, such as the MERIT DEM, have known inaccuracies in the low-lying conditions, (2) creating an asset inventory, (3) analyzing the coastal zone of Bangladesh. For instance, a study using another DEM that corrected some of exposure and the damages as a result of exposure of assets, the inaccuracies in the existing DEM showed that the low-lying coastal zone might actually and (4) estimating risk by integrating the probability of hazard be lower than previously thought, which could lead to an underestimation of the potential occurrence and the resulting damages. In this analysis, only the risk of cyclone-induced flooding is considered. Damages as a Figure 3.2: Clustering of Inundation Levels for Cyclone Flood Risk Analysis result of extreme winds and waves are not included. Present and future hazard modeling Scenarios of storm surges along the coast and in the tidal channels were estimated based on the output of a detailed hydrodynamic numerical model for the coastal zone developed by the Institute of Water Modelling (IWM) (CEIP-I 2018). This model used observed wind speed and central pressure data from historical tropical cyclone events to force the hydrodynamic model for the whole area. The model is able to simulate how these storm parameters translate into storm surges and waves, and how they propagate into the tidal channels. By running multiple simulations for different extreme conditions, multiple storm surge hazard output can be generated. Within this work, three simulations were run for both the present and future scenarios. The three simulations correspond to 10-, 25-, and 100-year cyclone events. For the future scenario, an SLR value of 0.5 meter was added to the hydrodynamic model, and wind speeds were assumed to increase by 8 percent. Storm surges are clustered at the upazila level for the analysis. An example of this clustering is illustrated in Figure 3.2. The output of the storm surge model is overlaid with the Source: Analytics performed by the World Bank for this report using data from CEIP-I 2018. Note: This example shows the modeled (red) and clustered (blue) storm surge values at the upazila level elevation of the coastal zone based on the Multi-Error-Removed for a once in 25-year storm surge event. Bangladesh: 98 Enhancing Coastal Resilience in a Changing Climate inundation (Kulp and Strauss 2019). This has been confirmed by more recent Asset inventory work that used LIDAR elevation data, with a much higher vertical accuracy An asset inventory and land-use map for the coastal zone was assembled, which (though lower spatial resolution) and showed that the elevation of the includes all roads, railways, educational facilities, health facilities, agricultural Bangladesh coastal zone might be lower than estimated using freely available areas, economic zones, and housing. This inventory comprises all assets that DEM products (Hooijer and Vernimmen 2021). However, inundation is not only are potentially at risk. The housing units were determined separately by type of a function of elevation but also of storm surge levels, which are also uncertain. housing (pucca, semi-pucca, kutcha, jhupri), since different housing types have Therefore, it is difficult to say whether or not the inundation maps are over- or different vulnerabilities (because of the quality of the housing) and damage underestimating the potential risk. values (because of the reconstruction costs). The location of houses is also used as a proxy for population exposed. Figure 3.3: Inundation Depth Maps for the Baseline and Future Scenarios Exposure analysis The inundation maps were overlaid with the location of the assets. The inundation and the physical vulnerability of the asset determine to what extent a specific asset will be damaged as a result of inundation. Physical vulnerability thus refers to the expected damage to physical structures from a hazard ranging from zero (no damage) to one (full destruction). This was combined with the reconstruction cost of each of the assets, which is equal to the amount of money that is needed to restore the asset to its original pre-disaster condition (expressed in US$ per m2). To estimate the physical vulnerability, depth- damage functions were used, which translate the depth of inundation to the expected damages of the asset or land-use class. Asia-specific depth-damage curves and reconstruction values for the different asset types were obtained from previous work (Huizinga, De Moel, and Szewczyk 2017). The maximum damage values were corrected for inflation (as they were expressed in 2010 prices) and converted from Euros to US dollars. Several correction factors were applied to the damage calculation. Buildings in semiurban and rural areas were considered to be of lower quality and less expensive to rebuild. Therefore, rural houses were considered to be 25 percent of the value of urban houses, and semiurban houses were assumed to be 60 percent of the value of urban houses. For roads, the damage was scaled to the width of the road, which is different for highways (4 meters), zila and upazila Source: Analytics performed by the World Bank for this report using data from CEIP-I roads (3.7 meters), and union and village roads (3 meters). The exact location of 2018, and MERIT DEM (http://hydro.iis.u-tokyo.ac.jp/~yamadai/MERIT_DEM/). Note: The top panels show a 10-year storm surge event, and the bottom panels show a housing and population is not known. Therefore, it was assumed that exposure 100-year storm surge event. scales linearly with the fraction of land inundated per upazila (for example, 50 Chapter 3: Risk Profile 99 percent of land inundated means that 50 percent of housing and population Figure 3.4: Ratio of Damages per Upazila for the Climate Change Scenario is exposed). A similar approach was followed for estimating agricultural losses, versus the Baseline Scenario with the area of agricultural land per upazila taken as the maximum area that can be damaged. To estimate impacts to industrial areas, an outline of the SEZ was taken and then it was assumed that industrial facilities cover only a fraction of that land. The maximum damage values were multiplied by 50 percent to account for this. The protection levels of the existing embankment system were taken into account. Sixty percent of the exposed coastal upazilas have protective structures in place, which protect against storm surge levels equivalent to a 10- year event (for the baseline scenario). However, for future storm surge events, these polders may only offer partial protection against a 10-year event. Here it was assumed that the flood protection will not fail, even at higher return periods, and that the damages scale with the difference between the damages from a given extreme cyclone event and the damages associated with a 10- year event at present. Hence, in some upazilas, the future scenarios will only marginally increase the damage, whereas in other upazilas the damage will increase sharply with an increase in extreme water levels, as can be seen in Figure 3.4. To determine whether the modeled damage values are realistic, a comparison Source: Analytics performed by the World Bank for this report using data from CEIP-I 2018. Note: The ratio is found by calculating the damages for a 10-year event assuming no between the reported damages after Cyclone Sidr (2007) and the modeled protection standards in place. damages was performed. For every coastal district, the return period corresponding to the observed water levels was taken and the damage (corrected Risk analysis and risk correction for the presence of embankments) estimated. The aggregated coastal-wide The risk expressed in expected annual damages was found by integrating the damage value was compared to the asset damages reported in the damage, damage associated with the different return periods. The trapezoidal rule was loss, and needs assessment report for Cyclone Sidr (Government of Bangladesh used to perform this integration, resulting in an aggregate asset risk value per 2008). The reported damages were corrected for inflation, and it was further upazila. This upazila-level risk map is included in Figure 3.5 showing the risk assumed that of the total reported damages, approximately 75 percent were for both the baseline and the future scenarios. associated with storm surge induced flood damage (with the remaining being caused by extreme wind speeds). This comparison resulted in a correction factor equal to 0.67 (that is, the modeled damages were overestimated), which was applied to the resulting risk values. Bangladesh: 100 Enhancing Coastal Resilience in a Changing Climate The future scenario includes a 0.5-meter SLR scenario, equivalent to the followed by roads and industrial areas. The total damages for a 10-year event, conditions likely to occur in the second half of this century, and wind speeds a 25-year event, and a 100-year event are expected to increase by 59.8 percent, that are 8 percent stronger than under present-day conditions. Three flood 61.4 percent, and 43.3 percent, respectively (without considering protection), as events were compared, reflecting the inundation associated with a 10-year, a result of climate change. At the moment, the current elevation of the polders a 25-year, and a 100-year cyclone flood event.12 The assets considered in should protect the assets within the polder from flooding under the baseline this analysis include houses, roads, railways, educational facilities, healthcare 10-year storm surge event. Thus, although the embankments prevent damage facilities, agricultural land, and economic zones. for a 10-year storm surge event under the baseline scenario, damages will likely increase rapidly when no further adaptation measures are taken. Damages At present, 6.4 percent of the coastal population are exposed to a 10-year are not equally distributed across districts, as can be seen in Figure 3.5. The flood event, which could increase to 10.2 percent in the future scenario. For damage is highest in the populated areas of Khulna, Chattogram, and Cox’s the 100-year event, 27.3 percent of the coastal population are exposed to Bazar, and for the coastal upazilas. The spatial differences become even more flooding under present climatic conditions, and 34.5 percent in the future. The pronounced for the 100-year event, with a clear divide in damages between the breakdown of damages per asset type and return period is shown in Table exposed and interior coastal zones. 3.1. The largest damage is from damage to households and agricultural land, Table 3.1: Expected Damages by Asset Type, Baseline and Future Return Period Flood Scenarios Households Economic Agriculture Educational Healthcare Roads Railways Total Zones Facilities Facilities Damages (US$ million) Baseline 10 year 1,321.6 224.6 1,271.2 20.5 2.3 336.0 2.0 3,178.2 25 year 2,617.1 502.2 2,671.7 47.0 4.7 841.6 5.8 6,690.1 100 year 5,925.2 1,596.2 5,224.7 127.4 10.7 1,833.2 13.2 14,730.6 Future 10 year 2,073.9 393.2 2,051.7 35.7 3.6 515.6 3.7 5,077.4 25 year 3,990.5 943.0 4,497.1 92.0 7.3 1,262.4 7.8 10,800.1 100 year 7,892.6 2,143.1 7,536.9 169.6 10.8 3,338.8 17.5 21,109.3 Source: Analytics performed by the World Bank for this report. Chapter 3: Risk Profile 101 Figure 3.5: Estimated Asset Damages per Upazila for the Baseline and Future Storm Surge Scenarios for million per year under the baseline scenario, Different Return Periods, Assuming No Protection which is expected to increase to US$570 million per year (a 90 percent increase) in the future because of changing climatic conditions. Some upazilas face a higher level of risk than others. The spatial distribution of risk is shown in Figure 3.6 for the baseline and future scenarios. Under the baseline scenario, eight upazilas— in Noakhali (Hatiya, Subarnachar), Chattogram (Mirsharai, Bakalia, Chandgaon, Hathazari, Sandwip), and Patuakhali (Galachipa) districts—face a very high level of risk (more than US$25 million per year). The high levels of risk in Chattogram and Cox’s Bazar districts are driven by the high concentrations of assets, while Noakhali and Patuakhali districts have high levels of risk as a result of the high inundation levels that could be reached in those areas. In Khulna district, inundation is caused by the propagation of storm surges inland, potentially flooding a large number of assets. Under the future scenario, an additional eight upazilas will face a very high level of risk. Among the upazilas that already experience a large risk under the baseline scenario (the Source: Analytics performed by the World Bank for this report. top 15 upazilas), the most climate sensitive Note: The top panels show a 25-year storm surge event, and the bottom panels show a 100-year storm surge event. are three that will experience a risk increase of more than 100 percent under the future The aggregate asset risk per upazila is found by integrating the probability of occurrence and the resulting scenario—Galachipa upazila (Patuakhali) damage to infrastructure assets for the various flood hazards. Risk is expressed as the expected annual damage with a 123 percent increase, Amtali (Barguna) in US dollars per year. Across the coastal zone, the risk from cyclone-induced flooding is equal to US$300 with a 124 percent increase, and Char Fasson (Bhola) with a 112 percent increase. Bangladesh: 102 Enhancing Coastal Resilience in a Changing Climate Figure 3.6: Aggregate Asset Risk from Cyclone-Induced Coastal Flooding, Baseline and Future Scenario Source: Analytics performed by the World Bank for this report. Risk to infrastructure assets does not cover the entire spectrum of losses. A 2018). Although predicting these welfare losses is tricky, some studies show that proportion of the exposed population might lose their lives if they do not every dollar in asset losses results in an average of 1.5 dollars in welfare losses, evacuate in time, or do not evacuate at all. However, this is particularly difficult although this number can be much higher for poorer households (Hallegatte, to estimate and therefore has not been taken into consideration here. In Bangalore, and Vogt-schilb 2016; Verschuur et al. 2020). Welfare losses could addition, losses of infrastructure can lead to wider welfare losses to households, increase in the future because of SLR and population growth, but they could as people derive income from the services that infrastructure and productive also decrease because of improvements in welfare, in particular increased assets provide. Poor households could be disproportionately affected by this, as access to financial products, improved housing, and higher household wages, they have fewer financial means (such as savings or insurance) to recover from from a transition out of agriculture for some households (Verschuur et al. 2020). an income shock (Hallegatte and Rozenberg 2017; Hallegatte, Fay, and Barbier Chapter 3: Risk Profile 103 3.2. Erosion Risk to People, Land, Infrastructure, and Coastal respondents mentioned that they had to take their child out of education (91 Amenities percent), reduce their food intake (94 percent) or internally displace, migrate, or become homeless (Rahman and Gain 2020). On the other hand, large accretion Erosion in some parts of the coastal zone could have major impacts on people, in other areas, sometimes accelerated by the construction of cross-dams, has land, infrastructure, and coastal amenities. Land is scarce in the coastal zone resulted in significant land gains, most notably in the Meghna Estuary. The and therefore valuable. High erosion rates, as experienced in some parts of the net economic gain or loss is determined by the economic value of the land coastal zone, can lead to significant loss of land (see Box 3.3 and Figure 3.7). lost to erosion and the opportunities newly accreted land offers. Currently, the Examples of erosion hotspots in the coastal zone are shown in Figure 3.8. accreted land is only sparsely populated and mainly used for resettlement and afforestation activities. In addition, erosion can lead to significant impacts on the livelihoods of the people that live on that land or derive income from it. In Bangladesh, erosion Erosion can also have large impacts on the stability of coastal infrastructure. has mainly affected poor small landowners that are bound to these at-risk areas Monsoon and tidal river flows have led to the erosion of embankments and (Hutton and Haque 2004; Rahman and Gain 2020). For instance, a field survey slope and bank protection works at several places in the coastal zone, mainly looking at the impacts and coping strategies of households affected by riverbank along inland river channels. According to a recent study that analyzed the erosion in the Koyra riverine area in 2017 and 2019 (Khulna district) showed movement of the river network in the coastal zone using satellite imagery, the that 83 percent of the interviewed households reported that their house was migration rate was on average 47 meters over 30 years, although it was more severely damaged by erosion (Rahman and Gain 2020). As a coping strategy, than 500 meters over 30 years in some places (Jarriel et al. 2020). A quarter of Mahfuzul Hasan Bhuiyan Bangladesh: 104 Enhancing Coastal Resilience in a Changing Climate Box 3.3: Bhola Island Change in Land Area Bhola, the largest island in Bangladesh, is located in the Meghna Deltaic Plain, accretion has also taken place as a result of, among others, the construction of and surrounded by the Meghna River in the north and east, and the Tetulia various cross-dams in the 1990s, although the land gain is small compared to River in the west. The population of approximately 1.7 million live mainly the land lost. Various plans have been proposed to design additional structural along the edges of the island (Biswas and Islam 2020). Since 1990, erosion protection measures in the erosion-prone regions, including an erosion early has become prevalent along the island’s shoreline, particularly on the eastern warning system (EEWS). The EEWS includes the monitoring of erosion along side. Erosion accelerated over the 2003-2015 period (Figure 3.7), with a land large stretches of protection works using sensors embedded in the design. This loss equivalent to 7,324 hectares over this period. The major erosion hotspot is combined with underwater acoustics to detect faults and weak points in the is the stretch of shoreline of about 130 kilometers in the east that erodes at submerged bank and toe protection at an early stage, which is difficult in the a rate of 5 to 10 square kilometers per year, destroying fertile land, houses, operation and maintenance (O&M) of traditional protection works. and embankments, resulting in forced migration as livelihoods are lost. Some Figure 3.7: Change in the Land Area of Bhola, 2003 to 2015 Source: Map developed by the World Bank for this report using Landsat 7 and Landsat 8 satellite imagery based on description in Biswas and Islam 2020. Chapter 3: Risk Profile 105 S M Mehedi Hasan Bangladesh: 106 Enhancing Coastal Resilience in a Changing Climate the channels migrated more than 60 meters over the last 30 years, underlining the scale of the channel migration issues that might occur, and the widespread risk to coastal infrastructure. Although in some cases the embankments are left to erode, with a new embankment constructed further inland, in other cases, engineering solutions are applied to protect the embankment against erosion, often at large costs (Nazrul Islam, n. d.). For the coastal embankments, episodic erosion during cyclones, although often short-lived, can affect the toe and slope structures of the embankments. Finally, structural erosion of coastlines can diminish the coastal amenities these systems provide. Healthy sandy shorelines buffer against storm events and provide benefits for human recreation, tourism, and ecosystems (de Schipper et al. 2021). Therefore, preserving these sandy beaches is essential to meeting the GoB’s ambition to grow the tourism sector in the coastal zone. Maintaining Ismail Ferdous sandy ecosystems goes hand in hand with the preservation of other coastal ecosystems, such as mangrove forests. Deltaic areas are continuously changing and will continue to do so in the future. Predicting how the risk of erosion in the coastal zone might change in the future is difficult, given the complexities with regard to the morphodynamics and the interactions between humans and the environment. For instance, some studies predict that the sediment supply of the GBM rivers to the coastal zone will decline in the future as a result of climatic and socioeconomic changes and the construction of dams upstream (Dunn et al. 2018). Given the estimated growth in population, and the planned transition to a more diversified economy, including tourism, the need for coastal land and the coastal services and amenities it provides will only increase in the future. 3.3. Risk of Waterlogging Waterlogging, the seasonal or permanent inundation of polder areas, is a widespread problem in many of the polders, although with varying underlying factors. The drainage of excess water from the polder systems has become S M Mehedi Hasan increasingly challenging over the past few decades because of changing conditions inside and outside the polders. This is especially true for the Chapter 3: Risk Profile 107 southwestern districts (Khulna, Satkhira, Jashore districts) and Noakhali district Among others, insufficient drainage, lack of management, siltation of rivers, (see Figure 3.9) In total, 30 percent of polders are experiencing waterlogging and reduced upstream river flow have been identified as possible causes of issues. Long-lasting waterlogging results in social disruptions (from flooding of waterlogging (Alam, Sasaki, and Datta 2017). For instance, waterlogging can schools, health facilities), income loss (from decreasing agriculture), transport be caused by the siltation of the drainage canals within the polder area from disruptions (from flooding of roads), social unrest, and an accelerated transition sediments that have drained into the canals. This siltation blocks the water from agriculture to shrimp farming (FAO 2015). See Box 3.4 for more details on flow through the drainage network, making it harder to flush water out of the the impacts waterlogging has on livelihoods in the coastal zone. polder through the drainage structures (Alam, Sasaki, and Datta, 2017). The underlying causes of waterlogging do, however, differ per polder. In Khulna, for instance, surveys in three polders illustrated that the lack of silt removal, water Figure 3.8: Examples of Erosion Hotspots in the Coastal Zone of Bangladesh between 2000 and 2020 Source: Prepared by the World Bank using Google Earth Pro satellite images based on FAO 2015. Bangladesh: 108 Enhancing Coastal Resilience in a Changing Climate flow reduction in the canals, and encroachment of the canals were the main excess water (Wilson et al. 2017). In the Noakhali region, a major factor has causes of waterlogging (Alam et al. 2016). been the construction of several cross-dams for land reclamation purposes (Rashid, Hossain, and Islam 2013). As a result, the pathways for drainage have Changes outside the polders can also impede drainage. Parts of the Ganges become much longer, worsening the drainage capacity of these areas. However, Tidal Plain West have seen a reduction of freshwater inflow during the dry as mentioned previously, the underlying drivers of waterlogging are complex season from the Ganges and a reduction in the tidal prism (the volume of water and often associated with multiple factors, making it hard to attribute the issue moving through the river between high and low tides). For instance, in the to a single driver only. Pussur catchment, the tidal prism has decreased by over 1 billion cubic meters since the construction of the embankments, resulting in an increase of the tidal How waterlogging might change in the future is still unknown. RSLR could reduce range and siltation of the channels (Pethick and Orford 2013). Increasing water the time window for gravity drainage, which can exacerbate waterlogging issues levels have in turn reduced the time window of low water periods for draining in areas that already experience shorter periods of low water levels. While some issues can be resolved by improved O&M of water management infrastructure, external issues are harder to counteract, which means that sustainable solutions Figure 3.9: Map of the Polders in the Coastal Zone that Experience Waterlogging need to be found to adapt the water management system to these changing Issues conditions. 3.4. Climate Migration Climate-induced migration is expected to increase in the future, although the spatial patterns are still largely unclear, with some studies showing a net out- migration while others predict a net in-migration. Although climate-driven migration is not widespread at present, it is expected to become more prevalent in the future. Rising soil salinity, permanent inundation of land because of SLR, changing crop productivity due to changing temperature and rainfall patterns, and changing economic activities (such as an increase in manufacturing) have been identified as the main drivers of future climate migration (Chen and Mueller 2018; Rigaud et al. 2018). For example, Chen and Mueller (2018) found a direct relationship between an increase in salinity levels and a drop in crop revenue, resulting in some households deciding to migrate. In their study, they predicted that an increase in salinity (from the first to the fifth quantile) will cause 140,000 people to move within their district (to cities like Khulna and Chattogram), and 60,000 people to move to other districts, mostly to Dhaka or other coastal districts. They posit, however, that the attractiveness of shrimp farming under high salinity levels may offset some of the migration, in particular Source: Khan 2018. international migrants. In a study by Rigaud et al. (2018), future migration Note: The light blue areas are the coastal polders that experience waterlogging issues. Chapter 3: Risk Profile 109 Box 3.4: Livelihoods Impacts of Waterlogging patterns as a result of both SLR and changing crop productivity were evaluated for the country as a whole. The researchers found that 2 to 7.5 percent of Waterlogging can have multiple impacts on the livelihoods of affected the population, depending on the climate and socioeconomic scenario, will households. In the early 1990s, a hundred thousand hectares of land in Khulna, become internal climate migrants by 2050. In the most pessimistic scenario, Jashore, and Satkhira became waterlogged. Waterlogging was particularly the population density along the coast could decrease by up to 40 percent, prevalent after the 2011 monsoon season, which affected an estimated 1 except in the southwestern corner of the coastline and near Chattogram, where million people in the three districts. Flood water stayed in the polder for 60 to an increase in population was projected. Figure 3.10 shows the predicted net 90 days, although some places became permanently waterlogged, affecting migration per land-use type in Bangladesh under different scenarios. A large approximately 130,000 hectares of cropland (Awal 2014). In total, about 34,000 migration flow from rainfed cropland to dense settlements is predicted under houses were fully damaged and 58,000 houses were partially damaged (Awal all scenarios for 2050, although the absolute numbers are considerably smaller and Islam 2020). for the climate-friendly scenario (RCP2.6 and shared socioeconomic pathways (SSP) 4). The rice growing regions, which cover most of the coastal zone, will Apart from the direct impacts to cropland and houses, waterlogging can experience a net out-migration under the pessimistic climate scenario (RCP8.5 affect the wellbeing of polder inhabitants in other ways. For instance, a survey and SSP4), while in the other two scenarios these areas will experience a net among households in three waterlogged polders showed that 85 percent of in-migration or limited change in population (Rigaud et al. 2018). the interviewed households reported that waterlogging severely affected their lives and livelihoods, in particular by damaging crops or causing a delay in crop cultivation (Alam, Sasaki, and Datta 2017). Moreover, the stagnant water results in transportation and communication disruptions for large parts of Figure 3.10: Predicted Net Migration Numbers by Land-Use Type in 2020 and the year, often making schools inaccessible. Food prices rose during the 2011 2050 for Various Climatic and Socioeconomic Scenarios waterlogging event, and latrines and drinking water sources were affected (from the inundation of tube wells). As an adaptation strategy, some farmers transformed their waterlogged fields into fishponds, while others had to change jobs or became jobless. For instance, in Bhutiar Beel, more than 37,000 farmers became day laborers as a result of the waterlogging in this area (Awal and Islam 2020). A detailed household survey among affected and unaffected households in Satkhira showed that affected persons had significantly lower expenditures than unaffected persons within the same wealth group (approximately 75 percent of the level of unaffected persons’ expenditures) (FSC 2014). Thus, measures that reduce waterlogging not only result in a reduction of damage to crops and housing but can also have wider positive impacts on the wellbeing of affected inhabitants. Source: Rigaud et al. 2018. Mahfuzul Hasan Bhuiyan Chapter 3: Risk Profile 111 The two studies referenced above mainly focus on the environmental factors 3.6. Notes that cause people to migrate. Other studies state that coastal out-migration may be overpredicted given that large-scale migration to urban areas leads to an 12. A 10-, 25-, or 100-year event refers to an event with a 10%, 4%, or 1% annual exceedance probability of happening every year, and should not be confused with oversaturation of labor and housing markets, resulting in a net migration to the an event happening only once every 10, 25, or 100 years. In fact, a 100-year flood high-risk coastal zone. This effect was taken into account in another study that event that happened last year can happen again before the end of the century, or looked at migration flows in 2100 as a result of SLR and demographic changes even next year. Please refer to https://www.gfdrr.org/en/100-year-flood for more (Bell et al. 2021). This study showed that out-migration will likely not take place information on this. in the coastal zone, and in fact predicts a net in-migration to the coastal zone. This is mainly associated with the economic transition from agricultural to non- 3.7. References agricultural sectors, thereby attracting migrants to the coastal cities for work. Alam, M. S., N. Sasaki, and A. Datta. 2017. “Waterlogging, Crop Damage and Adaptation The districts with the largest in-migration also have large “trapped” populations, Interventions in the Coastal Region of Bangladesh: A Perception Analysis of referring to households that lack access to credit and hence are constrained in Local People.” Environmental Development 23(February): 22–32. Elsevier Ltd. their decision to migrate. However, most of the studies neglect any type of doi: 10.1016/j.envdev.2017.02.009. adaptation or policy interventions that could prevent or steer migration. 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Hutton, D. and C. E. Haque. 2004. “Human Vulnerability, Dislocation and Resettlement: Adaptation Processes of River-Bank Erosion-Induced Displacees in Bangladesh.” Disasters 28(1): 41–62. doi: 10.1111/j.0361-3666.2004.00242.x. Chapter 3: Risk Profile 113 EMPIRICAL EVIDENCE ON SELECTED COASTAL RESILIENCE INTERVENTIONS 4.1. High-Level Assessment of Coastal Interventions 4.2. Flood Prevention and Embankments 4.3. Shoreline Stabilization 4.4. Cyclone Shelters, Early Warning, Evacuation Roads, and Awareness Raising , 4.5. Institutions and Policies for Coastal Zone Management 4.6. Lessons Learned from the Assessment of Past Projects 4.7. Notes 4.8. References Bangladesh: 114 Enhancing Coastal Resilience in a Changing Climate CHAPTER 1 02 Ismail Ferdous CHAPTER 4: EMPIRICAL EVIDENCE ON SELECTED COASTAL RESILIENCE INTERVENTIONS Over the years, Bangladesh has undertaken significant efforts to develop an For example, a series of polders have been constructed to reduce the risk of tidal inhabitable, productive, and resilient coastal zone. Within a relatively short flooding and saline water intrusion while boosting agricultural production. Many timeframe, about 60 years, a DRR portfolio of both structural and non-structural of these polder projects included the construction of major water infrastructure interventions13 has been implemented in Bangladesh through a wide variety of such as embankments, drainage sluices, and canals, as well as roads on top of projects and programs. In effect, noteworthy improvements in terms of EWS the embankments to improve connectivity in the coastal zone. A vast network and last mile connectivity, disaster preparedness and response, and improved of erosion control structures has been designed to better control the highly livelihoods activities, which have led to a reduction in the loss of life and assets, dynamic coastal and tidal river movements. In addition, thousands of shelters has made Bangladesh a global leader in DRR and climate change adaptation. have been constructed over the past few decades to reduce the vulnerability Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 115 of the coastal population during cyclones. Non-structural interventions such Additionally, modeling was carried out to reevaluate the benefits of some of as raising awareness and improving preparedness in combination with early the key interventions. Combining the qualitative information gathered with warning have also been part of the strategy to increase the resilience of the the quantitative modeling outcomes enabled the evaluation of the expected coastal population. Furthermore, the GoB has improved the governance of performance of these projects so as to draw conclusions on lessons learned for integrated coastal planning and has been a global initiator of community- future investments. based disaster risk management. This chapter highlights that based on the assessments done, embankments Since Independence, Bangladesh has invested over US$10 billion in the and shelters in combination with EWS are proven interventions for reducing development of disaster mitigation and preparedness systems in the coastal the risk from cyclones in the coastal zone, and thereby have improved the zone (World Bank 2013). Given the large investment needed to improve livelihoods of millions of people. In addition, strategic mangrove restoration coastal resilience in Bangladesh in the future, it is imperative to evaluate the has been successful in stabilizing the coastline in the targeted areas. However, effectiveness of these interventions, learn from past experiences, and identify to date, mixed success has been achieved in tackling severe coastal erosion. The key focal points to guide future investment plans. evaluation of past interventions found that they were not always embedded in a long-term strategy, and thus, could be better aligned with existing policies (such This chapter provides an integrated assessment of past and current as land-use regulations) and broader development outcomes. Another finding interventions in Bangladesh aimed at identifying lessons learned from these is that interventions should make better use of state-of-the-art knowledge (for projects, which will ultimately help to inform the design of future interventions example, taking a risk-based approach in planning, design, and maintenance). (see Box 4.1). The results of the assessment, along with relevant experience In the next chapters (Chapters 5 and 6), some of these key findings are explored from other countries, are used to present a case for building coastal resilience in more detail and newly developed work on nature-based and hybrid solutions in a meaningful and effective manner. The focus is on interventions that are are presented that can partly solve the aforementioned shortcomings and pave intended to reduce vulnerability against coastal erosion and cyclone-induced the way towards improved resilience in the coastal zone. winds and storm surges, which have been identified as the most prominent hazards and the key threats in the coastal zone (see Chapter 3). 4.1. High-Level Assessment of Coastal Interventions For this purpose, projects were screened and classified according to their risk Different types of interventions have been developed and implemented in the reduction potential (see the cascade of coastal resilience strategies in Box coastal zone of Bangladesh to reduce the risk of coastal hazards. Examples 4.1). This initial screening process was followed by an in-depth assessment of range from multipurpose cyclone/flood shelters, hydrometeorological a selection of interventions covering nine projects using interviews with key services enhancements, early warning and dissemination systems, and coastal stakeholders, field visits, and literature studies, resulting in the identification of embankments to community-based disaster risk management and strategies four key intervention categories: (1) flood/tidal/storm surge protection works, to improve coastal governance. For the high-level assessment, a set of criteria (2) shoreline stabilization works, (3) cyclone EWS and emergency shelters, and was applied to select appropriate interventions for evaluation. The focus was on (4) efforts to improve integrated coastal zone management. This in-depth large coastal projects (at least US$1 million, but preferably larger) implemented assessment helped to identify the performance and impact of past interventions after 1950, resulting in a set of 36 projects for which sufficient information could with respect to coastal resilience and cost-benefit ratios. be found. This set of projects represented a total investment of US$4 billion, which is likely a low-end estimate since not all budgets could be traced. The Bangladesh: 116 Enhancing Coastal Resilience in a Changing Climate Box 4.1: Steps in the Assessment of Ongoing and Historical Projects The factual bases of the projects identified were recorded in factsheets, covering, among others, To be considered relevant for this analysis, the current and historical projects had to meet the following criteria: their objectives and targets, sustainability aspects, success and failure factors, and lessons learned. • The project should be located in or focused on the coastal zone either on land or at sea, up to approximately the 5m+MSL line; A high-level assessment of the projects was en- • The project objectives should at least partly relate to coastal risk reduction; hanced by an in-depth assessment of a subset • The project should be sufficiently large (at least US$1 million but preferably larger); and of projects, aimed at deriving concrete lessons • The project should have started after 1950. learned. The tools for the in-depth assessment included detailed analysis of available documents Figure 4.1: Overview of Methodology for Review of Interventions and interviews with key stakeholders (see Figure 4.1). The assessment of the strategies using multiple analytical approaches—literature reviews, inter- views, and modeling—enabled triangulation of the same phenomenon, namely interventions that enhance (or are supposed to enhance) coastal re- silience, overcoming the weaknesses and intrinsic biases that come from single method, single ob- server, and single theory studies. Source: World Bank 2021. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 117 CHAPTER 4 02 majority of these projects (26) were implemented Table 4.1: Assessment Criteria and Subcriteria for the Multicriteria Analysis after the year 2000 and most of the projects were Criteria Subcriteria donor funded. Effectiveness Storm surge risk Reduction in expected annual number of affected people Reduction in expected annual number of fatalities A multicriteria analysis was used as an assessment Reduction in average annual losses framework to make a comparative high-level Coastal erosion Reduction in annual coastal retreat (structural erosion) overview of all interventions. The framework risk Reduction in event-driven coastal retreat was designed to capture the main components Wind risk Reduction in average annual losses of each intervention or project and enable a characterization of each of them. The framework Sustainability Environmental Ecosystem and biodiversity effects values contained criteria and subcriteria (Table 4.1) Energy efficiency that provided an indication of the performance Ambient environment/spatial quality and contribution to resilience of each selected Carbon emissions intervention. Social values Resettlement/impacts on marginalized groups Local employment/livelihoods improvement There are various ways to classify how coastal Effect on gender conditions interventions contribute to risk reduction. For this Human health report, a “cascade of coastal resilience strategies” Effect on cultural, historic, archaeological sites and landscapes was adopted, which reflects a logical cascading Economic Cost effectiveness values sequence for evaluating the risk reduction Cost-benefit ratio measures. The cascade starts at the source of the Direct effects on local or regional economy (e.g. tourism, agriculture, fishery, logistics, energy) hazard, followed by the pathways that affect the Co-benefits, synergies, or spin-off effects on other sectors’ revenues (e.g. exposure of assets and population, and ends with transportation) the receptor of the hazard (see Figure 4.2). The Implementa- Success/ failure • Funds/finance, also for O&M, business model cascade also illustrates that for each risk reduction tion factors • Stakeholder involvement/community participation and ownership • Knowledge and design guidelines measure, there is often a corresponding policy and • Governance, management, institutional arrangements management area, and sometimes more than one, • Force majeure/external events • Asset management that is relevant (indicated at the right side with Time – space Implementation time, exit strategy “Institutional Arrangements and Policies”). Coastal Flexibility and robustness (“future proof” in view of climate change) resilience strategies against storms, flooding, and erosion generally include measures from different Upscaling opportunities steps of the cascade, forming an integrated risk Applied Technical innovations innovations and reduction portfolio. Typical interventions in each know-how Nature-based solutions category are listed (see also Table 4.2). Capacity building and knowledge transfer Source: World Bank 2021. Bangladesh: 118 Enhancing Coastal Resilience in a Changing Climate The use of the cascade of coastal resilience strategies is instrumental in that it particular coastal resilience measure may vary across different communities provides insight into whether the full range of complementary interventions along the coast depending on the prevailing social, economic, ecological, and was used, and if not, what the reason for this could have been. As there is morphological systems. probably no single intervention that yields maximum resilience, it is important to understand what combinations of interventions can be used, how they The high-level assessment of the 36 projects underlined that the main complement each other, and what their combined effectiveness is. emphasis to reduce coastal risk in Bangladesh has been on three (out of the five) categories of the coastal resilience cascade: Coastal Protection (polder For the selected coastal risk reduction interventions, a classification scheme embankment rehabilitation and improvement programs), Impact Reduction (Table 4.2) was developed to identify all possible categories of interventions and outline the particular aspects of resilience they seek to enhance. It does Table 4.2: Coastal Risk Reduction Strategies not say that all measures are intrinsically resilient, as this very much depends on local conditions and the way the interventions are implemented. For Category Interventions instance, the Coastal Protection category includes a wide range of measures, Hazard • Restore sediment balance (e.g. reservoir flushing), from protective hard infrastructure to mangrove shelter belts. Under certain Reduction bypasses, tidal river management (TRM), etc. circumstances, an infrastructure solution may well be the right intervention to increase a community’s resilience by protecting its village, although it does Coastal • Hard measures (embankments, dikes, groynes, not improve the morphological resilience. Further, the perceived impact of a Protection revetments, slope protection, breakwaters, closure dams, etc.) Figure 4.2: Cascade of Coastal Resilience Strategies • Soft measures (mangroves, sand nourishment, dune restoration, etc.) • Hybrid solutions Land-Use • Setback lines, zoning, managed realignment Regulation • Building restrictions, protected areas • Policies and plans Impact • Early warning, evacuation plans, and infrastructure Reduction improvement (roads, telecom) • Cyclone shelters and refuge areas • Flood proofing of houses and infrastructure (power lines, water supply) • Community-based disaster risk management and awareness raising Residual Risk • Emergency response Reduction • Relief and recovery programs • Insurance • Livelihood improvement programs Source: World Bank 2021. Source: World Bank 2021. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 119 (cyclone shelters and EWS programs), and Residual Risk Reduction (livelihoods Table 4.3: Most Significant Projects Selected for In-Depth Assessment improvement, and awareness and preparedness programs). Much less attention Intervention Projects in Bangladesh has been given to the Hazard Reduction and Land-Use Regulation categories, but there are good reasons for this. For instance, reducing the storm surge Category: Coastal Protection hazard is very hard to do. With respect to coastal erosion, the situation is Flood prevention Blue Gold more nuanced: here one could imagine that the cause of coastal erosion (i.e. a Coastal Embankment Improvement Project Phase I sediment imbalance) can be mitigated through better sediment management. The underrepresentation of the Land-Use Regulation category can be partly Emergency 2007 Cyclone Recovery and Restoration explained by the fact that such interventions often do not materialize in a Project stand-alone investment project, but rather through legislation and regulation Measures to Integrating Ecosystems for Resilience of Coastal Island in by the government. Major steps have been taken in this area, illustrated by the combat coastal Times of Climate Change Coastal Zone Policy (CZP) (2005),14 the Coastal Zone Strategy (2006), and the erosion Sundarbans project recent BDP 2100,15 but the tools and institutional capacity for implementation Coastal Hydraulic and Morphological Study and Design are still very limited. of Protection Measures for Marine Drive Category: Impact Reduction It should be noted that many projects include interventions that do not focus solely on coastal protection; they are coupled with interventions that reduce the Cyclone EWS Multipurpose Disaster Shelter Project impact of hazards and residual risk should the protection fail. This corroborates and emergency Emergency 2007 Cyclone Recovery and Restoration shelters the ongoing trend to complement protection measures with other disaster Project reduction measures (Jongman 2018). Overall, projects seem to be less clear Improvement of Meteorological Radar System at Cox’s on arrangements for O&M, asset management, and exit strategies. A lack of Bazar and Khepupara O&M and asset management may hamper the long-term sustainability of Category: Land-Use Regulation interventions and should be an important point of attention. The lack of O&M Policy, planning, BDP 2100, CZP (2005) is complicated by the fact that many donor-aided projects do not provide and regulation funds for O&M, although some recent donor-funded projects in Bangladesh have started to include O&M funds in infrastructure projects (for example, the Source: World Bank 2021. Char Development and Settlement Projects III and IV). Recently, in order to coastal resilience strategy categories: (1) Coastal Protection; (2) Impact have a good knowledge repository of O&M processes, the Japan International Reduction; and (3) Land-Use Regulation. Interventions under Hazard Reduction Cooperation Agency (JICA) supported the preparation of the BWDB O&M were not included since the hazards themselves (that is, cyclones and storm Manual 2017.16 surges) cannot be reduced. The reason that interventions under Residual Risk Reduction were not selected is that these were not specifically linked to the Based on this high-level assessment, a subset of nine projects divided into four coast. Emergency responses, relief and recovery programs, insurance, and intervention categories (Sections 4.2 – 4.5 elaborate on these four intervention livelihoods improvement programs are more generic in nature. Although they categories in more detail) was selected for in-depth assessment, as outlined are still crucially important to increase the resilience of coastal communities, in Table 4.3. The selected interventions can be classified under three main the study of their success or failure factors are hardly linked to the specific coastal zone under consideration. Bangladesh: 120 Enhancing Coastal Resilience in a Changing Climate The analysis was conducted with certain limitations being recognized upfront: 4.2. Flood Prevention and Embankments (1) it was focused on specific interventions in a local area rather than the entire program or project as a whole; (2) the selection of interventions was In Bangladesh, the current polder concept to protect the coastal zone against based on an extensive literature review and stakeholder consultations, but flooding was introduced in the 1960s following several technical missions from they may not be fully representative of all past interventions implemented; (3) the United Nations in the 1950s. To provide context, the commencement of the both the quality and quantity of data were limited, since interventions were formal water management institutional structure and planning was an outcome considered from 1960 onward, and it was impossible to obtain all past records; of the successive floods of 1954, 1955, and 1956, which led the GoB to seek (4) it focused on larger, often donor-aided projects, because it was possible to international support through the United Nations. The mission published its obtain historical documents and information relatively easily for those; and (5) report in 1957, popularly known as the Krug Mission Report, leading to the there was a certain subjectivity in the evaluation as it arrived at the key factors formation of the East Pakistan Water and Power Development Authority in for success, importance, or relevance through the judgments of experts and 1959. Publication by the authority of the first 20-year Master Plan for Water other key stakeholders. Management in 1964 marked the beginning of water sector planning in what is now Bangladesh. The master plan was based on a strategy for flood control J. H. Laboyrie Swarna Kazi Example of coastal embankment and turfing (Polder 35/1). Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 121 and drainage improvement aimed at increasing agricultural production, grow over time. The polder concept has been taken forward through a series which is intrinsically linked to the beginning of the polder system, tidal flood of projects in Bangladesh that have led to the current system of 139 polders management, and food security for Bangladesh. across the coastal zone. At present, the 139 polders protect an estimated 1.2 million hectares of land (around 43 percent of the coastal zone), and more than The concept of using polders to prevent tidal flooding and (partly) protect against 8 million people depend on the land contained within the polders for their food storm surges can be found all over the world, including in Egypt, Morocco, security and livelihoods. China, Belgium, the Netherlands, the USA, and Argentina (UNEP 2017). In the Netherlands, for example, polders have been used since the 11th century and During implementation of the CEP, which started in 1961, approximately have resulted in prosperous and inhabitable zones for communities. Polders 4,000 kilometers of embankments were constructed to reshape the coast into typically consist of embankments, drainage and flushing systems, and water 108 polders, comprising about 1 million hectares of land. A series of projects management infrastructure (for example, sluice gates). followed to create new polders, and rehabilitate and improve existing polders, including the Early Implementation Project (1975), the Coastal Embankment The GoB’s decision to construct polders and complementary interventions was Rehabilitation Project (1995), and CEIP-I (2013) (see Figure 4.3). Within the aimed at protecting communities and key economic sectors (such as agriculture CEIP-I, the design of a number of polders was enhanced to protect against and fisheries) from hazards such as coastal inundation and saline water intrusion, present and future storm surges along with meeting the initial objective of thereby ensuring food security and enabling these key economic sectors to protecting the land from regular saline tidal flooding. Figure 4.3: Key Projects in the Coastal Zone Source: World Bank, original figure developed for this report. Bangladesh: 122 Enhancing Coastal Resilience in a Changing Climate S M Mehedi Hasan Improvements in agricultural production as a result of strengthened polder systems. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 123 S M Mehedi Hasan Improvements in agricultural production as a result of strengthened polder systems. Bangladesh: 124 Enhancing Coastal Resilience in a Changing Climate The impoldering has provided benefits for the communities living within the improvement of the embankments along the Baleshwar River with regards to polder areas by improving their livelihoods conditions because of increased the avoided damage from flooding. A detailed assessment (see details in Box agricultural production and less frequent floods and associated damages to 4.2) shows significant positive benefits, with avoided damages of approximately private and public assets and infrastructure. In the CEIP-I, a number of polder US$1 million per year, excluding the impacts of climate change, land value systems were rehabilitated and upgraded, with embankments designed to increases, and enhanced agricultural production. In addition, the improvements withstand a 25-year water level, and the polder drainage system to effectively to the embankment have directly resulted in 2,000 people being less affected drain a 10-year rainfall event with a five-day duration. Improved crop by coastal flooding on an annual basis, which is roughly 2 percent of the total productivity because of better drainage is an important contribution to total polder population (approximately 100,000). The reduction in risk is considerable benefits (39 percent) according to the CEIP-I economic analysis. The avoided compared to the investment costs. Construction of the embankment at the damage to assets such as roads and property is another significant benefit (in Baleshwar bank of Polder 35/1, with a lifespan until 2050, cost approximately total 47 percent). The economic analysis of the most recent polder rehabilitation BDT 480 million (US$5.5 million) (Bangladesh Water Development Board 2013). program under the CEIP-I has shown an overall benefit-cost ratio of 2.4 for the project (World Bank 2013). Other independent research confirms these Despite the overall success of the polders, several challenges have partially findings, underlining that there is a strong economic rationale for increasing hindered the past effectiveness of the polder system (see Table 4.4). First, a the current (relatively low) protection levels of the polder embankments in lack of proper O&M of both the embankments and the drainage systems is Bangladesh (Zaman and Mondal 2020). one of the major concerns, amplifying the deterioration rate of such structures and ultimately resulting in stability issues of the structures and inefficient water To highlight the benefits of polders in more detail, a reanalysis of the benefits management practices. In addition, rising sea levels and ongoing subsidence of the embankment improvement work during the CEIP-I for Polder 35/1 put an additional strain on the sustainable lifecycle of the polders. Only a was performed. In particular, the reanalysis focused on the effects of the limited number of embankments and drainage/flushing systems have been Table 4.4: Benefits and Challenges of Preserving the Polder System Item Benefits Challenges Agriculture Agricultural output has increased New problems, such as waterlogging, have emerged in certain polders. significantly. Water management Polders facilitate water Problems include siltation of peripheral channels, no proper maintenance of the drainage network management. because of a lack of working institutional arrangements and/or conflicts between different user groups, and waterlogging. These have become an impediment for the traditional cropping pattern with rice and shrimp farming. Flood protection In locations where embankments The significant wave attack and increased currents that have occurred over the years have caused are present, they have provided previously constructed embankments to suffer from erosion and breaches. These negative impacts significant protection from cyclone are amplified by the lack of O&M. storm surges. Source: World Bank, original table compiled for this report. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 125 Box 4.2: Reanalysis of the Effects of Embankment Improvement – A Case Study of Polder 35/1 The main objective of the reanalysis was to quantify the The goal of the risk analysis was to assess the risk reduction (that is, the reduction in annual reduction in risk as a result of the improvement of artificial direct impacts to exposed assets and people at Polder 35/1) resulting from the increase of levees (dikes, embankments) of low-lying coastal areas (polders) the dike crest level from a height of PWD 3.8 meters to a height of PWD 6.0 meters. in the Bangladesh coastal zone. The effect of the embankment improvements executed within the CEIP-I was considered for the analysis, with a specific case study of Polder 35/1. Figure 4.4: Map Showing the Spatial Distribution of the Maximum Flood Depth The following aspects were taken into account for computation of the crest level of embankments in the CEIP-I: • 25-year storm surge event • 25-year monsoonal flood level • Alternatives for freeboard depending on an overtopping limit of 5 liters per meter per second for several possible embankment slopes and roughness • An additional margin to allow for subsidence A flood inundation model was set up for Polder 35/1 to estimate the extent of flooding under the extreme surge levels and wave heights determined in the CEIP-I, which then delivered inputs for the risk modeling. The result of the inundation modeling was a spatial distribution of flood depth for each scenario modeled. Figure 4.4 shows the spatial distribution of the maximum flood depth (panel a) during the simulation with the old crest level of the embankment (Public Works Datum (PWD) 3.80 m) and hydrodynamic conditions corresponding to a 50-year return period (top right). Panel b) shows the forcing of surge levels on the three boundary points, panel c) shows the water level, and panel d) shows the water depth (with respect to bed level) on the two indicated points in the model domain. Source: World Bank 2021. Bangladesh: 126 Enhancing Coastal Resilience in a Changing Climate J. H. Laboyrie Example of coastal embankment slope protective works in Polder 35/1. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 127 S M Mehedi Hasan Example of coastal embankment, drainage sluice, canal, and agriculture in Polder 35/1. Bangladesh: 128 Enhancing Coastal Resilience in a Changing Climate renovated to cope with changes in the design conditions as a result of climate Box 4.3: Maintenance of Embankments Jointly by WMOs and Union change. Hence, significant additional investments are needed to incorporate Parishads climate change adaptations into the design of the other polders. Finally, river and coastal erosion due to waves and tidal flow currents has led to the Context: As originally conceived, responsibility for the O&M of the water management infrastructure in the polders was under the implementing agency— erosion of embankment slopes and bank protection works, indicating that the the BWDB. After its restructuring, there were not sufficient local-level staff to handle initially designed revetment and toe structures may have been underdesigned. the O&M work. Therefore, the GoB and BWDB realized that sustainable O&M of Therefore, the designs of these structural works need to be revisited to improve the infrastructure is not possible without the participation of local stakeholders. In their reliability and reduce the risk of structural failure. this context, the Ministry of Water Resources and the BWDB took the initiative to organize communities and build their capacity to take over responsibility for the For instance, alternative embankment designs, such as “smart embankments,” operation and routine maintenance of the infrastructure under different projects. have been proposed, which consist of improved bed protection, bank protection, The Blue Gold Program has an emphasis on sustainability through community and embankments in combination with the use of EEWS. The EEWS enables participation and constructive engagement of the local government institutions, monitoring of the erosion locally, which can help water managers maintain the especially the Union Parishads (UPs), in water management activities. As part of the embankments. program, the WMOs and UPs were briefed about their roles and responsibilities, and both agreed to work together and have already set an example in this regard. Recent projects, such as the CEIP-I and the Blue Gold Program,17 are taking initiatives to respond to the challenge of improving the O&M of the polder Description: WMG members and the UP jointly worked together to protect the infrastructure. Both projects have a strong focus on the involvement of local embankment at Polder 43/2A from river erosion. The WMG members contributed communities through participatory water management practices (see also Box their labor free of charge and the UP arranged the funding for the work. Upon 4.3). The 1999 Bangladesh National Water Policy18 formally recognized the role a request from the UP, villagers donated materials (bamboo, wood, rope etc.) to of all stakeholders in the management of water and mandated their participation use in protecting the embankment. in any scheme to promote sustainability to ensure the long-term integration of social and environmental conditions. Specifically, the GoB decreed Participatory In July 2014, the embankment at Balaikathi village, Polder-43/2B under the Water Management Rules in 2014, which resulted in the formation of water Awliapur UP was breached by river erosion because of high tides and flooding. management organizations (WMOs)19 having responsibilities within water The WMGs and UP jointly repaired the breached portion of the embankment resource projects. WMOs stimulate the engagement of local stakeholders following the same procedure mentioned above. (such as water users) in water management groups (WMGs), with the objective that the water users take over full responsibility for the operation and partial Strengths: responsibility for the maintenance of the water management infrastructure. • Joint initiative by the WMG and UP • Avoids dependence on the implementing agency As per the Participatory Water Management Rules, women must form 30 • Utilizes local resources percent of the WMO constituency and are to be given leadership training and encouragement by the project. Challenges: • Regular maintenance of water management infrastructure Another challenge is waterlogging in the polders, particularly in Satkhira, Jashore, • WMGs lack funds for regular maintenance of water management infrastructure Khulna, and Bagerhat districts, as a result of the interruption of sedimentation Source: Blue Gold 2015. inside the embankments combined with accelerated compaction, removal of Overall, despite the challenges identified (see Table 4.4), the rehabilitation and forest biomass, and a regionally increased tidal range. For context, the land strengthening of embankments have proven quite successful, safeguarding enclosed by the embankments in the southwest of Bangladesh has lost up to villages, household property, and agricultural land during cyclones and storm 1.5 meters in elevation relative to the mean height of the surrounding bodies surges. In addition, embankments have protected drinking water sources of water (Auerbach et al. 2015). Due to poor drainage, these polders face long- from salinity intrusion and improved transport connectivity through road standing and recurring flood problems during the rainy monsoon period. Plinth construction on top of embankments during normal times and emergencies. In rising and elevating the local habitats and physical infrastructures have been terms of effectiveness, use of proper morphodynamic studies and modeling is put forward as short-term measures (Awal 2014). Alternatively, a potential long- critical when planning and designing the infrastructure. However, O&M funds term solution to combat waterlogging to be considered is TRM. With TRM, the and sufficient monitoring of embankment stability remain key to sustainability. low-lying land is reconnected with the tidal channel through a breach in the embankment (for four to eight years), which prevents the rivers from silting up 4.3. Shoreline Stabilization and raises low-lying land by means of the sediment influx. Some studies have quantified the potential benefits of TRM on the sustainability of the polders The coastal zone of Bangladesh is a dynamic environment and certain areas (Adnan et al. 2020). It was found that TRM has the potential to raise land by 0.5 suffer from erosion, threatening communities and infrastructure (see Chapter to 2.0 meters and has co-benefits by reducing flood risk, improving conditions 2). Combating coastal erosion can be done in many ways and requires a site- for freshwater agriculture, and improving the ecology in the polder. However, specific approach that takes the local physical and ecological characteristics despite the promising outlook, a number of social and technical constraints into consideration (see Box 4.5). Hard solutions generally refer to structures have also been identified (see Box 4.4) that limit widespread adoption of the such as sea walls, coastal groynes, and granular or block revetments at the concept in the coastal zone. Furthermore, compensation is a large component bank or slope of the tidal riverbank or shoreline. Soft solutions, often classified of the total cost (65 to 80 percent), which makes it quite costly and difficult to as nature-based solutions or green infrastructure, use natural processes and implement. The use of TRM will be further studied as part of a large research materials for coastal protection, helping to maintain the natural landscape and program under the CEIP-I. coastal habitats. Examples include sand (or gravel) nourishments, vegetation/ mangrove planting, oyster breakwaters, and coral reef restoration. Hybrid Past polder projects in Bangladesh have faced several implementation solutions are combinations of hard and soft solutions, such as revetments challenges, resulting in longer implementation time and higher costs than covered with sand providing a natural habitat and attractive areas for recreation. originally anticipated. A key issue affecting the duration of implementation has Managed realignment (or managed retreat) is widely used in Bangladesh been timely acquisition of the land necessary for the construction works and if erosion cannot be stopped or is acceptable at a certain location. This is timely compensation for resettlement. Functional systems for land ownership implemented by removing structures and restoring natural intertidal habitats. and citizen registration as well as early communication with and involvement of A more proactive and well-recognized global practice is the establishment and the stakeholders are key ingredients to handling these aspects in a timely fashion enforcement of setback lines or zones. These are buffer zones to accommodate and are still challenges in Bangladesh. It is noted that delays or cost overruns in the ongoing erosion that have certain use restrictions, such as on housing, public works projects are not unique to Bangladesh but happen across the world industry, or infrastructure. (Durdyev and Hosseini 2019). More effective and proper planning in view of the project characteristics (such as land acquisition and resettlement payments) The most widely used approach to combat erosion in Bangladesh has been to and location characteristics (weather/climate conditions, remote sites) is one of build either temporary measures or hard engineering solutions. The presence the key focal points for improvement of future project performance. Bangladesh: 130 Enhancing Coastal Resilience in a Changing Climate Box 4.4: Tidal River Management TRM enables the natural movement of sediment-loaded tidal river water into Beel Khuksia in 2006 proved difficult, as less than 10 percent of the farmers an embanked low-lying area (a “beel”) during high tide. This leads to sediment who lost their land temporarily were given compensation at the time, although deposition in the beel as flow energy is significantly reduced. During low tide, the GoB committed to compensating other farmers at a later stage, and we the outgoing sediment-free water picks up river sediment, erodes the riverbed understand that this is still pending (Gain et al. 2017). Furthermore, TRM and increases the drainage capacity of tidal rivers. TRM requires a cut in the often raises conflicts among local stakeholders (such as between shrimp river embankment, or a link canal between the river and the beel, to allow for pond owners, farmers, and landless people). During TRM applications, some the daily transport of water and sediment into the low-lying area for a period communities rejected the cutting of embankments and favored embankment of at least several years (see Figure 4.5) During these years, the beel is flooded construction and increased flood prevention (Van Staveren, Warner, and Khan daily with water and sediment. TRM is capable of elevating land within the beel 2017) to avoid inundation-induced short-term losses in agricultural production between 0.2 meters (at the far end) and 2 meters (near the cutting point) and and aquaculture practices. increasing river flow as the tidal river deepens (by 9 to 12 meters) and widens Figure 4.5: Tidal River Management Conceptual Diagram (by 2 to 8 times the pre-TRM width) (Seijger et al. 2019). There are current and past formal and informal TRM projects in the Lower Bengal Delta in the southwest of Bangladesh. TRM was executed in the Kobadak River Basin and in the Khulna-Jashore Drainage Rehabilitation Projects. It is understood that TRM was introduced by the local people themselves during the latter project once it was clear that the project’s proposed solutions to overcome waterlogging were not satisfactory. However, the application of TRM is not without problems. In particular, the social complexity of the intervention poses hurdles in its implementation. TRM often creates conflict within local communities related to issues such as resettlement, affected economic activities, the effect on agriculture, and compensation for the (temporary) loss of land. For instance, compensation during the TRM in Source: Talchabhadel, Kawaike, and Nakagawa 2021. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 131 of assets (including cultural sites) in erosion-prone areas and the scarcity of land and even keep up with SLR by trapping sediment and dissipating wave energy are some of the key deciding factors for implementing measures to counteract through their complex aerial root system (Spalding et al. 2014). The Sundarbans erosion or use realignment as a last resort. Traditionally, temporary measures mangrove system in the southwest of the country provides enormous value in consist of geotubes and/or geobags to mitigate erosion. In terms of hard shoreline stabilization and acts as a large soft solution against coastal erosion. solutions, concrete block revetments, seawalls, and concrete block protection Bangladesh has a long-standing mangrove afforestation program dating back works have been used extensively in the coastal zone. However, even though to 1966, mainly concentrated on the islands in the eastern part of the delta and these structures can provide sufficient protection, they are generally expensive some coastal areas north of Chattogram. However, mangrove loss is continuing, and may have negative effects on the local sediment balance. In particular, with conversion to aquaculture and agriculture being the most common cause sediment losses at the toe or at the sides of the structure require additional (Thomas et al. 2017). The mangrove loss in the Sundarbans area has resulted measures and/or intensive maintenance over the design lifetime. in a large amount of coastal erosion in the area in recent years (Dasgupta et al. 2021), which has been recognized as a global erosion hotspot of a World Soft solutions to cope with coastal erosion have been applied in the coastal Heritage site (Sabour et al. 2020). In addition to mangroves, other species have zone as well, in particular the use of mangrove forests or other root species for been increasingly used for slope and foreshore stabilization, for instance Durba shoreline stabilization. Mangrove forests have the ability to stabilize shorelines, grass and Vetiver grass (see Box 4.6). Mahfuzul Hasan Bangladesh: Bhuiyan 132 Enhancing Coastal Resilience in a Changing Climate Reversing the ongoing trend of declining mangrove forests is critical for surge height by 4 to 17 centimeters and reduced the water flow velocity shoreline stabilization. Alongside the benefits of mangroves from a hazard substantially (Dasgupta et al. 2019). However, there is no evidence from the perspective, such as effective protection against storm surges, a healthy and past projects that Bangladesh is using other large-scale soft solutions, such wide mangrove forest has important co-benefits, as a natural habitat for fish as sediment nourishments to stabilize eroding coastlines (see examples in and other ecosystem services, a source of wood, and a carbon sequestration Box 4.5), although there are some small-scale nature-based pilot protection mechanism. Rahman, Jiang, and Irvine (2018) have shown that the economic initiatives in Kutubdia Island. value of mangroves in terms of storm protection equals US$12.60 per hectare per year, and in terms of coastal erosion, US$2.07 per hectare per year. In Managed realignment of existing polder embankments is also a well-known recent years, mangroves have been increasingly used to protect the outer tool in Bangladesh for erosion management. This solution, known as “retired slopes of the embankments and reduce the wave runup of coastal polders. By embankments,” in Bangladesh, covers the abandonment of the existing 2013, approximately 60 kilometers of embankments of sea-facing polders had embankment and the construction of a new embankment alignment at a certain mangrove forests in their foreshore areas (Dasgupta et al. 2019). A reanalysis setback distance from the river. This setback distance, which is typically 50 to of Cyclone Sidr suggests that the existence of the mangrove forest reduced 100 meters, functions as a buffer zone for the migrating river. The feasibility Dumping of cement concrete blocks. Chapter 4: S M Mehedi Hasan Empirical Evidence on Selected Coastal Resilience Interventions 133 CHAPTER 4 02 Box 4.5: Shoreline Stabilization Practices Around the World China China has an extensive coastline and numerous islands and is Figure 4.6: Coastal Erosion in Shandong, China severely hit by storms. Principal protection measures are coastal defenses such as seawalls (13,000 km of seawalls, most of them built after the 1980s) (Liu et al. 2019), breakwaters, and coastal shelter belts. It is estimated that over their lifetime, these seawalls could recoup their construction and maintenance costs threefold in preventing storm damage (Liu et al. 2019). They are a simple and easily implemented defensive tactic, blunting the force of floodwater and storm winds. However, that does not mean hard engineered defenses are without risk. Increased coastal erosion and other ecological damage can undo the benefit of seawalls and similar engineered structures. In the worst-case scenario, these structures trade one problem for another. And combined with SLR, significant erosion can be devastating to a coastline (see Figure 4.6). Although solutions, such as seawalls, did reinforce the coast, they also caused inconvenience during construction (Cai et al. 2009). Therefore, a new strategy of positive coastal protection has since been put forward where sand is positioned in front of the coast protection works and new types of groynes and offshore dikes and their combinations were built in different regions. The aim of this strategy is to dissipate waves and tidal energy in front of Source: Yin et al. 2018. the foreshore before they cause erosion, transform the previous integral protection into segmented protection, reduce financial costs, and beautify the coastal environment. Over the past 10 years, there has been a greater focus on a soft structural approach (such as beach nourishment and biological protection by mangrove planting) (Cai et al. 2009). Bangladesh: 134 Enhancing Coastal Resilience in a Changing Climate United States of America India In the United States, coastal erosion is responsible for roughly US$500 million India’s coastline suffers significantly from coastal erosion and makes use of per year in coastal property loss, including damage to structures and loss of both hard and soft solutions, although the latter more seldomly. For example, land. To mitigate coastal erosion, the federal government spends an average of there are seawall type structures in Puducherry, Uppada geotubes, Pentha US$150 million every year on beach nourishment and other shoreline erosion sea defense, and Digha-Sankarpur. Additionally, groynes are often used for control measures (U.S. Climate Resilience Toolkit 2021). coastline stabilization. An example of a detached breakwater using geotextiles is the shore protection at Kadalur village (Tamil Nadu). Soft solutions, such as In the past, protecting the coast often meant “hardening” the shoreline with beach nourishments, have been carried out in Puducherry, where about 0.2 structures such as seawalls, groynes, rip-rap, and levees. Over the years, as million cubic meters of sand was dredged from the mouth of the nearby port understanding of natural shoreline function has improved, many states have to replenish the shoreline. A cost-benefit analysis was not carried out before incorporated non-structural shoreline stabilization techniques as well. starting the project because it was a demonstration project, however the local inhabitants have reported an increase in tourism activities and fish catches after the installation of the submerged breakwater (which acts as an artificial reef that accumulates marine biomass) (World Bank 2021). Cliff erosion on the West Coast. (U.S. Climate Resilience Toolkit 2021) Source: U.S. Climate Resilience Toolkit 2021 Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 135 Ismail Ferdous Cement concrete block preparation. Bangladesh: 136 Enhancing Coastal Resilience in a Changing Climate S M Mehedi Hasan Slope protective works. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 137 J. H. Laboyrie Cement concrete blocks for shoreline stabilization west from Kuakata Sea Beach in Polder 48 in CEIP-I. J. H. Laboyrie J. H. Laboyrie Seawall constructed with geotubes and tetrapods at Marine Drive. Seawall constructed with geobags west from Kuakata Sea Beach in Polder 48. Bangladesh: 138 Enhancing Coastal Resilience in a Changing Climate of this solution depends on many factors, such as the availability of land, the coastal stretches or increase the scour near the toe of these structures, which presence of houses on the embankments, and the need for resettlement. can still result in instability problems. Hard solutions therefore require good Given the scarcity of land, as well as the social implications of this solution, it monitoring and O&M practices, which are often not adequately in place. For is typically a last resort if a temporary or hard engineering solution cannot be instance, geosynthetic tubes can deteriorate after several years due to harmful implemented. Although managed realignment is often used, Bangladesh does ultraviolet light and the energetic wave conditions along the coastline and are not have established setback lines for the entire coastal zone, with planning easily vandalized. Therefore, the design could be improved by overlaying them happening on a site-by-site basis. with other material, such as rock gabions. Ongoing monitoring is needed to detect if small maintenance work is necessary and to prevent early degradation The review of past projects on shoreline stabilization highlights that structural of these structures during their lifetime. The design guidelines of the typical solutions such as groynes, geotubes, and seawalls have been the main hard solutions in Bangladesh, such as slope and bank protection, can also be strategies used to control erosion, with some success. Although these hard improved, and should include morphodynamic studies and modeling for a solutions stop local erosion, they sometimes shift the problem to neighboring proper understanding of the system. View of the Sundarbans mangrove forest. S M Mehedi Hasan Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 139 Box 4.6: Slope and Foreshore Stabilization using Afforestation and Grass Turfing As part of the CEIP-I, afforestation programs are intended to provide Durba grass (Cynodon dactylon), a small creeping sward grass commonly found nature-based solutions to protect the polders from tidal flooding and storm on grazed land (Newman and Mukul 2021). Durba grass has been used in past surges. Social afforestation programs aimed at including communities in the polder reinforcement programs to protect the soil in the slope and crest of the construction and maintenance of foreshore and slope plantations have been embankments from erosion caused by rainfall, and wave and wind action. implemented in Bangladesh over the years. A key benefit of using grass is its cost, which can be five to eight times cheaper However, several questions remain in terms of best practices, such as the most than hard protection using brick or stone. However, environmental factors play suitable plant species for afforestation, their structural integrity in terms of a critical role in the suitability of different grass types. For instance, Vetiver grass embankment protection, ecosystem services they can provide, and the social has a salinity threshold of 8mS cm-1, which is slightly higher than Durba grass costs and benefits. Research has been undertaken to investigate these aspects, (6.9 mS cm-1) (Truong and Loch 2004). The benefits of Vetiver grass are that it particularly the species selection criteria within a bioengineering framework reinforces the shear strength of the rooted soil by a factor of eight compared and within a framework of sustainable environmental development and poverty to soil without grass, it grows quickly, it can endure a range of pH and salinity alleviation. The research suggests that species selection for afforestation levels, and it is tolerant of drought, flood, and submergence conditions (Islam programs should be based on (1) tolerance to local edaphoclimatic conditions, et al. 2013). On top of the structural integrity of Vetiver grass, farmers can use it (2) suitability for bioengineering purposes, (3) potential to assist in the as forage, mulching, and thatching material, while aromatic oil can be extracted conservation of specified aspects of biodiversity (birds, bats, small mammals, from the leaves and roots (Islam, Bhuiyan, and Hossain 2008). etc.), (4) ability to act as a framework species to speed up natural regeneration, (5) potential to improve livelihoods, and (6) potential to act as a nutritional The findings of the assessment indicate that Vetiver grass is superior to Durba supplement (Webb et al. 1984). grass in its ability to withstand high wind and wave action and heavy rainfall. Moreover, the salinity threshold is moderately high, making it suitable for most An assessment of suitability as a nature-based bioengineering approach for of the polders throughout the year. Bangladesh compared Vetiver grass (Vetiveria zizanoides), a grass native to tropical and subtropical India and known for its robustness and long life, to Bangladesh: 140 Enhancing Coastal Resilience in a Changing Climate Regarding soft solutions, the review shows that forest conservation and For example, the associated mortalities from cyclones have greatly declined restoration has proven to be a successful soft solution in stabilizing coastlines during the past 50 years (Haque et al. 2012). The two deadliest cyclones along the Bay of Bengal. Moreover, mangroves and other plant species provide occurred in 1970 (as per official estimates approximately 300,000 deaths) important co-benefits, and the combination of forests (such as mangroves and and 1991 (almost 140,000 deaths). The strong willingness to change this has Durba grass and Vetiver grass) with embankments appear to be a successful resulted in outstanding progress made over the past decades. For instance, the strategy for the protection of the outer slopes of the embankments under the most recent severe cyclone, in 2007 (Sidr), caused 4,234 deaths, a hundred- CEIP-I. The assessment also shows that other soft solutions, such as sediment fold reduction compared to the devastating 1970 cyclone (Ministry of Disaster nourishments, coral reefs, and oyster reefs, are promising but not yet widely Management and Relief 2010). The strategy to reduce these huge fatalities implemented in Bangladesh. One of the reasons for this may be that they are involved the development and implementation of an integrated cyclone not yet included in the current design guidelines applied in Bangladesh. In response system consisting of advanced EWS, cyclone shelters, and community addition, the wider acceptance of these types of solutions is not yet established, awareness and preparedness programs. To be effective, EWS needs the active as their effectiveness is highly dependent on the local conditions, exposure to involvement of the people and communities at risk. Community involvement extreme events, and knowledge of the morphodynamics of the system. Still, ensures that there is a good awareness and perception of the risk people face, pilot projects, such as the oyster breakwater project on Kutubdia Island, are messages and warnings are efficiently disseminated, and there is a constant ongoing and show promising results as soft solutions to stabilize shorelines state of preparedness that enables proactive evacuation to cyclone shelters. locally (see Box 4.7). Since 1972, a warning dissemination system has been in place in Bangladesh and The effectiveness of both hard and soft solutions also depends on community has been continuously improved over the past few decades. The Bangladesh involvement (see Table 4.5). During design, the involvement of local Meteorological Department has five meteorological radar stations—in Dhaka, communities is crucial to maximize the (co-) benefits and mitigate the negative Rangpur, Khepupara, Moulvibazar, and Cox’s Bazar—that transmit minute-by- impacts. More specifically, a good understanding of the rationale of the project minute weather updates. Since 1988, JICA has helped to improve the weather will likely result in community support, which can improve the design of the forecast service in Bangladesh through the establishment of meteorological intervention. Once implemented, local community involvement may also help radars, improvements in the weather analysis and forecasting system, and to identify maintenance needs early on, which is a crucial aspect of increasing capacity building. The Meteorological Department also receives information the lifetime and reliability of interventions. Although community involvement from the National Oceanic and Atmospheric Administration of the United has gained traction in the design and maintenance of water infrastructure, it States and from a Japanese satellite via the Bangladesh Space Research is less well established in the project implementation of erosion prevention and Remote Sensing Organization (Haque et al. 2012). The GoB is currently measures. implementing the Weather and Climate Services Regional Project, which seeks to further modernize the country’s climate information systems for forecasting 4.4. Cyclone Shelters, Early Warning, Evacuation Roads, and and strengthen service delivery in priority sectors and communities. Awareness Raising The construction of a large number of cyclone shelters has been another Based on the experience in Bangladesh, the amalgamation of cyclone shelters, cornerstone of this cyclone response system. One of the first major projects that EWS, access and evacuation roads, and timely dissemination of early warnings took up the construction of cyclone shelters was the Cyclone Protection and to communities of impending disasters has proven highly successful in Coastal Area Rehabilitation Project, which started in 1971 after the devastating minimizing fatalities and suffering, and the loss of critical assets. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 141 Md. Towhidul Islam PhD A CEIP-I foreshore plantation of Golpata mangroves Bangladesh: 142 Enhancing Coastal Resilience in a Changing Climate Box 4.7: Nature-Based Eco-Engineered Coastal Defenses Kutubdia, an island off the coast of southeast Bangladesh, is highly From a hydromorphological point of view, the main findings of the project are susceptible to erosion and flooding. The ECOengineered Coastal Defense (Tangelder et al. 2015): Integrated with Sustainable Aquatic Food Production in Bangladesh Project, • Oyster reefs can result in the accretion of sediment on the lee (the back) led by research institutes and a consultancy firm in the Netherlands and side of the reef, which can allow salt marshes and mangroves to develop Bangladesh, is being implemented on the island. It aims to provide an and expand. alternative approach for adaptation to coastal erosion and flooding. By • The accretion behind the reef can create a more extended foreshore, using the concept of eco-engineering, the project proposes an integrated which dampens wave energy for the primary defense (that is, the earthen approach, where oyster reefs reduce flow and dampen wave energy, thereby embankment). Wave reduction is, however, dependent on water levels (if trapping sediment and protecting against coastal erosion and flooding, there is a high water level, there is less wave reduction). while delivering a source of aquatic food to local communities (Chowdhury • Sediment accretion rates on the lee side can be up to 30 centimeters per et al. 2019). year, which is more than six times that observed in a similar pilot in the Netherlands. The project investigated the technical, social, and economic feasibility of eco-engineered coastal defenses through (1) ecological and socioeconomic A social cost-benefit analysis found that the combination of earthen field studies, (2) morphodynamics analysis, and (3) the construction and embankments with oyster reef structures and mangroves have considerable testing of pilot oyster reefs. benefits compared to the current situation (an embankment only) and other adaptation strategies analyzed (such as embankments and either mangroves Several key lessons were learned from the field experiments included in this or oysters) (Tangelder et al. 2015). These benefits could be higher if additional project (Tangelder et al. 2015): co-benefits (such as crab production, wood) are included in the evaluation. For instance, two to three families can generate livelihoods from selling mud crabs • Knowledge of the environmental conditions (salinity, pH, dissolved caught in a small oyster reef. oxygen) is essential to assessing the potential for oyster growth. • Sedimentation and smothering (sediment suffocation) were the main In short, artificial oyster reefs can prevent coastal erosion and grow fast enough threats to oysters during the monsoon period, in particular for structures in height to keep pace with SLR. Moreover, they can increase biodiversity, placed directly on the mudflats. provide shelter and substrate for fish and crabs, and create a source of food • The reef structure should be made of a more solid substrate with high for the local population. Where technically feasible, the combination of earthen vertical relief (to prevent smothering of the structure by mud). Bamboo embankments with oyster reef structures and mangroves may be considered reef structures could not withstand high-water dynamics during the since it has been shown to have relatively high benefits. monsoon period. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 143 Table 4.5: Benefits and Challenges of Measures to Combat Coastal Erosion Item Benefits Challenges Implementation of The current design procedure is Bank and slope protections follow design guidelines introduced in the 1980s and do not allow hard solutions straightforward and allows for quick for tailor-made solutions or account for the optimization of costs. These solutions also require implementation. These solutions have extensive maintenance and have potential side effects, such as shifting the erosion issue been widely used and there is extensive elsewhere. Additionally, they create beachfronts that are not easily accessible, thus dampening experience in Bangladesh with a variety of the potential for tourism. hard solutions. Implementation of They are flexible, climate proof, and can If not aligned with stakeholders to create proper incentives their effectiveness may be reduced. soft solutions often grow with rising sea levels. Mangroves They also require a proper understanding of the morphodynamics of the system. Design are a successful solution with proven co- guidelines and implementation experience for soft solutions (apart from mangroves) are still benefits. limited in Bangladesh; there is potential for further exploration and implementation. Source: World Bank, original table compiled for this report. Cyclone Bhola in 1970. Since the initiation of this project, many more cyclone (4) including in the design aspects related to gender (including for pregnant shelter projects have been implemented, hitting a peak in the mid 1990s (see women) and the specific needs of poor households and those with disabilities Figure 4.7). Following Cyclone Sidr (2007), new shelter programs such as the ensures not only higher usage but also better protection of key household ECRRP, the MDSP, and the Emergency Multi-Sector Rohingya Crisis Response assets. Water supply and sanitation facilities, rainwater harvesting options, and Project were initiated to rehabilitate and build new shelters. These programs solar panels and renewable energy options have been included in recently built included multiple innovations compared to the original design. At present, shelters and rehabilitated ones, which are beneficial both during disasters and approximately 5,000 multipurpose disaster shelters are located across the non-disaster times. Another good practice that has emerged is the formation coastal zone with a capacity of over 5 million people. of disaster management committees at the union level that ensure improved coordination between communities and government agencies, resulting in Several lessons have emerged from both the construction and usage of cyclone better maintenance of coastal resilience assets and mitigation of disaster- shelters: (1) constructing a shelter for multipurpose use, such as by a school or related impacts. These union disaster management committees consist of 36 community center, allows it to be optimally used and maintained; (2) involving members and have the mandate to act as the rural disaster management entity, the local community in the design and construction ensures sustainability in making sure that local communities are kept informed and are prepared to usage, ownership, and maintenance, this includes the provision of areas for make appropriate decisions during disaster situations. the community to bring their livestock; (3) investments in cyclone shelters, access roads, and EWS alone do not automatically lead to a reduction in the The effectiveness of the cyclone emergency response also critically depends vulnerability of communities if people are not aware of the EWS and emergency on the commitment of community volunteers to help out during large-scale actions. Therefore, along with the construction of structural measures, the evacuations. The Cyclone Preparedness Programme (BDRCS, n. d.), a joint focus has to be on increasing awareness and holding emergency drills; and program of the GoB and the Bangladesh Red Crescent Society, plays a central role Bangladesh: 144 Enhancing Coastal Resilience in a Changing Climate Figure 4.7: Cyclone Shelters in Bangladesh with Construction Date by Color 1995). Additionally, it is an example of a community-based program that takes advantage of indigenous knowledge for DRR (Habiba, Shaw, and Abedin 2013). During recent cyclone events, like Mora (May 30, 2017), Fani (May 3, 2019), Bulbul (November 9, 2019), and Amphan (May 21, 2020), many people took refuge in shelters. More specifically, a record 2.1 million people were evacuated to cyclone shelters across 14 districts prior to Cyclone Bulbul making landfall (November 2019) (International Federation of Red Cross and Red Crescent Societies 2020). The effectiveness of this cyclone response system of early warning, shelters, and awareness is also confirmed through a reanalysis of historical cyclones (see Box 4.8). The effectiveness of each of the components in this chain cannot be assessed, as it is their combination that makes the difference. Data from Bangladesh shows that after the mid-1990s, there was a reduction in reported fatalities from similar severe cyclones by an order of magnitude. The sharp reduction in fatalities between 1991 and 1997 is very likely the direct result of the efforts taken to improve the cyclone response system. Notwithstanding the great achievements of the cyclone response system Source: World Bank 2021. in Bangladesh, there are still some areas that require special attention. The safety and lifetime of the cyclone shelters could be improved by enhancing in this; it is recognized globally as a model program in the disaster management the maintenance of the building structures. Additionally, the routes linking the field. The program aims to minimize the loss of lives during cyclone disasters by residential areas to the shelters could be improved or restructured to promote developing and strengthening the disaster preparedness and response capacity a more efficient evacuation response time (ADB 2020). It should furthermore be of coastal communities. The program’s activities, executed by a few hundred ensured that there is an adequate power supply, together with adequate water staff and tens of thousands of volunteers, include the dissemination of cyclone and sanitation facilities, which currently are often not usable during emergency warning signals issued by the Bangladesh Meteorological Department through conditions (see Table 4.7). an extensive telecommunications network, providing and assisting in first aid, rescue, relief, and rehabilitation operations, and coordinating and building community capacity, disaster management, and development activities (Haque et al. 2012). Bangladesh’s cyclone response system, although not without its challenges, is viewed as a constantly evolving, but overall, very efficient mechanism to reduce losses, which has proven its success time and time again (Haque Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 145 Debashish Paul Shuvra Debashish Paul Shuvra Debashish Paul Bangladesh: Shuvra Debashish Paul Shuvra 146 Enhancing Coastal Resilience in a Changing Climate Box 4.8: Reanalysis of the Effectiveness of Cyclone Shelters Figure 4.8 shows a similar regession analysis as performed by Alam and In addition, two cyclonic storm events along the Chattogram coast with similar Dominey-Howes (2015), but subdivided into a pre- and post-construction physical characteristics were compared: one that occurred in 1991 and one in 1997 period, defined at 1995. The year 1995 was chosen because it was the peak (Table 4.6). The data show the characteristics and striking differences in the number year for the construction of cyclone shelters in Bangladesh. Although the of fatalities. Although the 1997 cyclone had a similar strength, the timing was correlation coefficient for the pre-construction fit is a bit low (r = 0.23), it different (low tide), it resulted in a disproportionately lower number of fatalities does suggest a significant reduction in the number of fatalities with one compared to the one in 1991. order of magnitude (Y-axis is logarithmic) for similar cyclone-induced storm surge levels in the post-construction period. It should be noted that the reduction in fatalities is an equation of not only the construction of new shelters, but also better warnings, better awareness, Figure 4.8: Reported Fatalities in Bangladesh and Total Storm Surge Height community preparedness, and infrastructure improvement, and it is therefore (tide + surge), 1974-2009 difficult to quantify the shelters’ contribution alone, although the two examples do indicate at least a strong correlation. Table 4.6: Meta-Information and Impact Statistics of Defined Cyclone Events in the Pre- and Post-Intervention Periods Type Cyclone Characteristics 1991 1997 Physical Date of landfall 29 April 1991 19 May 1997 Time of year Summer Summer Maximum wind speed (3-minute 225 km/h 232 km/h sustained) Category (Saffir-Simpson scale) 4 4 Storm surge (including tide) 6.7 m (high tide) 4.57 m (low tide) Fatalities 138,866 111 Impacts People injured 138,849 10,000 People affected 15,000,000 2,042,738 People homeless 300,000 1,000,000 Total damage US$1.78 billion - Number of cyclone shelters 450 1,900 constructed in Bangladesh Source: Data from Alam and Dominey-Howes 2015. Source: World Bank 2021, based on data from Alam and Dominey-Howes 2015. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 147 Table 4.7: Benefits and Challenges of the Effectiveness of Cyclone Shelters and Early Warning Systems Item Benefits Challenges Early warning and The current system has been continuously improved The current system relies heavily on external support. Moreover, emergency and emergency response and has proven to be effective. New technologies can evacuation rely on a large number of volunteers. Financing and partnerships easily fit into the current scheme. should be maintained to ensure the longevity of the intervention. Some barriers to evacuation still exist that should be addressed. Cyclone shelters Cyclone shelters have been shown to be effective The O&M of cyclone shelters can be improved. Moreover, the effectiveness of the in reducing loss of life. The multipurpose character shelters is driven by complementary measures in place, such as improvements in and other improvements made to recently built and access roads, places for livestock, and water and sanitation facilities. rehabilitated shelters are good examples of inclusive solutions with multiple co-benefits. Source: World Bank, original table compiled for this report. 4.5. Institutions and Policies for Coastal Zone Management Alongside international commitments, Bangladesh has a huge groundswell of The NPDM 2010-2015 (Ministry of Disaster Management and Relief 2010) and experimental learning from living with natural hazards for decades, which is the Disaster Management Act 201220 signaled a significant shift in disaster reflected in the various climate change and DRR policies adopted over the last management in Bangladesh from a relief-centric approach to one of proactive decade and a half, when Bangladesh began anticipatory adaptation planning, prevention, mitigation, and preparedness for all kinds of disasters. In 2015, starting with the development of the NAPA (Huq, Khan, and Brief 2017). Since Bangladesh adopted three international agreements—the Sendai Framework then, Bangladesh has recognized that adaptation to natural hazards and climate for Disaster Risk Reduction, the SDGs, and the Paris Agreement on Climate change impacts should be a national priority, with the gradual integration Change. These created an enormous impact on both the approach and of adaptation needs into national sustainable development and coastal practice of disaster management in the country, marking a strong shift towards zone planning (see Box 4.9). Within this context, Bangladesh has outlined proactive DRR. The Sendai Framework provides key directions on the inclusion its BCCSAP, which focuses on long-term adaptation planning and has also of climate change in DRR, a stronger focus on disaster risk management vis- integrated adaptation more broadly into development planning. For instance, à-vis disaster management, the concept of “building back better,” and the it includes social protection efforts so that the poorest and most vulnerable realization of measurable outcomes from DRR initiatives. The SDGs enjoin are protected from climate change and aims to better understand the linkages Bangladesh to pursue a path of inclusive development and poverty eradication between climate change and poverty in order to increase the resilience of the through the integration of the economic, social, and environmental dimensions poor. To mainstream the BCCSAP, the recent Second Perspective Plan 2021- of sustainable development. Improved coastal resilience is an essential element 2041 (General Economics Division, Bangladesh Planning Commission 2020) of Bangladesh’s Nationally Determined Contributions (NDCs) under the Paris emphasizes the importance of managing climate change and implementing Agreement, enhancing investment in sectors vulnerable to climate change, the BCCSAP in its vision for economic production over the next 20 years. The including coastal regions. 2012 Disaster Management Act focuses on protecting against disaster and Bangladesh: 148 Enhancing Coastal Resilience in a Changing Climate coping with residual risk. The emphasis is on rehabilitation (building back and Although Bangladesh has made significant strides in reducing disaster risk, building back stronger) by rebuilding infrastructure to present conditions or several barriers still exist that slow down the process of mainstreaming and better and bringing livelihoods back to normal. The 2013 National Sustainable implementing the country’s adaptation ambitions (Ayers et al. 2014). Areas for Development Strategy (General Economics Division, Bangladesh Planning improvement include the need to enhance coordination between the various Commission 2013) further aims to support economic growth while maintaining ministries involved in adaptation planning and strengthen synergies between social and environmental sustainability. DRR is seen as a cross-cutting element cross-ministerial plans and programs (Tye, Waslander, and Chaudhury, 2020). for long-term sustainable growth by finding synergies with DRR and climate In addition, despite the mandates to mainstream adaptation, only a few lead change adaptation. Such approaches have also been incorporated in the most ministries receive funding, which suggests that mainstreaming is being done recent NPDMs of 2016-2020 (Ministry of Disaster Management and Relief 2017) relatively selectively and ministries do not equally benefit from it (Rai, Huq, and 2021-2025 (Ministry of Disaster Management and Relief 2021), which also and Huq 2014). Also, increased community participation in decision-making, place a large emphasis on risks associated with urbanization. transfer of research and knowledge across ministries, and strengthened institutional capacity could benefit the DRR and climate adaptation process Hence, Bangladesh has recognized that climate change adaptation and the (Huq, Khan, and Brief 2017). broader development objectives, including achieving the SDGs, go hand in hand and should be addressed conjointly. Alongside this growing recognition In relation to coastal policies, the initiated CZP has not led to a measurable of the link between DRR, climate change adaptation, and development, effect to a more coordinated and sustainable development of the coastal zone. climate change adaptation has also been integrated into coastal zone disaster Reasons for this lack of progress include limited institutional capacity with preparedness plans and the 25-year water sector plan (Rai, Huq, and Huq 2014). regard to the development of coastal zone policies, the failure to assemble In parallel to the adaptation policies, two main policies/plans (partly) focus on a regular workforce, the rather land-centric view of the coastal zone, and the the coastal zone’s strategic planning and management: the CZP of 2005 and limited monitoring and follow-up plans of the policies outlined (Ahmad 2019). the BDP 2100 of 2018 (see Box 4.9). Proper communication between the agencies involved in drafting such follow- up plans is essential for the successful implementation of coastal strategies. The GoB has thus consistently emphasized the importance of adapting to climate change in combination with DRR policies. To translate this desire into The recent BDP 2100 has built upon the CZP and proposes a large number practice, it has established climate change steering committees to incorporate of concrete coastal projects that address the current coastal challenges, such climate adaptation into national-level planning. In addition, the GoB has as local water management and char development, while having a long-term facilitated access to several climate-relevant project funds (Bangladesh Climate planning outlook. Under the BDP 2100, a portfolio of interventions, worth Change Resilience Fund and the National Disaster Management Fund) and approximately US$11 billion, is planned. Implementation of this portfolio of mandated that any project submitted to the Planning Commission has to be interventions has a high expected success rate, since the BDP 2100 is closely checked for alignment with climate change issues (Pervin 2013). In parallel, linked to the Planning Commission and is taking into consideration the the BWDB acts as the major governing body for the overall development successive Five-Year Plans of the commission (Seijger et al. 2017). The BDP and management of water resources and is also responsible for the design 2100 is an encouraging development that can contribute to coastal resilience of coastal interventions, with the Chief Engineer of Design the main decision- but requires the addressing of institutional limitations in coastal planning to be maker in the design process. successful. Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 149 Box 4.9: Plans and Policies for Disaster Risk Reduction and Climate Adaptation Planning The Coastal Zone Policy 2005 was initiated by the GoB because many aspects In addition, the National Plan for Disaster Management 2021-2025, a successor of the coastal zone’s socioeconomic development were lagging behind, the of the previous NPDMs of 2010-2015 and 2016-2020, places importance on initiatives to cope with different disasters were lacking, the environment was emerging risks linked to urbanization and climate change, and the necessity of gradually deteriorating, and lastly, because the coastal zone has the potential DRR for sustainable development, and is flexible and adaptive in recognition to strongly contribute to national development. Adoption of the CZP by the of the changing nature of risks in Bangladesh. In view of the special long- GoB was a significant step towards implementing the Integrated Coastal Zone term challenges for development outcomes presented by climate change and Management Plan, which would provide general guidance on the management natural hazards, the GoB formulated the long-term Bangladesh Delta Plan 2100 and development of the coastal zone so that it is done in a manner that allows (approved in September 2018) to move Bangladesh forward to the end of the those living in the coastal zone to pursue their lives and livelihoods within a 21st century. The GoB is firmly committed to the implementation of national- secure and conducive environment. The CZP suggested measures for protection level strategic plans such as the Five-Year Plans and the Perspective Plans, and of the coastline from soil erosion, floods, and storm surges, which were later meeting the targets under the SDGs. adopted by the NAPA. Finally, Bangladesh introduced the Standing Orders on Disaster (SOD) in 1997, Recognizing that climate impacts were undercutting hard-won human which were then revised in 1999, 2010, and most recently in 2019. The SOD is an development gains, Bangladesh took strides on adaptation planning, by, among important part of the disaster regulatory framework in Bangladesh (UNDP 2020). others, implementing the NAPA 2005, updated in 2009. The basic approach in The SOD was prepared to clarify the duties and responsibilities of ministries, preparing the NAPA was to develop it in consideration of the SDGs and the divisions, agencies, organizations, committees, public representatives, and country’s recognition of the necessity of addressing environmental and natural citizens to cope with natural disasters. The most recent update in 2019 focused resource management issues with the participation of stakeholders bargaining on linking the SOD with five frameworks—the Sendai Framework, the SDGs, over resource use, allocation, and distribution. the Paris Agreement on Climate Change, the Five-Year Development Plan of Bangladesh, and the BDP 2100. The revision of the SOD constitutes a disaster The GoB’s vision to eradicate poverty and achieve economic and social wellbeing preparedness activity as well as a DRR activity, as it will facilitate coordination for all people was enhanced through a pro-poor Bangladesh Climate Change of an emergency response and consequently, prevent the further loss of lives Strategy and Action Plan 2009, which prioritizes adaptation and DRR, and also following a major disaster. addresses low carbon development, mitigation, technology transfer, and the mobilization and international provision of adequate finance. It outlines the first set of activities that are to be undertaken in line with the needs of communities and the overall development program of Bangladesh. Bangladesh: 150 Enhancing Coastal Resilience in a Changing Climate 4.6. Lessons Learned from the Assessment of Past Projects of temporary or hard solutions, which have been only partially successful. There is good evidence on the effectiveness of nature-based solutions with The assessment of past interventions in Bangladesh presented in this chapter mangrove restoration and better sediment management, which could be reveals various lessons learned that should be considered in the development considered more often in the future as a feasible alternative when supported of future investment programs. Six key issues identified are summarized below: by evidence of global best practices and improved understanding of the morphological dynamics. • A stronger link is needed between the strategy/policy for the coastal zone and the implemented interventions. The recent BDP 2100 has built upon • Waterlogging in polders is a major issue in the southwest of Bangladesh. the CZP, proposing a large number of concrete coastal projects but also Water management in the polders suffers from impeded drainage through recommendations to develop a more detailed strategy for the various limited maintenance, and declining gradients between sinking land coastal subzones (Southwest, South, Meghna Estuary, Southeast) to justify (because of subsidence and sediment cut-off) and rising water levels in the and prioritize the investments to reduce risk in the coastal zone (such as rivers from siltation and SLR. TRM applications have demonstrated their new embankment programs). usefulness to increase sediment deposition and polder levels. However, the implementation of TRM in polders is not without hurdles because of • Project implementation requires more realistic planning but also more resettlement and compensation issues. and earlier communication with local stakeholders. Large-scale structural interventions in polders (e.g. raising and widening embankments but also • A better analytical knowledge base can help support decision-making. The TRM) require land, and resettlement or compensation of the population. review of the interventions underlined that there is room for improvement Past programs have shown that this entails a very intensive and time- in the planning, design, and implementation of coastal interventions and consuming process with the communities in the polders, resulting in the use of state-of-the-art information tools and practices. Specifically, a significant delays during implementation of these programs. This is a comprehensive framework and application of a more risk-based approach global challenge for public infrastructure works, and knowledge exchange to guide the planning and design of investments using the vast amount with international partners to share best practices in this respect can also of data on the Bangladesh coast can be further utilized. For example, the support improvement of the implementation process. risk analyses of the historical interventions can be expanded in terms of determining the full range of economic benefits beyond only direct • The O&M of all infrastructure assets providing water management and damage as one dividend (that is, the Triple Dividend approach (see flood and erosion protection services needs much more attention. O&M Section 7.8 for further details)), and the planning and design of coastal of the investments (whether they be embankments, khals, drainage interventions such as embankments could benefit from better knowledge structures, cyclone shelters, EWS) is essential to make these investments of the morphodynamics.21 Embedding this knowledge into the planning sustainable. Although various programs have been and are working and design process is critical for sustainable embankments and any other towards a better O&M organization, there are shortcomings regarding infrastructure investments nearshore and along the tidal riverbanks. roles and responsibilities, capacity, ownership, and funding. The next chapters address some of these lessons learned in that they provide • Tidal riverbank and coastal erosion are becoming an increasing risk in the further analytical work on two specific aspects: the added value of a more risk- coastal zone due to the increasing number of people and assets located in based approach in the entire cycle of planning, design, and O&M of coastal erosion-prone areas. Erosion has been combatted predominantly by means interventions (Chapter 5), and the opportunities for hybrid and soft solutions to deal with coastal protection and shoreline stabilization (Chapter 6). Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 151 4.7. Notes 13. In this chapter, we make a distinction between structural and non-structural solutions and interventions. Structural interventions are positioned in the physical space; examples are embankments, sluices, afforestation. Examples of non-structural interventions are raising awareness and EWS. Within structural solutions, a distinction is made between soft and hard structures. Hard structures are largely made of concrete or rock, like bank protections and drainage sluices, whereas soft structures are made of materials or structures available in nature like mangroves, sand nourishment, and earthen embankments. 14. http://nda.erd.gov.bd/files/1/Publications/Sectoral%20Policies%20and%20Plans/Costal-Zone-Policy-2005.pdf. 15. https://oldweb.lged.gov.bd/UploadedDocument/UnitPublication/1/756/BDP%202100%20Abridged%20Version%20English.pdf. 16. https://openjicareport.jica.go.jp/pdf/12292587_02.pdf. 17. The Blue Gold Program is a donor-funded project aimed at empowering community organizations to sustainably manage water resources. For more information, see bluegoldbd.org. 18. Available at http://nda.erd.gov.bd/files/1/Publications/Sectoral%20Policies%20and%20Plans/National%20Water%20Policy%201999.pdf 19. 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Mondal. 2020. “Risk-Based Determination of Polder Height against Storm Surge Hazard in the South- West Coastal Area of Bangladesh.” Progress in Disaster Science 8 100131. doi: 10.1016/j.pdisas.2020.100131. Bangladesh: 154 Enhancing Coastal Resilience in a Changing Climate Tapash Paul Chapter 4: Empirical Evidence on Selected Coastal Resilience Interventions 155 APPLYING A RISK-BASED APPROACH TO COASTAL RESILIENCE 5.1. Risk Management Frameworks 5.2. Tolerable Risk Guidelines 5.3. Risk-Informed Planning 5.4. Risk-Based Design 5.5. Operation and Maintenance 5.6. Notes 5.7. References 156 Bangladesh: Enhancing Coastal Resilience in a Changing Climate 5 S M Mehedi Hasan CHAPTER 5: APPLYING A RISK-BASED APPROACH TO COASTAL RESILIENCE Identifying and managing the risk from natural hazards is one of the key objectives the resulting consequences of harmful events. The consequences may include, of adaptive delta management (ADM). Catastrophic events such as Cyclone among others, loss of life, economic loss, welfare impacts, and environmental Bhola (1970), Cyclone Gorky (1991), and the more recent cyclones Sidr (2007) damage. These risk components include many uncertainties not only because and Aila (2009) can wreak significant havoc and undo years of development of the limited ability to predict extreme weather events and impacts, but also progress. Reducing the risk from natural hazards is therefore vital to achieving because of uncertain future developments and changes (e.g. socioeconomic development goals. Risk is the product of hazard, exposure, and vulnerability. changes or climate change). Hence, identifying and managing risk from natural Together, these three components determine the probability of occurrence and hazards must take these uncertainties into consideration. Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 157 Risk management frameworks are used in various countries and industries sections discuss how risk could be used to aid, and tie together, three activities to inform decisions about public safety and mitigate risk. These frameworks that are essential to achieving coastal resilience: planning (Section 5.3), design emerged in high-hazard industries such as aviation, chemical manufacturing, (Section 5.4), and O&M (Section 5.5). In each of these three sections, the risk and nuclear power generation (Ball and Floyd 1998). Developments were management approach is applied to a specific polder to illustrate its potential. strongly driven by high-profile disasters such as the Seveso industrial disaster (1976), the Bhopal chemical disaster (1984), the Chernobyl nuclear disaster 5.1. Risk Management Frameworks (1986), and the Piper Alpha disaster (1988), which laid bare the limitations of previously adopted management practices. Risk management frameworks are Successful risk management requires people to work in coordination. now used in countries such as the Netherlands, Vietnam, and the United States Establishing strategic priorities, developing action plans, prioritizing to manage various types of risk. Within the scope of DRR, risk management interventions, designing measures, and implementing O&M schemes are frameworks are particularly well established when looking at flood risk, allowing closely related activities. Yet they are typically carried out by different people these countries to control the risk of flooding in a more effective and cost- who work for different organizations. In Bangladesh, for instance, coastal efficient way than they could using more traditional approaches. resilience interventions involve different ministries, such as the Ministry of Finance, the Ministry of Planning, the Ministry of Water Resources, the Ministry Bangladesh could benefit from a more intentional and structured application of Local Government, Rural Development, and Cooperatives, and the Ministry of a risk management framework for the planning, design, and maintenance of Environment, Forest, and Climate Change; their respective agencies, such as of coastal resilience interventions. With over US$10 billion invested in coastal the BWDB, the LGED, the Department of Environment, the Bangladesh Forest resilience (World Bank 2013) since Independence, and significant additional Department; and international development partners. It is important that their investment needed over the next several decades, implementing a risk efforts are closely aligned to ensure that goals are met effectively and efficiently management framework could further improve the effectiveness and efficiency given resource constraints. If agencies use a different rationale for decision- of interventions by better aligning the actions of different organizations. It making (such as life safety considerations, cost-benefit analyses) without a joint could also help the country to manage the risk related to natural hazards (such evaluation framework, the end result is unlikely to be as effective. as storm surges, cyclone winds, erosion) more proactively, which is likely to become increasingly important in light of increased economic development A risk management framework is a scheme that directs and controls and climate change. organizations with regard to risk. The key components of flood risk management frameworks are risk analysis, risk evaluation, and risk control (Figure 5.1) (US This chapter shows how a risk management framework could directly support FEMA 2015). Risk analysis involves risk identification and risk estimation, which efforts to improve coastal resilience. It does so by showcasing the international is the estimation of the probabilities and consequences of the hazard on the state of practice, providing examples from other countries, and discussing one hand, and exposure and vulnerability on the other. Risk evaluation is the their relevance to Bangladesh. Herein, the focus is on the risk of coastal and process of deciding on the tolerability of risk and the need for interventions. riverine flooding, but a risk management framework could also be applied to Together, risk analysis and risk evaluation are commonly referred to as risk other risks, either natural or human-induced. Section 5.1 gives an overview assessment (US FEMA 2015). Risk control involves the implementation of risk of the key components of flood risk management frameworks. Section 5.2 management actions. It includes planning, design, execution, monitoring, and discusses tolerable risk and decision-making guidelines that are essential to O&M. An example from the United States of how this is applied in practice is ensure consistency throughout the risk management process. The last three shown in Figure 5.2. Bangladesh: 158 Enhancing Coastal Resilience in a Changing Climate Risk communication, while not portrayed separately in Figure 5.1, is an activity Figure 5.2: Dam Safety Risk Management Framework that plays a critical role throughout the entire risk management process. It involves two-way communication between agencies and stakeholders to better understand the risk and to ensure appropriate actions are taken. The power of risk communication in Bangladesh is clearly demonstrated by the massive life-saving evacuations that happen as a result of the developed cyclone EWS. Figure 5.1: Schematic Overview of the Key Components of a Flood Risk Management Framework Source: US FEMA 2015. The risk management process is a cyclical process with repetitive steps for continuous improvement and learning. Since Bangladesh’s coastal zone is far from static, achieving coastal resilience will require constant adaptation to changing conditions. These dynamics have different timescales. For instance, newly constructed embankments may suffer from bank erosion, warranting timely intervention to avoid collapse. Economic development, population growth, and changes in land use may gradually increase exposure and vulnerability, creating a need for better protection. Furthermore, climate change may increase the flood hazard and aggravate issues such as waterlogging and salinity intrusion, creating a need for additional or different types of Source: US FEMA 2015. interventions. These examples clearly illustrate that coastal resilience cannot be achieved through one-time interventions, and show why continuous O&M, procedures that ensure a continuous, balanced, and internally consistent risk reassessment, and adaptation are indispensable. Box 5.1 describes how these management process. It does not require merging projects into a single long- are integrated into a levee safety program in the United States. running project of uncontrollable size or concentrating powers in the hands of a single authority. For instance, in the Netherlands, flood protection is the shared Implementing a risk management framework relies on the establishment of responsibility of the country’s 21 Water Boards and the national government. a clear institutional structure, with a set of formal and informal norms and The Dutch Water Act (the main legal framework) plays an important role in Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 159 Box 5.1: The Continuous USACE Levee Safety Program Management Process In 2006, in the wake of the flooding of New Orleans caused by Hurricane Figure 5.3: USACE Levee Safety Portfolio Risk Management Process Katrina, the U.S. Army Corps of Engineers (USACE) established the Levee Safety Program. The program’s mission is to assess, manage, and communicate the risk of flooding from embankment failure. The USACE Levee Safety Program follows a risk-informed management process for managing a portfolio of embankments with a total length of approximately 40,000 kilometers based on the most recent information (USACE 2021). Two hurricane-prone states with large embankment systems are Louisiana and Texas, which have about 17% of the total portfolio in their territories (USACE, n.d.). In terms of sheer scale, this is comparable to the roughly 6,000 kilometers of embankments in Bangladesh’s coastal zone. The USACE portfolio management process is a continuous, cyclical process, as shown in Figure 5.3. It includes the following two types of activities: • Routine risk management (outer loop): These include inspections, screening, classification, O&M, and emergency response planning that are an essential part of an effective levee safety risk management approach. Screening is used to inform the classification process, which leads to the prioritization of further risk management actions. • Non-routine risk management (inner loop): These include identification of levee safety issues that require further investigation, risk assessments, identification of options for managing inundation risks, prioritization of activities, and implementation of interim and permanent risk management measures. The routing of the levee systems through the portfolio management process is determined by the Levee Safety Action Classification (LSAC). When levees require further evaluation, a Levee Safety Risk Management Study is carried out to support decision-making on rehabilitation. Once measures have been Source: USACE 2011. implemented, the levee system is reassessed and the LSAC revised. If no further issues remain, the levee system will enter the outer loop of routine levee safety activities. This process ensures that risks are managed effectively, efficiently, and continuously. Bangladesh: 160 Enhancing Coastal Resilience in a Changing Climate combining their efforts in a continuous risk management process (Box 5.2). Box 5.2: Public Law as the Basis for Continuous Flood Risk Management Similar to the Bangladesh Water Act, the Dutch Water Act lays out the duties in the Netherlands and responsibilities for water management. However, the Dutch Water Act goes further; it provides a legal basis for sustainable funding, which is of paramount The Netherlands is protected from large-scale flooding by a system of primary importance, and prescribes a process of continuous monitoring, inspections, flood defenses. These dikes, dunes, dams, and structures must comply with maintenance, (re)assessment, and restoration. the flood protection standards specified in the 2009 Dutch Water Act. These standards play a key role in a cyclical risk management process that aims to Embedding DRR projects in Bangladesh in a more intentional and structured lower the risk of flooding to the politically established levels of ambition for 2050. Similar to the 2013 Bangladesh Water Act, the Dutch Water Act lays out the risk management framework could further enhance their effectiveness. The duties and responsibilities of the agencies responsible for water management in project evaluations from Chapter 4 show that past DRR projects in Bangladesh the Netherlands. The 21 Water Boards and the Rijkswaterstaat (an agency under have been highly successful in reducing the risks from natural hazards in the Ministry of Infrastructure and Water Management) are the key players. The Bangladesh’s coastal zone. However, the evaluations also show that often Dutch Water Act has three unique elements: projects are initiated in response to disasters, not as part of a continuous risk management process. For instance, the ECRRP was created in response to the • It includes financial provisions to ensure the availability of continuous destruction caused by Cyclone Sidr in 2007. While disaster response is essential funding for flood risk management actions. For instance, the Dutch Water to facilitate recovery, a more proactive, forward-looking approach that exploits Act requires the establishment of a Delta Fund, administered by the Minister synergies between projects, ensures adequate O&M, and allows for constant of Infrastructure and Public Works, to fund water management measures readjustment is vital to taking the next step in increasing the resilience of the and related research activities. It also provides the legal basis for the National coast. This way of thinking is also reflected in the BDP 2100 and the closely Flood Protection Programme, from which 90 percent of the costs of the aligned Second Perspective Plan of Bangladesh 2021-2041. The implementation restoration projects carried out by regional Water Boards are subsidized. of a risk management framework could greatly help to realize the ambitions of However, the costs of O&M are borne by the Water Boards themselves. these strategic plans. • It specifies that Water Boards have a statutory duty of care for the primary The commitment of the GoB to initiate a more continuous, forward-looking flood defenses they own and operate. The law thus obliges them to implement risk management process is illustrated by projects such as the World Bank- adequate O&M schemes, which is verified by an independent inspectorate. funded Coastal Embankment Improvement Project Phase 1. The project’s long To avoid a shift from O&M to restoration, the Water Act sets out eligibility term end objective is to increase the resilience of the coastal population to conditions that effectively mean that restoration related to inadequate O&M tidal flooding, storm surges, and natural disasters in a changing climate, while is not eligible for subsidy from the National Flood Protection Programme. supporting the development of polder livelihoods by upgrading the entire embankment system. With an estimated 6,000 kilometers of embankments for • It obliges the Water Boards and the Rijkswaterstaat to assess the safety of 139 polders, this is a huge undertaking (World Bank 2013). Hence, a multiphase the country’s primary flood defenses once every 12 years. If a flood defense approach has been proposed, with each phase building on the next. CEIP-I fails to pass a statutory assessment, measures must be taken. In addition to is the first phase of this potential long-term endeavor. It focuses on a group this 12-year reassessment cycle, the Water Boards and the Rijkswaterstaat carry out inspections, maintenance, and repairs. This also includes licensing of 10 prioritized polders where risk management actions are considered most and enforcement to avoid encroachments, such as buildings and vegetation, urgent. While O&M is largely outside the scope of CEIP-I, the project is piloting on flood defenses that could affect their performance. engaging local communities in minor maintenance works (see Chapter 4). The inclusion of prioritized polders based on urgency and O&M into the project are consequence of contact with a hazard, such as an explosion, toxic chemical, essential elements towards a more forward-looking risk management process or floodwater. Guidelines for evaluating individual risk are widely used for and should be further enhanced in its next phases. identifying and avoiding gross disproportionalities within populations at risk. Individual risk guidelines for flood risk management are typically 5.2. Tolerable Risk Guidelines 10-4 or 10-5 per year in developed countries such as the United States, the Netherlands, and Australia. For instance, a guideline of 10-4 per year has Tolerable risk guidelines are decision-making aids that can greatly improve the been adopted for existing flood-control and hydropower dams by the consistency of risk management decisions. Such guidelines make explicit when USACE (USACE 2014), the United States Bureau of Reclamation (Bureau risks are adequately controlled, when action is considered urgent, and when it of Reclamation 2011), the Australian National Committee on Large Dams is not. They help maximize efficiency by ensuring that decisions are all geared (ANCOLD 2003), the New South Wales Dam Safety Committee (New South towards achieving the same objectives. Tolerable risk guidelines have proven Wales Government Dams Safety Committee 2006), and the Canadian Dam to be useful in explaining risk mitigation strategies and actions to stakeholders Association (Canadian Dam Association 2007). For new dams and major and policymakers (Hall et al. 2012). Moreover, they allow the identification of augmentations, these organizations have adopted a stricter guideline of alternative strategies for managing risk in relation to tolerable risk guidelines. 10-5 per year. Finally, the Dutch have adopted a limit of 10-5 per year for On its own, CEIP-I already involves a multitude of risk management decisions, evaluating the local individual risk of flooding. ranging from its overall strategy of embankment rehabilitation, the prioritization of polders, the selection of restoration works within the polders, the choice • Societal risk concerns the risk related to the potential occurrence of of a 25-year design standard for river embankments, to the detailed design an event that may cause societal concern and a loss of confidence decisions and standards. Although the elements of a risk-based approach are in regulatory agencies and government (HSE 2001). Such an event in place, aligning such decisions is currently challenging, since explicit decision- is widely understood to be an event that leads to substantial loss of life. making guidelines are not yet established. Societal risk is therefore typically measured in terms of probabilities and the potential numbers of fatalities. It is often portrayed on charts with Tolerable risk guidelines have been developed in various countries for probabilities plotted along one axis and the number of fatalities along supporting flood risk management decisions. These international examples the other. Different types of societal risk charts and guidelines are used could serve as inspiration for the development of tolerable risk guidelines worldwide, reflecting subtle differences in both the meaning of societal risk that are tailored to Bangladesh (see Box 5.3 for one example). Although the and the factors that determine its tolerability (Jonkman, van Gelder, and tolerable risk guidelines developed by the agencies in different countries vary, Vrijling 2003). Exceedance probability curves of the number of fatalities they show many similarities. They typically involve quantitative evaluation (so-called F-N curves) are most common, which include reference lines for criteria or guidelines, to be used against the backdrop of general guiding evaluating the acceptable level of societal risk. These are used in various principles, such as the principle that risks ought to be reduced to levels that countries for evaluating third party risks from major industrial hazards, are “as low as reasonably practicable” (ALARP). These quantitative guidelines and used in Australia, the Netherlands, the United States, and Vietnam typically focus on individual risk, societal risk, and economic risk. to portray and evaluate societal risks from flooding (Ball and Floyd 1998; Jonkman, Vrijling, and Vrouwenvelder 2008; US FEMA 2015) (Figure 5.4). • Individual risk concerns the exposure of a person to a hazard. It is Similar guidelines could be developed for evaluating the risk of flooding in typically expressed as the probability that a person will die as a direct polders in Bangladesh. Bangladesh: 162 Enhancing Coastal Resilience in a Changing Climate Box 5.3: Risk-Based Flood Protection Standards for Coastal Embankments in Vietnam The Technical Standards in Sea Dike Design (Vietnam Ministry of Agriculture and Rural Development 2010) provide guidance for the design and rehabilitation of various types of coastal embankments and other types of coastal defenses. Sea dikes are classified into five grades (Grades I to V). The grade determines the safety standard of the protected area, which in turn depends on two aspects: the size of the protected area and the size of the population. The larger the protected area and the higher the number of people, the higher the safety standard (see Table 5.1 below). The highest safety standard (Grade I) is a return period of 150 years, while the lowest is between 10 and 30 years (Grade V). Table 5.1: Vietnamese Standards for Sea Dikes Characteristics of the Protected Area Safety Standards (return period: years) Developed industrial urban area: 150 • Protected area > 100,000 ha • Population > 200,000 people Rural areas having developed industry and agriculture: 100 • Protected area: 50,000 – 100,000 ha • Population: 100,000 – 200,000 people Developed rural and agricultural area 50 • Protected area: 10,000 – 50,000 ha • Population: 50,000 – 100,000 people Medium-developed rural and agricultural area 30 • Protected area: 5,000 – 10,000 ha • Population: 10,000 – 50,000 people Underdeveloped rural and agricultural area 10 < Safety Standard < 30 • Protected area: < 5,000 ha • Population: < 10,000 people Source: Vietnam Ministry of Agriculture and Rural Development 2010. Notes: • Developed industrial and agricultural areas are determined on the basis of the percentage of economic structures in the protected area. If the industrial rate is greater, then it is a developed industrial area and vice versa. • When using Table 5.1, first the protected areas must be classified using the given criteria. Then the two criteria are considered in order to determine the safety standard. If the protected area meets only one criterion, the level is lowered by one. The spatial planning must take the planning for socioeconomic development up to 2020 and the vision for 2050 into consideration. The classification system above is the result of a decision-making process that was informed by evaluations of the individual, societal, and economic risks of flooding in Vietnam (Mai Van, van Gelder, and Vrijling 2010). The system has been used to establish a safety standard for each stretch of Vietnam’s coastal protection system. Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 163 Figure 5.4: International Examples of Societal Risk Guidelines New South Wales Dam Safety Committee Australian National Committee on Large Dams U.S. Army Corps of Engineers Netherlands Guideline for individual dams Guideline for individual dams Guideline for individual dams Guideline for flood risk at the national level Proposed Societal Risk Requirements – Existing Dams Revised ANCOLD Societal Risk Reference Guideline Source: New South Wales Government Dams Safety Committee 2006; ANCOLD 2003; Bureau of Reclamation 2011; Van der Most et al. 2014. Bangladesh: 164 Enhancing Coastal Resilience in a Changing Climate Ismail Ferdous Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 165 • Economic risk is typically measured in terms of the annual expected 5.3. Risk-Informed Planning losses of the direct and indirect economic impacts of a hazardous event. Economic risk plays a role in project appraisal and the optimization of Coastal resilience is an ongoing process that requires careful planning. Funds risk management actions. The former involves comparing the costs and are limited and organizational resources are finite. Priorities must therefore benefits of interventions, the latter balancing the cost of risk reduction be established. As an example, the BDP 2100 lists three separate, yet related, (that is, the investment and maintenance costs of interventions) against strategies for flood risk management. The first strategy concerns the protection the reduction in economic risk. Here it is important to realize that the of economic strongholds and critical infrastructure. The second strategy dollar value of damages to assets and production losses is not necessarily focuses on the maintenance and redesign of flood risk reduction schemes a good proxy for aggregate welfare loss. Losing a dollar is likely to mean to prepare them for the future. The third strategy outlines the protection of less to a millionaire than a poor person. How to account for distribution in the livelihoods of vulnerable communities. Implementing these strategies will the evaluation of total output has occupied scholars since the early days require considerable time and effort. This necessitates the prioritization of risk of welfare economics and cost-benefit analysis (Hicks 1939; Kaldor 1939; management actions and the design of risk management programs in ways Arrow 1963). The matter is particularly relevant in evaluating DRR projects that are consistent with these long-term goals. for the poor, since a focus on damage to assets and production losses may mean a lack of emphasis on the plight of the poor (Hallegatte et al. 2017). Using risk in the planning process improves the effectiveness of disaster For instance, a study focusing on the impacts of Cyclone Sidr in coastal reduction plans. Flood defenses, dredging, EWS, and shelters all impact coastal Bangladesh found that poor households experienced on average 7 percent resilience in different ways. Yet their benefits can be measured in terms of of the asset damages but 42 percent of the welfare losses (Verschuur et al. risk reduction. As such, risk provides a basis for comparing and prioritizing 2020). seemingly incomparable interventions, and for establishing the optimal mix of measures for selected regions. As an example, shelters and flood defenses The BDP 2100 lists several general principles that could be used as the starting both reduce life safety risks. Building shelters may therefore lower the urgency point for developing tolerable risk guidelines for natural hazards in Bangladesh. of upgrading flood defenses, and vice versa. Hence, when shelter and flood Turning principles such as “leave no one behind,” “support economic protection programs are developed in conjunction rather than in isolation, development,” and “climate-proof Bangladesh” into practical decision- efficiencies will likely be gained due to better alignment. making guidelines could lead to a tolerable risk management framework of the type used in other countries. For instance, an individual risk guideline For instance, large synergies between interventions were found when could give substance to the principle to “leave no one behind.” After all, such constructing portfolios of interventions to reduce both damage and welfare a guideline could be a tool for identifying those that are disproportionately losses from cyclones (Verschuur et al. 2020). These portfolios of interventions at risk. Similarly, the principle that interventions should “support economic combine protective interventions with interventions that reduce vulnerability development” could easily be related to guidelines for cost-benefit testing. This (such as improved housing and preparedness) and increase the coping and way of operationalizing the general principles from the BDP 2100 would be recovery ability of households (for example, post-disaster support). This clearly very similar to the way in which policy objectives were translated into tolerable demonstrates the added value of having a risk-based framework to evaluate risk guidelines in the Dutch Delta Programme. the benefits of various interventions in a coherent way. Stronger coordination to align the objectives in terms of risk reduction and define the synergies and trade-offs between various interventions could thus increase their effectiveness. Bangladesh: 166 Enhancing Coastal Resilience in a Changing Climate Nonetheless, the interventions can still be implemented under separate In addition to understanding present risks, it is imperative to understand how programs as long as they are not planned in silos. hazard, exposure, and vulnerability may change over time. The precise impact of climate change on, for instance, sea levels, weather patterns, salinity, erosion, • A prerequisite for risk-informed planning is the availability of information cyclone paths, and the strength of cyclones, is highly uncertain. The same about the level of risk and the underlying hazard, exposure, and vulnerability. applies to economic development, changes in land use, population growth, Hazard and risk maps are typically used to depict the extent and intensity and shifting community preferences. When certain types of risk management of hazards and the magnitude of risk. These maps are used by agencies actions perform differently under varying future conditions, the optimal mix of worldwide to support risk-informed decision-making and facilitate measures may change in ways that are impossible to predict. Alternative risk communication among stakeholders. The EU Floods Directive, for instance, evaluation methods, such as robustness or adaptation pathways analyses as obligates all European Union (EU) member states to develop flood hazard described in the BDP 2100, can indicate to what extent decision alternatives and risk maps, and to draw up flood risk management plans for areas at risk of flooding. These maps and plans must be reviewed every six years. Figure 5.5: Flood Hazard Map for Kyoto City, Minami-ku As another example, the Japanese Flood Fighting Act of 2005 obligates municipalities to prepare and distribute flood hazard maps, and to keep them up to date (Figure 5.5). These maps serve to help residents act appropriately in case of flooding, and support municipalities in developing flood management plans and guidelines for land-use planning (Japan MLIT 2005; Udmale et al. 2019). In all of these cases, the level of detail and the information shown is tailored to local use. The Bangladesh Risk Atlas (Department of Disaster Management 2017), which was developed by the GoB, provides valuable insight into the hazards, risks, and vulnerabilities throughout the country for a range of natural hazards. As an example, Figure 5.6 shows storm surge inundation maps for 25- and 50-year return periods for the entire coastal zone. Maps such as these are essential for, among others, risk-informed decision-making on national and regional priorities, developing action plans, and informing the people at risk. Yet, unlike the abovementioned examples from other countries, the Risk Atlas was not developed as part of a broader and continuous institutional design or risk management process that ensures it remains up to date and is embedded in the different planning activities. The experiences from other countries underline the importance of developing maps with a specific application in mind to ensure that they meet the information needs of their users. Source: Udmale et al. 2019. Note: The map provides information for citizens on what to expect in case of flooding and where to find shelter. Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 167 Figure 5.6: Storm Surge Inundation Maps for 25- and 50-year Return Periods for Bangladesh Source: Department of Disaster Management 2017. Bangladesh: 168 Enhancing Coastal Resilience in a Changing Climate are able to accommodate potential future changes. Still, uncertainties will To illustrate how risk could be used to support the development of disaster always remain, which should be clearly documented and communicated for reduction plans, a recent study by the World Bank compared different risk-planning purposes. options for protecting Polder 32 against tidal flooding. Polder 32 is located in Khulna District, along the Shibsa river, and was one of the first polders to Fortunately, a risk-informed planning approach is well suited for dealing with be rehabilitated within the CEIP-I (Figure 5.7). The polder has a gross area of present and future uncertainties. This is because risk is all about uncertainty. 8,097 hectares and has a total of 38,400 inhabitants (about 9,600 households). After all, if there were no uncertainty about hazard, exposure, or vulnerability, The main economic activities are agriculture and fish farming. The principles of there would be no risk. In a risk-informed planning approach, uncertainties project appraisal (Box 5.4 and Figure 5.8) were used to study three different are dealt with in a balanced and explicit manner, regardless of whether they strategies for flood risk reduction in the polder: “Hold the Line,” “Set Back,” and concern the hazard, vulnerability, or exposure, lend themselves to statistical “Differentiating Protection” (see Figure 5.9, Figure 5.10, and Figure 5.11). The analysis, or concern the present or the future. For instance, the uncertainty analysis accounted for relative SLR, assumed an economic growth of 3 percent related to mean SLR influences the probability of an embankment being and applied a discount rate of 10 percent (as per CEIP-I documentation). Cost overtopped in a given number of years, much like the uncertainty related to estimates for flood defenses were based on an analysis of the Bill of Quantities the occurrence of an extreme weather event does. Increasing the robustness of the CEIP-I. The total potential damages for Polder 32 were estimated at and flexibility of interventions are two ways to address the uncertainties related US$47 million based on the damage assessment done under the CEIP-I. For to future changes in the design of civil engineering works. In general, this reasons of simplicity, the case study ignored the important distinction between uncertainty can be dealt with by designing measures that are flexible, requiring (in)direct damages and welfare losses. It also ignored the practical difficulties frequent reinvestment, or are robust, with safe margins to absorb uncertain of implementing some of these strategies in Bangladesh’s coastal zone. The future changes. purpose of the case study was merely to illustrate the differences, in terms of costs and benefits, of protection strategies that are used worldwide, whether Various decision-making tools are available that can support the risk-based or not these are implementable at present in Bangladesh (World Bank 2013). planning process of investments in the face of present and future uncertainties (see for example Kalra et al. 2014). The key difference between these “robust” In Polder 32, the expected annual damage from tidal flooding is relatively high decision-making tools and the traditional approach is how uncertain future and it is expected to continue to increase in the future, which provides a strong scenarios are handled. Traditionally, the decision-making process was designed rationale for a significant investment in flood protection. Prior to the CEIP-I, to agree upfront on various assumptions regarding future climate change Polder 32 was surrounded by embankments protecting the land against high or socioeconomic scenarios, thereby often greatly limiting the number of tides, with an estimated level of protection of (only) a one in 10-year return scenarios. In addition, the assumptions could be biased and did not reflect period. If flooded, the total direct damage is estimated at US$47 million. A first the inherent uncertainty that is associated with the long-term future. Robust order estimate of the flood risk in the polder is about US$5 million per year decision-making tools evaluate interventions for a large number of uncertain (probability times damage). In the next 30 years, which is the design lifetime of scenarios, improving the likelihood that decisions (for example, infrastructure the interventions in the CEIP-I, the risk of flooding is expected to increase ten- upgrades) will perform well under a large variety of future scenarios. This is fold to about US$50 million per year, due to the combined effects of subsidence often referred to as decision-making under deep uncertainty, and various tools and SLR, as well as economic growth (~3 percent per year in the agricultural exist with successful applications, including managing flood risk (see for an sector in Bangladesh). The net present value of the expected damages over overview Marchau et al. 2019). this period amounts to about US$125 million. This amount could serve as a Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 169 Figure 5.7: Polders in the Coastal Zone of Bangladesh (left) and a Map of Polder 32 (right) Source: CEIP-I project documents. reference for evaluating investments to reduce the risk of tidal flooding. protection level turns out to be slightly higher than that adopted in the CEIP-I and varies between protection levels corresponding to the 50- to 100-year The current strategy of the CEIP-I for Polder 32 is to provide flood protection return period. However, satisfying the 25-year protection level during a design against a level of one in 25 per year throughout the lifetime of the project working life of 30 years is likely to require extensive maintenance and additional by upgrading the existing polder embankment alignment. These upgrades bank and slope protection works, which have currently not been accounted for include heightening embankments and providing bank and slope protection in this calculation. Considering this, the 25-year protection level in the CEIP-I at locations that are currently vulnerable to erosion (about 5 percent of the appears to be broadly reasonable from an economic perspective. polder perimeter). This strategy has a benefit-cost ratio of about 3. The optimal Bangladesh: 170 Enhancing Coastal Resilience in a Changing Climate Box 5.4: Project Appraisal and Optimization A “Hold the Line” strategy, with extensive bank and slope protection to maintain the current polder alignment, can be cost-effective if the necessary Project appraisal is often based on cost-benefit analyses, the criterion being a upgrades are limited to 50 percent of the total length of the polder embankment. minimum benefit-cost ratio, internal rate of return, or net present value. The The key difference with the strategy of the CEIP-I concerns the lowering of costs consist of the initial investment and the present value of the subsequent O&M costs during the lifetime of the project due to larger upfront investments O&M cost. The benefits expressed in the potential risk reduction are estimated in bank and slope protection works. Such works would protect the polder by the present value of the reduction in the economic risk over the lifetime of embankments against bank erosion (up to 10 meters per year) and wave attack a project. from the Shibsa river. If more than 50 percent of the polder’s perimeter requires extensive bank and slope protection works to effectively “hold the line”, then While a project with a certain design standard may have a positive benefit- the costs of such measures would exceed the benefits, making this strategy cost ratio, optimizing the design standards could yield an even higher net ineffective from an economic point of view. The optimal protection level turns present value. This is illustrated in Figure 5.8. The figure shows the cost of out to be slightly lower than the current strategy, varying between a one in 25- flood protection measures (blue line) and the present value of the economic to 100-year event. risk (red line) as a function of the protection level. The green line shows how the total cost (the sum of the investment cost, O&M, recurring investments, and A “Set Back” strategy, in which embankments are moved inland to expected damages) varies with the protection level. The protection level where accommodate bank erosion and avoid additional bank and slope protection, the green line (the total cost of a project over its lifetime) is the lowest is the could be more efficient than the “Hold the Line” strategy, but it would require optimal protection level. major resettlement. This strategy proves most cost effective when the area protected is maximized while avoiding the necessity for bank and slope Figure 5.8: Benefit and Cost of Flood Risk protection. If about 90 percent of the current polder area is maintained, the “Set Back” strategy yields a benefit-cost ratio of about 2 for an optimal protection level of about 250 to 500 years. However, with time, more and more land will be lost, and inhabitants will have to be resettled. Ultimately, the alignment of the embankment will have to be changed again, or bank and slope protection works will have to be carried out in the future to avoid erosion. A “Differentiating Protection” strategy, in which higher protection levels are adopted for areas in Polder 32 with higher economic value, would be relatively cost efficient. The current 25-year protection level appears optimal for agricultural land, while a higher protection level (up to a 250-year level) would be optimal for residential and industrial land use. The polder would effectively be compartmentalized into areas with higher embankments for residential and industrial areas, and lower embankments at the polder’s perimeter to protect the surrounding agricultural land. Besides reducing the probability of (direct) Source: World Bank, original figure developed for this report. Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 171 Figure 5.9: Plan View of “Hold the Line” Strategy economic damages to high-value areas, this strategy could also help lower fatality risk if inhabitants are resettled to the areas that are best protected or are able to reach these safe havens in case of imminent danger. In summary, the case study of Polder 32 shows how the current 25-year protection level (applied in the CEIP-I) seems to be a reasonable protection level for individual polders with predominantly agricultural land use, while higher protection levels (100- to 250-year) seem justified for areas that are mainly used for residential and industrial purposes. Table 5.2 provides an overview of the costs and benefits of each of the abovementioned strategies. This case study only looked at Polder 32. This type of analysis could also be used for evaluating alternative protection strategies at the coastal system level (multiple polders). Examples include adopting a more flexible polder alignment, building safe havens, combining multiple polders to shorten the coastline, or reclaiming land and constructing new polders. Figure 5.10: Plan View of “Set Back” Strategy Also, the case study considered a simplified situation with only one future growth and SLR scenario to show the potential of using risk to support decision-making. For further development and real-life applications, the presented risk-based approach should be further extended by modeling many future climate and socioeconomic scenarios and evaluating the behavior of the various polder strategies. This will generate a deeper understanding of the effectiveness of these strategies under a large range of possible future scenarios to support a well-informed decision. Table 5.2: Comparison of Polder 32 Protection Strategies Cost (US$ Benefit (US$ Benefit-Cost Optimal Protection Level million) million) Ratio CEIP-I 30 95 3 50 to 100-year Hold the Line 112 114 1 25 to 100-year Figure 5.11: Plan View of “Differentiating Protec- Set Back 43 91 2 250 to 500-year tion” Strategy Differentiating 10 45 4.5 25 to 250-year Protection Source: World Bank, original table compiled for this report. Measuring the impact of flooding in terms of welfare losses rather than asset and production losses would place greater weight on the consequences of flooding. Doing so would lead to higher benefit- cost ratios than those shown in Table 5.2. It would also lead to higher optimal protection levels (that is, smaller probabilities of flooding). For instance, differentiating between protection levels and realigning embankments would still appear more efficient than “holding the line.” This, however, ignores the difficulty of implementing such strategies. For instance, successfully implementing a strategy that Bangladesh: 172 Enhancing Coastal Resilience in a Changing Climate involves resettlement, such as in Japan (see Box 5.5), is fraught with difficulty in a place such as Bangladesh’s coastal zone. Issues such as land scarcity, illiteracy, Box 5.5: Flood Protection and Resettlement in Japan the absence of an easily accessible land registry, and complex bureaucratic approval processes make it difficult to carry out projects that involve large- In Japan, building ring levees around vulnerable areas or building scale land acquisition and resettlement secondary embankments may sometimes be more cost effective than building or upgrading primary river embankments (Figure 5.12). 5.4. Risk-Based Design Yet such solutions could leave some people highly exposed, thereby The essence of risk-based design is to ensure that designs satisfy tolerable requiring them to resettle to safer places. In 2010, the Japanese National risk guidelines that are established within the risk management framework. Government launched a subsidy system to provide financial assistance Designing measures based on the same tolerable risk guidelines that are for resettling residents from flood-prone areas if this makes it possible used for strategic planning and O&M ensures consistency throughout the risk to more efficiently protect areas from flood protection. management process. If, for instance, the selection of a DRR plan is based on economic considerations, design criteria could similarly be based on economic Figure 5.12: Japanese Flood Control Measures in Concert with Land considerations. As an example, the case study for Polder 32 from Section 5.3 Use showed how optimal protection levels could be obtained from cost-benefit analysis. To achieve such levels in practice, however, guidelines are needed for the design of coastal embankments that are tailored to these protection levels. Developing risk-based design guidelines involves several simplifications. By considering the consequences of a failure (such as a flood with a certain economic loss) as a given, a tolerable risk guideline yields a target failure probability (Figure 5.13). A target failure probability (protection level) can then be used as a basis for probabilistic design. This involves estimating the probability of failure of a design using advanced statistical methods. Since probabilistic design is relatively complex, the use of a Load and Resistance Factor Design (LRFD) method is more common in practice. This method involves the use of design guidelines with safety factors that are calibrated to target failure probabilities. Such LRFD methods are also called semi-probabilistic design methods since they approximate the results of probabilistic analyses. These LRFD-based guidelines are used worldwide for the design of civil engineering works, in for instance, the United States, the EU (in its technical design standards known as Eurocodes), Mozambique, Malaysia, and Vietnam.22 Source: van Alphen et al. 2011. Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 173 Figure 5.13: From Tolerable Risk to Calibrated LRFD-based Guidelines Distinguishing between ULS and SLS in the design of coastal embankments in Bangladesh can save costs. Bangladesh’s coastal embankments may sustain heavy damage without being breached. This is illustrated by the performance of flood defenses during recent cyclone events. The following images show damage (SLS exceedance) without breaches (ULS exceedance). This means that the probability that an embankment segment is breached is likely to be lower than 25-year when embankments are designed to withstand a 25- year overtopping discharge without substantial damage, as is the case in the CEIP-I. This difference between ULS and SLS is expected to be considerable for overtopping failures due to the relatively short duration of large- scale overtopping. Defining the ULS more accurately may show that lower embankments will suffice for the same tolerable risk level, freeing up resources for use elsewhere. Furthermore, the use of more advanced probabilistic methods could help to optimize design. As an example, consider the design of slope protections. The slopes of embankments are currently protected using blocks of the same size Source: World Bank, original figure developed for this report. based on the design for a 25-year wave height. Yet the required block size could vary along the slope of an embankment. This is because cyclone events that generate relatively high waves often also generate relatively high water levels. Since the consequences of damage to a structure and a complete failure of Hence, the highest wave impacts most likely occur at higher water levels. Larger a structure are not the same, design guidelines distinguish between different blocks are then required higher up a slope, whereas smaller blocks suffice lower limit states. According to Eurocode EN1990, section 1.5.2.12, limit states down. Slope protections in the Netherlands are designed with the dependence are “states beyond which the structure no longer fulfils the relevant design between water levels and wave conditions taken into consideration (Box 5.6). criteria.” Defining limit states is essentially about defining failure. In general, a This yields more cost-effective designs, with protection measures that are distinction can be made between Ultimate Limit States (ULS) and Serviceability tailored to the hydraulic conditions at various parts of the structure. Limit States (SLS). ULS are “states associated with collapse or with other similar forms of structural failure” (Eurocode EN1990, section 1.5.2.13). SLS are “states To be able to improve design guidelines from a risk perspective, more that correspond to conditions beyond which specified service requirements for information is needed concerning both the load side and the strength side a structure or structural member are no longer met” (Eurocode EN1990, section of embankment design. For instance, on the load side, optimizing the design 1.5.2.14). Since the consequences of SLS exceedances are typically smaller than of slope protection works requires wave statistics for given water surface those of ULS exceedances, the target failure probabilities for the SLS are typically elevations. Such statistics are not yet available. However, the IWM has already less strict than those for the ULS. As an example, the economically optimal developed an advanced probabilistic hazard model for the design of coastal probability of damage to a flood defense (SLS exceedance) is typically smaller embankments (IWM 2018), which is based on computer simulations of historic than the economically optimal probability of flooding (ULS exceedance). cyclones. The hazard model is used in the CEIP-I for separately estimating Bangladesh: 174 Enhancing Coastal Resilience in a Changing Climate 25-year water levels and 25-year wave heights. Yet in principle, it is possible coastal zone using physics-of-failure models from other countries. The results to derive joint distributions from simulation-based hazard models, as well as from in-situ overtopping experiments performed in the Netherlands and the probability distributions for the wave height and wave period for given Vietnam simply cannot be generalized to embankments in Bangladesh, where water levels. On the strength side, optimizing the design of slope protection grass covers have different characteristics. Country-specific experiments and in- works requires accurate methods for predicting the stability of armour units situ tests will be essential for making it possible to move embankment design under extreme wave conditions. The design formulas for single layer cubes methods forward. Considering the sheer length of embankments in the coastal used in the CEIP-I may include safe margins that make them unsuitable for zone, even small improvements could pay large dividends in the long term. use in probabilistic analyses. This means that new methods would have to be developed, which may require wave flume experiments. Good quality physics- 5.5. Operation and Maintenance of-failure methods are also required for making the distinction between ULS and SLS. For instance, a breach due to overtopping is initiated not only from O&M is an essential component of the risk management process. While damage to the grass cover, but also to progressive erosion, which is harder to monitoring is sometimes portrayed as separate from O&M, it is treated as an predict using empirical formulas. It is hitherto unclear when a grass-covered integral part of O&M in the remainder of this section. As such, O&M includes embankment or an embankment made of locally sourced clay will start to both routine and non-routine inspections, the use of advanced monitoring erode, given that most existing empirical formulas are based on experiments systems, preventive maintenance, and repairs. O&M is vital to ensure that issues using other types of materials. are identified and addressed before they are too costly to resolve. O&M has to be a recurrent activity during the entire lifetime of a project. It also provides the Pursuing these research opportunities will require time and effort but given information that is needed for strategic planning and adaptation. In short, O&M the 6,000 kilometers of embankments in the coastal zone, it will surely pay is what turns the risk management process into a truly continuous process. off. Differences in soil properties, construction methods, and vegetation make it impossible to accurately predict the performance of embankments in the Damage to the landside slope of a coastal embankment from overtopping caused by Cyclone Sidr. Photo credit: Government of Bangladesh 2008 (first 2 photos); Islam et al. 2011 (right photo). Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 175 Box 5.6: Slope Protection Design in the Netherlands Slope protections in the Netherlands are designed using hydraulic load models that account for the dependence between water levels, wave loads, and the angle of wave incidence. This makes it possible to tailor the design of slope protections to the varying design wave load along the outer slope of a sea dike. The example shown in Figure 5.14 shows the design of a slope protection for a sea dike in the Netherlands. The largest blocks are placed in the zone just below the berm, where the design loads are highest. Above the berm, a grass cover suffices. Developing similar load models for optimizing the design of slope protections in Bangladesh’s coastal zone could yield considerable cost savings considering the hundreds of kilometers of flood defenses that have to be protected from wave attack. Figure 5.14: Design of Slope Protection for the Sea Dike at Biezelingsche Ham in Zeeland, the Netherlands Berm / maintenance path Columns Grass cover (0.3m/2300 kg/m3) Columns (0.3m/2300 kg/m3) Blocks Columns Clay Avg. High Water (0.3m/2300 kg/m3) Geotextile Toe structure Source: World Bank, original figure developed for this report. Bangladesh: 176 Enhancing Coastal Resilience in a Changing Climate BANGLADESH COASTAL RESILIENCE 03 Aerial image of the sea dike at Biezelingsche Ham in Zeeland, the Netherlands. (Photo from https://beeldbank.rws.nl/MediaObject/Details/503542.) Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 177 BANGLADESH CHAPTERCOASTAL 5 RESILIENCE 02 03 Well-organized O&M activities can save considerable costs. In reality, however, Putting a price on O&M inadequacies may help to (re)direct strategic investments budgetary, organizational, and political constraints can easily lead to a focus on to this prerequisite for successful risk management. For instance, assuming grand schemes rather than mundane O&M needs. Inadequate O&M may give newly restored flood defenses will perform as designed for a period of 30 years rise to a rapid and uneconomical need for restoration or renewal. For example, only seems realistic with a professionally organized and fully funded O&M unchecked bank erosion can lead to the loss of an entire flood defense. Also, scheme in place. Without adequate O&M, another round of restoration activity minor damage to slope protection, such as a single missing block or small crack, will probably be necessary within 30 years, or the early loss of functionality will can strongly affect the stability of the entire slope protection under extreme have to be accepted. Using realistic assumptions in the cost-benefit analyses wave conditions. Since restoring flood defenses is typically far more expensive about the O&M state of practice will lower the benefit-cost ratios of projects than maintaining existing ones, the gains from O&M often far exceed its costs. that do not involve adequate O&M relative to those that do. Making O&M part of the equation will help to give sound O&M practices the attention they Therefore, efficient risk management frameworks include mechanisms to deserve and will be essential to closing the risk management cycle. ensure that O&M is given sufficient attention. Such mechanisms could take Figure 5.15: The Widening O&M Funding Gap for FCDI Projects many forms. For example, the Dutch Regional Water Authorities have a statutory duty of care for the primary flood defenses they own and operate (see Box 5.2). O&M serves to prevent avoidable degradation and damage from encroachments and hence, the need for restoration projects. Involving local communities in O&M practices could also be an effective way to strengthen the position of O&M in the risk management process. Such an approach is currently being piloted in the CEIP-I, where local communities are given minor responsibilities for the maintenance of flood control, drainage, and irrigation (FCDI) works. O&M in Bangladesh suffers from a lack of resources. This was confirmed by the BDP 2100 baseline study on water resources, as shown in Figure 5.15. Rather than becoming smaller, the funding gap for FCDI projects has grown considerably, and is set to widen even further in the years to come. This not only hinders maintenance and repairs, but also forms an obstacle to monitoring and Source: General Economics Division, Bangladesh Planning Commission 2018. inspections, which are essential for taking informed and timely measures. For instance, assessments and predictions of bank erosion are largely based on site visits in response to local people reporting bank erosion. Routine monitoring, satellite imagery, and bathymetric surveys could help to identify where bank protection is needed before it is too late, and another round of embankment restoration is needed (Box 5.7). Bangladesh: 178 Enhancing Coastal Resilience in a Changing Climate Box 5.7: Advances in Monitoring Riverbank Erosion 5.6. Notes 22. The latter three countries have adopted or are in the process of adopting the In Bangladesh, riverbank erosion occurs simultaneously at many Eurocodes, like many non-EU countries. places in vast and remote areas. This poses great challenges to the monitoring required for the identification of erosion hotspots and the 23. See https://aqua-monitor.appspot.com/. prioritization and design of interventions. Remote sensing is a powerful tool to assist with this. Retreating riverbanks because of erosion can be derived from comparing the water and land distinctions on satellite 5.7. References images from different years, as illustrated by the Aqua Monitor.23 These ANCOLD. 2003. Guidelines on Risk Assessment. Australian National Committee on Large multitemporal images can be based on visible or infrared light, but also Dams, Hobart, Tasmania. on radar, which has the advantage that it is not hindered by the clouds Arrow, K. J. 1963. Social Choice & Individual Values. Second ed. New Haven and London: that abound during the monsoon season. Yale University Press. Ball, D. J. and P. J. Floyd. 1998. Societal Risks. Bureau of Reclamation. 2011. Dam Safety Public Protection Guidelines, A Risk Framework At erosion hotspots, the conditions and processes responsible for bank to Support Dam Safety Decision-Making - Interim. Department of the Interior, erosion can be monitored in more detail by remote sensing from the Bureau of Reclamation, Dam Safety Office, Denver, Colorado. water surface or the ground, rather than from space. Echosounders Canadian Dam Association. 2007. Dam Safety Guidelines. Edmonton, Alberta, Canada. provide information on water depth and elevation of the riverbed— Department of Disaster Management. 2017. Risk Atlas: Multi-Hazards Risk and Vulnerability Assessment, Modeling and Mapping. Dhaka, Bangladesh. single-beam echosounders in the form of sectional profiles, and General Economics Division, Bangladesh Planning Commission. 2018. Bangladesh Delta multibeam echosounders in the form of bathymetric maps. Acoustic Plan 2100. Dhaka. Available at: https://www.bdp2100kp.gov.bd/Document/ doppler current profilers provide information on the three-dimensional ReportPdfView. flow under water. Radar provides information on flow patterns at the Government of Bangladesh. 2008. Cyclone Sidr in Bangladesh-Damage, Loss and Needs water surface. Flow velocities are also measured by direct contact using Assessment for Disaster Recovery and Reconstruction. Dhaka, Bangladesh. Available at: https://reliefweb.int/sites/reliefweb.int/files/resources/ flow meters and float tracks. The topography of shallow or emerged F2FDFF067EF49C8DC12574DC00455142-Full_Report.pdf. areas is measured by traditional land survey techniques. Hall, J. W., Sally Brown, Robert J. Nicholls, Nick F. Pidgeon, and Robert T. Watson. 2012. “Proportionate Adaptation.” Nature Climate Change 2(12): 833–834. Nature The monitoring of riverbank erosion supports decisions as to whether Publishing Group. doi: 10.1038/nclimate1749. banks need to be protected or buffer zones of permissible erosion need Hallegatte, S., A. Vogt-Schilb, M. Bangalore, and J. Rozenberg. 2017. Unbreakable: Building the Resilience of the Poor in the Face of Natural Disasters. Washington, to be broadened by setting back embankments. Tools for mapping and DC: World Bank. doi: 10.1596/978-1-4648-1003-9. forecasting are hence essential components in addition to the tools Hicks, J. R. 1939. “The Foundations of Welfare Economics.” The Economic Journal for observation and measurement. Geographical information systems 49(196): 696. doi: 10.2307/2225023. provide the tools for mapping. Erosion forecasts can be made through HSE (Health Safety Executive). 2001. Reducing Risks Protecting People, HSE’s Decision an array of methods ranging from simple empirical predictors to Making Process. London, United Kingdom. Islam, A. S., Sujit Bala, Mohammad Hussain, Mohammed Hossain, and Md. Rahman. sophisticated numerical morphodynamic models. 2011. “Performance of Coastal Structures during Cyclone Sidr.” Natural Hazards Review 12(3): 111–116. doi: 10.1061/(ASCE)NH.1527-6996.0000031. Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 179 Ismail Ferdous Bangladesh: 180 Enhancing Coastal Resilience in a Changing Climate IWM. 2018. Technical Report on Storm Surge, Wave, Hydrodynamic Modelling and Udmale, P., Yasuto Tachikawa, Kenichiro Kobayashi, and Takahiro Sayama. 2019. “Flood Design Parameters on Drainage System and Embankment Crest Level, Volume Hazard Mapping in Japan.” In Catalogue of Hydrologic Analysis for Asia and I: Package-1. Dhaka, Bangladesh. the Pacific, edited by K. Kobayashi, I. Sutapa, G. Tabios, and Y. Tachikawa, 16– Japan MLIT (Ministry of Land, Infrastructure and Transport). 2005. Flood Hazard Mapping 36. UNESCO-IHP. Manual in Japan. Tokyo, Japan. US FEMA (Federal Emergency Management Agency). 2015. Federal Guidelines for Dam Jonkman, S. N., P. H. A. J. M. van Gelder, and J. K. Vrijling. 2003. “An Overview of Safety Risk Management. Washington, DC. Quantitative Risk Measures for Loss of Life and Economic Damage.” Journal of USACE. 2011. “Levee Safety Program – Non-Routine Activities.” Levee Safety Program Hazardous Materials 99(1): 1–30. doi: 10.1016/S0304-3894(02)00283-2. Paper. Available at: https://levees.org/wp-content/uploads/2012/05/Levee- Jonkman, S. N., J. K. Vrijling, and A. C. W. M. Vrouwenvelder. 2008. “Methods for the Safety-Program-Paper-Web-3-1.pdf. Estimation of Loss of Life due to Floods: A Literature Review and a Proposal USACE. 2014. Safety of Dams – Policy and Procedures. CECW-CE ER 1110-2-1156. for a New Method.” Natural Hazards 46(3): 353–389. doi: 10.1007/s11069-008- Washington, DC. 9227-5. USACE. 2018. A Summary of Risks and Benefits Associated with the USACE Levee Kaldor, N. 1939. “Welfare Propositions of Economics and Interpersonal Comparisons of Portfolio. Utility.” The Economic Journal 49(195): 549. doi: 10.2307/2224835. USACE. n.d. “National Levee Database.” Accessed December 20, 2021. Available at: Kalra, N., S. Hallegatte, R. Lempert, C. Brown, A. Fozzard, S. Gill, and A. Shah. 2014. National Levee Database (army.mil). “Agreeing on Robust Decisions: New Processes for Decision Making under van Alphen, J., L. Bourger, C. Elliott, K. I. Fujita, D. Riedstra, D. Rooke, and K.Tachi. 2011. Deep Uncertainty.” Policy Research Working Paper 6906, World Bank, Flood Risk Management Approaches as Being Practiced in Japan, Netherlands, Washington DC. United Kingdom, and United States. IWR Report No. 2011-R-08. Mai Van, C., P. H. A. J. M. van Gelder, and J. K. Vrijling. 2010. “Risk Based Design of Coastal Van der Most, H. I. Tanczos, KM. De Bruijn, and D. Wagenaar. 2014. “New Risk-Based Flood Defences - A Vietnam Case.” In Reliability, Risk and Safety: Theory and Standards for Flood Protection in the Netherlands.” 6th Int. Conf. Flood Manag., Applications, edited by C. G. Soares and Martorell. London: Taylor & Francis Sao Paulo, Brazil, September 2014. Group. Verschuur, J., E. Koks, A. Haque, and J. Hall. 2020. “Prioritising Resilience Policies to Reduce Marchau, V. A. W. J., W. E. Walker, P. J. T. M. Bloemen, and S.W. Popper (eds.). 2019. Welfare Losses from Natural Disasters: A Case Study for Coastal Bangladesh.” Decision Making under Deep Uncertainty. From Theory to Practice. Springer Global Environmental Change 65(October): 102179. Elsevier Ltd. doi: 10.1016/j. International Publishing. doi: 10.1007/978-3-030-05252-2. gloenvcha.2020.102179. New South Wales Government Dams Safety Committee. 2006. Risk Management Policy Vietnam Ministry of Agriculture and Rural Development. 2010. Technical Guidelines on Framework for Dam Safety. New South Wales, Australia. Sea Dike Design. Hanoi, Vietnam. World Bank. 2013. Project Appraisal Document. Coastal Embankment Improvement Project Phase-I. Dhaka, Bangladesh. Chapter 5: Applying a Risk-Based Approach to Coastal Resilience 181 BUILDING WITH NATURE: INNOVATIVE SOLUTIONS FOR COASTAL RESILIENCE 6.1. Polder 35/1: A Hybrid and Nature-Based Solution for Combating Erosion 6.2.  6.3.  6.4. Opportunities for Integrating Mangroves in Coastal Protection Strategies 6.5. Notes 6.6. References 182 Kuakata Sea Beach (Polder 48): A Hybrid and Multifunctional Solution for Combating Coastal Erosion and Enhancing Tourism Cox’s Bazar: A Hybrid, Nature-Based, and Multifunctional Solution for Combating Coastal Erosion, Preventing Flooding, and Enhancing Tourism Bangladesh: Enhancing Coastal Resilience in a Changing Climate 6 CHAPTER 6: BUILDING WITH NATURE: INNOVATIVE SOLUTIONS FOR COASTAL RESILIENCE Bangladesh has made significant progress in managing disaster risks and in coastal communities, from building disaster shelters and implementing making the coastal region safer through multiple investments in structural and EWS to rehabilitating embankments and stabilizing shorelines through non-structural risk reduction measures and the adoption of extensive legal, large-scale bank and slope protection works. Such traditional infrastructure- regulatory, and policy frameworks to guide coastal development in a safe and focused initiatives have been largely successful, and given the extremely at- sustainable manner. risk coastline, a necessity for the safety of vulnerable coastal communities in Bangladesh. However, Chapter 4 also highlighted that such “grey” infrastructure As discussed in Chapter 4, the GoB has successfully implemented a wide interventions are often expensive, need extensive maintenance, and can range of interventions to lower the risk of tidal flooding and storm surges interfere with the local environment. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 183 This chapter focuses on options for inspirational and innovative solutions that Box 6.1: Combining Green and Grey Nature-Based Solutions in could lower the vulnerability of Bangladesh’s coast, embracing and working Vietnam’s River Deltas with the natural dynamics of the coastal zone, while providing additional benefits to local communities and ecosystems. Such innovative nature-based The Mekong Delta is densely populated and home to 22 percent of Vietnam’s solutions work alongside and take advantage of the forces of nature by, for population, most of whom are near-poor households living in rural coastal instance, using natural currents for transporting sand to combat erosion or areas, highly dependent on rice or shrimp farming for their livelihoods. The redirecting river flows to keep waterways open. Another example is mangrove region is facing increased salinity intrusion, erosion, and flooding from land afforestation and restoration of original mangrove forests to protect local subsidence and SLR in the southern part of the Ca Mau Peninsula that is embankments while providing livelihoods benefits for the local community. affecting the livelihoods of delta communities. These solutions are flexible and adaptable to rising sea levels. The Mekong Delta Integrated Climate Resilience and Sustainable Livelihoods In the face of uncertainties related to future impacts of climate change as well Project used a combined green-grey approach to coastal protection consisting as the need to protect and conserve marine natural resources, nature-based of a mangrove belt outside the sea dike to serve as the first line of defense, solutions, and a mix of green-grey infrastructure (that is, hybrid solutions) are followed by sea dikes (where appropriate), and then a more extensive mangrove increasingly recognized as feasible options. Often hybrid solutions consisting of belt inland of the sea dike. The project also supports subprojects that include a combination of hard structures, such as protection works, and soft measures, the construction of coastal defenses consisting of combinations of compacted such as sand nourishments or vegetation, are found to be economically viable earth embankments and coastal mangrove belts. The nature-based solutions for areas with large population densities and high land value (such as tourist provide flexibility and can adapt to the delta’s natural dynamics and climate or residential areas) (See Box 6.1). Such hybrid solutions can be less intrusive change impacts. This approach has led to increased economic opportunities to natural coastal processes as they consist of dynamic solutions that are more (for example, mangrove shrimp systems) and increased tourism activities in Ca adaptable to changing natural circumstances. They can be cost effective in Mau Province. the long run and offer benefits such as improved livelihoods opportunities, Source: Browder et al. 2019. reduced maintenance costs, and synergies with natural resource systems by conserving and enhancing valuable natural resources. For example, in the CEIP-I, embankments have been combined with mangrove belts to provide a hybrid solution applied in multiple places globally. It can be considered in greater protection as well as reduce the maintenance requirements of the locations with high economic value that are prone to erosion and flooding and embankments. Notably, mangrove restoration in Bangladesh has yielded can generate livelihood opportunities and economic growth (see Box 6.2). a wealth of experience on technical, institutional, and social aspects, and contributed to enhancing coastal resilience. As has been the experience in the This chapter provides several inspirational examples of nature-based and CEIP-I, benefits in terms of protection from storms and erosion, forest products, hybrid design solutions based on a Technical Assistance (TA) that was carried and good community participation ensure the sustainability of the approach. out to develop innovative and integrated conceptual designs for coastal areas of Bangladesh, with specific emphasis on coastal erosion. The purpose was Over the years, innovative hybrid solutions have been developed across the to guide future investment plans for building long-term coastal resilience world that would be suitable for use in Bangladesh. For instance, a multifunctional by operationalizing state-of-the-art knowledge from global experiences and embankment24 in combination with sand nourishment is a good example of incorporating local context into conceptual designs for Bangladesh. The TA had Bangladesh: 184 Enhancing Coastal Resilience in a Changing Climate four phases: Phase 1: inception; Phase 2: review existing practices on Box 6.2: Multifunctional Embankment “Scheveningen Boulevard” in coastal erosion; Phase 3: develop conceptual designs for three coastal the Netherlands hotspots; and Phase 4: scale up the lessons learned from the hotspot analysis and disseminate to a broader audience to inspire resilient and The boulevard at Scheveningen, The Hague, is a good example of combining sustainable coastal investment programs. coastal protection with recreation and tourism. The multifunctional embankment at Scheveningen Boulevard was conceptualized to incorporate a sturdy embankment For the selection of potential sites and design solutions, understanding within the coastal beachfront, improving the relation between land, beach, and the causes of coastal erosion at the various proposed locations was sea. Housing several restaurants and recreation facilities with a beachfront, the imperative. A preliminary assessment analyzed the boundary and boulevard follows the undulating course of the old dunes and has different height environmental conditions. When preparing the conceptual designs, levels that separate pedestrians, cyclists, and motorists. Built between 2009 and the physical and institutional contexts were taken into consideration 2013, the beach was first widened by 50 to 70 meters through sand nourishment by means of field visits and consultation meetings. The physical context over a length of 2 kilometers using 2.6 million cubic meters of sand. A kilometer- was assessed through validation of the proposed design solutions with long multipurpose dike was then constructed, with the boulevard situated on top numerical modeling, considering the boundary and environmental of the dike. conditions. The embankment has several levels that can be accessed by stairs or ramps. The premise was that the conceptual designs should be new, innovative, Additionally, the area below the crest of the embankment is filled with sandy and inspirational, but must also take the Bangladesh local setting into material and in some locations, a hollow area can be created, which can be used account for reasons of practicality of implementation and acceptance. for parking. From a functional point of view, the concept of a multifunctional Artist impressions of the conceptual designs were made to easily embankment involves an underground protection below the embankment that is communicate the solutions to a wide range of stakeholders and invisible to the public, which in the case of an extreme event, would function as the generate comprehension and commitment to the solutions. primary protection. As such, in an extreme event of a 50-year return period, it is expected that the outer paved surfaces of the Scheveningen Boulevard will collapse, The following steps were taken: and the underground seawall will provide the primary protection. In that respect, 1. Review coastal erosion the materials used for construction of the outer layer of the embankment are softer. 2. Assess possible causes 3. Assess the effectiveness and sustainability of past and current Multifunctional embankments fix the shoreline and often embed erosion protection interventions measures to combine protection with improvements in accessibility and mobility, 4. Gain insight into the governance structure regarding coastal recreation, and commercial activities. The key to creating a sustainable solution with erosion management long-term benefits is the integration of flood safety with waterfront development 5. Select three erosion hotspots and beautification of public spaces, with flood safety as the main driver. 6. Assess the coastal system in the selected hotspot locations 7. Propose suitable solutions For more information: 8. Develop conceptual designs https://denhaag.com/en/scheveningen-boulevard and https://youtu.be/ 9. Validate designs based on physical conditions by means of SsaDoyp3fzU. numerical modeling Asif Aminur Rashid Asif Aminur Rashid Asif Aminur Rashid Asif Aminur Rashid Annual Bangla Channel Open Water Swim (16.1 km seaway from Teknaf to St. Martin’s island). Bangladesh: 186 Enhancing Coastal Resilience in a Changing Climate 10. Visualize conceptual designs via illustrations and artist impressions affect hydrographs and reduce the amount of water and sediment distribution 11. Conduct a preliminary cost-benefit analysis to the downstream branches. 12. Upscale potential interventions. An analysis of the system with regard to erosion was made by subdividing As per the TA, three erosion hotspots were selected for which conceptual the coastal zone into four areas with similar morphodynamics, as also outlined design solutions were made to enhance coastal resilience and reduce risk. The in Chapter 2—the Ganges Tidal Plain West, the Ganges Tidal Plain East, the three hotspots were to reflect three distinct coastal erosion processes that are Meghna Deltaic (Estuary) Plain, and the Chattogram Coastal Plain: common in Bangladesh. Given the large number of erosion problems and the diversity, dynamics, and complexity of the Bangladesh coastal system, it was • The Ganges Tidal Plain West is protected against hydrodynamic energy not possible to define three hotspots that cover all the different coastal erosion from the Bay of Bengal by the Sundarbans but is characterized by tidal processes and the different forcing mechanisms (tides, waves, cyclones, SLR) penetration and lateral river migration causing erosion in river bends. The at play in Bangladesh. Also, given the budget and time available, it was agreed polders just north and east of the Sundarbans suffer mostly from erosion at the outset that the analysis would focus on one design with visuals for each from a combination of high river discharge during the monsoon period hotspot. and residual sediment transport. It was envisaged that in the process of developing the conceptual design, • The Ganges Tidal Plain East is characterized by a younger stage of estuary the team would track the various key design decisions (and document the development. The polders facing the sea are subject to coastal erosion, as potential alternatives that were considered) and provide rationale as to why well as being exposed to cyclonic storm surges and waves. Erosion due certain choices were made, given the context of Bangladesh, but also based on to lateral migration of the river branches, cyclone storm surge, and tidal international experience. variation are dominant processes for the polders located more inland. The analysis created a link between prevailing hydrodynamic processes and • The Meghna Deltaic (Estuary) Plain is outbuilding as new land is being the resulting erosion, which enabled the identification of the location-specific formed at a rate faster than the erosion of older land in this area. Most of the main drivers of coastal erosion in the Bangladesh coastal zone. Large parts islands are exposed to cyclonic storm surges and erosion. Some areas are of the coast are affected by erosion as a result of a combination of factors, also increasingly subject to prolonged waterlogging from encroachment and thus require detailed local morphological analysis. The Meghna Estuary and land reclamation, and as a result of closing of the tidal channels. is considered the main source of sediment along the Bangladesh coast, partly transporting sediment towards the west, which is thereafter moved inland into • The Chattogram Coastal Plain is directly exposed to cyclones and storm the many estuaries of the Sundarbans by tidal interactions. In addition, large- surges. Sediment is delivered to the coast by small rivers originating from scale changes and processes contribute to changes in hydrodynamics and the hilly hinterland. The main causes of erosion at this location are the sediment transport in the coastal system, for instance the construction of dams gradients in longshore transport because of wave-driven currents that are in upstream rivers and development of polders, which lead to a reduction in redistributing the sediment along the coastline. the intertidal area of the coastal system. All these developments have affected hydrodynamics and sediment transport, resulting in siltation in the upstream In view of the rationale of selecting hotspots that show an ample range of typical branches and a sediment deficit along the coast. Natural morphodynamics also forcing mechanisms causing erosion and are in parts of the coast with different Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 187 typical characteristics, three hotspots were selected—Polder 35/1, Polder 48, and The erosion hotspots were confirmed in close consultation with the Bangladesh Cox’s Bazar – Teknaf Marine Drive (see Table 6.1 and Figure 6.1). Additionally, stakeholders and the World Bank during the Inception Workshop and both Polder 48 and Cox’s Bazar – Teknaf Marine Drive are considered tourist thereafter. In summary, the rationale used to define the three hotspots includes destinations in Bangladesh, with room for further development of sustainable the following key points: tourist activities. Initial conceptual designs were taken further and validated by mathematical models, and additional information was collected. It was also • Show a wide range of typical forcing mechanisms behind erosion recognized that the 80-kilometer length of Cox’s Bazar – Teknaf Marine Drive • Cover a broad range of types of coastal zones with typical characteristics would not allow for sufficiently detailed conceptual designs, and therefore sub- • Be already known as erosion hotspots hotspots were introduced there, each with a length of some 3 to 6 kilometers. • Enable application at and extension to other sites. During the inception phase, the reason why no hotspots were selected in the Section 6.1 covers an example of a design for Polder 35/1 that combats bank Meghna Deltaic Plain was clarified. In this area, morphologic changes strongly erosion through a combination of traditional and nature-based solutions. depend on various physical factors such as river discharge, wind, waves, tides, Section 6.2 discusses an example of a nature-based design solution for Kuakata and tide-induced circulation currents. The sediment–water dynamics within this Sea Beach (Polder 48) that addresses bank erosion issues and opens new estuary are very complex due to its irregular shape, wide seasonal variations, opportunities for tourism activities. Section 6.3 covers the example of Cox’s- and the role of the tides. In view of the complexity of the Meghna Deltaic Plain, Bazar, where nature-based flood protection works could be embedded in a it would not be realistic to achieve a detailed analysis within the context of design that enhances the area’s economic potential. Finally, Section 6.4 discusses the TA. In addition, the intention of the TA was to develop integrated design how mangrove afforestation programs could help lower the probability of solutions to combat erosion caused by different processes, not to select flooding while enhancing environmental quality. Sections 6.1 to 6.3 are based hotspots that are representative of the entire Bangladesh coast. The approach on the TA described above, and Section 6.4 is based on the findings of another developed here can then be applied to other hotspots governed by different analysis carried out on mapping mangrove opportunities along the coast of processes. Bangladesh using open-source data. Table 6.1: Considerations for Defining the Hotspots Hotspot Coastal Area Main Erosion Threats River Waves Tides Cyclonic waves Storm surge Polder 35/1 Ganges Tidal Plain West √ √ √ Polder 48 Ganges Tidal Plain East √ √ √ √ Cox’s Bazar – Teknaf Marine Drive Chattogram Coastal Plain √ √ √ Source: World Bank 2021a. Bangladesh: 188 Enhancing Coastal Resilience in a Changing Climate Figure 6.1: Overview of the Three Erosion Hotspot Locations for Detailed Analysis the construction of a closure dam, drainage sluices, flushing inlets, and the re-excavation of canals. The polder is home to a population of around 103,876 (2010/2011). The average family size in the polder is about 5.63 people. Among the male population, many in the project area are employed in business (14 percent), in agriculture (13.6 percent), as daily laborers (13.3 percent), in fisheries (7.3 percent), and in services (2.7 percent) for their livelihoods. Among the female population, most are homemakers (57.7 percent), some are daily laborers (2.4 percent), and a few are employed in services (0.6 percent) and tailoring (0.3 percent) (World Bank 2021a). The polder is a low-lying area with an elevation just above MSL surrounded by tidal rivers. The area is hydrologically linked with the Baleshwar River in the east and the south, the Sannasir Khal in the north, and the Bhola River towards the west. The main rivers of the area—the Baleshwar and the Bhola—flow from north to south. During the monsoon, the river flow increases, and rising waters overflow their banks into the floodplains. The rivers are saline throughout the year in the west. In the east, the rivers carry fresh water to the coast during the rainy season and (only) become saline during the dry season. As a result, Source: World Bank 2021a. most of the eastern half of the region remains non- saline throughout the year. The surrounding rivers 6.1. Polder 35/1: A Hybrid and Nature-Based Solution for Combating Erosion have tidal influence with a maximum tidal range of about three meters. Besides tidal flooding, cyclones 6.1.1. Polder Description, Social Context, and Coastal Dynamics can generate a significant storm surge, raising water levels around the polder one to two meters above Polder No. 35/1 is located in two upazilas in Bagerhat District: Sharankhola and Morelganj. The polder lies normal tide levels, depending on the track and in the agro-ecological zone of the Ganges Tidal Plain West and was originally constructed between 1961 intensity of the storm. and 1968 under the CEP. Over the last few decades, several infrastructure works have taken place, including Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 189 The polder protects agricultural land from salinity intrusion caused by tidal Figure 6.2: Land Use in Polder 35/1 inundation from the sea and adjacent river. Siltation of rivers and channels causes drainage congestion and waterlogging during the monsoons, while natural hazards (such as cyclones and storm surges) threaten agricultural production. Scarcity of suitable non-saline water for irrigation during the dry months (December through April) is a major impediment to the expansion of irrigated agriculture in the polder. The polder contains about 10,400 hectares of net cultivable area, which is about 80 percent of the entire polder area. The remaining 20 percent is used by settlements, water bodies, and other road and water management infrastructure. Of the net cultivable area, single-, double-, and triple-cropped areas amount to about 49 percent, 40 percent, and 11 percent, respectively. The overall cropping intensity of the polder area is about 162 percent. The conditions prevailing in the area limit the variety of crops grown, with rice being the main crop because of its adaptability to diverse ecological conditions (Figure 6.2). Polder 35/1 is currently being rehabilitated as part of the CEIP-I. This includes bank and slope protection works to prevent erosion of the riverbank and embankment slopes as well as rehabilitation of embankments, which includes crest level heightening to mitigate SLR and extreme surge events, and retirement and resectioning of embankments that are or have been under threat of erosion. Generally, the existing embankment around Polder 35/1 is located approximately 50 to 100 meters from the present riverbank. However, at some locations it has reached the toe and the slope of the embankment. Over a stretch of 4 kilometers, significant slope protection works (with concrete blocks) have been carried out to prevent further erosion of the embankments that are now under wave attack (Figure 6.3). The works also include replacement or construction of new structures to improve the drainage system, such as drainage sluices and flushing inlets. A specific design challenge in Polder 35/1 remains the riverbank erosion in the Bogi25 area along the Baleshwar River (see Figure 6.4). As part of the CEIP-I, emergency embankment repair works have been carried out along this river stretch to prevent flood water intrusion into the polder area from riverbank erosion. The emergency temporary measures included earthworks, geobags, and wooden bullah. The CEIP-I is currently enhancing the emergency protection works in this area, as their condition is rather poor. The cost of implementing a Source: CEIP-I project documents. Bangladesh: 190 Enhancing Coastal Resilience in a Changing Climate Figure 6.3: CEIP-I Interventions in Polder 35/1 complete bank protection in this area is high, warranting the need for further investigation of potential design alternatives to combat further bank erosion and the loss of part of the land to the river. 6.1.2. Riverbank Erosion in Bogi The erosion hotspot is located at the southeastern side of the polder, where it is bordered by an outer bend of the Baleshwar River. The river is significantly influenced by the tides, reflected by a high tidal range of over 3 meters during spring tides in the dry season. In contrast, during monsoons, the water levels rise about 60 centimeters from increased river discharge. The erosion at this location (Figure 6.5) has caused a very steep river profile, as the flow channel is protruding into the polder, with the highest flow velocity located close to the existing riverbank. Figure 6.6 shows the bed profile at the hotspot, with a steep profile of 1:1 to 1:2 from -10 mPWD upwards to ~1.5 mPWD at the riverbank. Opposite the erosion hotspot, along the eastern riverbank, is a river char. Satellite imagery of the water line over a period of 30 years reveals an almost linear erosion of the banks at the erosion hotspot in the order of 10 meters per year. At the erosion hotspot, the riverbed topography (Figure 6.7) shows a straight main channel upstream that is attached to the east bank in the north and the erosion hotspot in the south. This suggests that ebb currents are stronger than flood currents. More detailed analyses, as part of the CEIP-I ( CEIP-I 2019), show that recently (2019) an ebb chute has developed, which incises at the northwestern side of the char (see the upper arrow). Simultaneously, the shoal at the southwestern side of the char has increased in height and extended in a southwesterly direction (see lower arrow). These linear bank erosion trends do not show or identify sudden changes to the bed topography, which could have been induced by events like cyclones. Therefore, the analyses suggest that the erosive behavior of the hotspot is more structural than event driven. Source: CEIP-I project documents. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 191 Figure 6.4: Works Undertaken by the CEIP-I in the Bogi Area of Polder 35/1 J. H. Laboyrie J. H. Laboyrie J. H. Laboyrie North direction 20+700 km. North direction 21+500 km. North direction 22+700 km. J. H. Laboyrie J. H. Laboyrie J. H. Laboyrie North direction chainage 24+000 km – initiation South direction chainage 24+000 km emergency Existing char in Baleshwar River. of works for retiring embankment. protection works. Source: CEIP-I project documents. Bangladesh: 192 Enhancing Coastal Resilience in a Changing Climate Figure 6.5: Erosion Hotspot, Southeastern Side of Polder 35/1 (left) and Erosion Rates (right) Shoreline Position [m] Source: World Bank 2021a. Figure 6.6: Schematic Representation of the Present Situation with Basic Di- 6.1.3. A Hybrid Approach to Riverbank Protection mensions in Two Cross Sections Originally, only bank protection works were considered for combating erosion along the riverbanks of Polder 35/1. Bank protection in Bangladesh typically consists of various layers of small concrete blocks or a layered system of geobags with concrete blocks on top that are placed against the eroding riverbank. Since the river channel is very deep, a large volume of material is needed. On top of that, extra material is necessary at the toe of this construction to mitigate ongoing toe erosion (“falling apron”). The typical cost for this type of bank protection in the coastal zone of Bangladesh is in the order of US$4 to US$8 million per kilometer under the CEIP-I and is a major cost component of the overall program. A hybrid approach has been developed that combines dredging as a primary measure and bank protection works as a secondary measure to deal with the bank erosion along this polder. Based on the morphological analysis, the Source: World Bank 2021a. primary idea of the hybrid approach is to reduce the erosion pressure on the Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 193 Figure 6.7: Observed Bed Topography of the Baleshwar River during (from left to right): 2009, 2011, 2015, and 2019 Source: World Bank 2021a. Note: The red line along the bank indicates the erosion hotspot considered. Bangladesh: 194 Enhancing Coastal Resilience in a Changing Climate coastline by accelerating the current morphodynamic development of the river. The hybrid solution limits the need for bank protection works along the This is done by dredging an additional channel in the river, optionally combined entire riverbank by reducing the acting forces on the banks. While this hybrid with a sediment disposal (nourishment) at the erosion hotspot. The dredged solution may limit the total length of bank protection works needed, it will not channel in the center of the Baleshwar River would provoke this channel to replace them entirely. However, the remaining bank protection needed can be enlarge and take most of the hydrodynamic conveyance, thus relieving flow designed against lower current velocities with lower capital and maintenance and the associated erosion of the Baleshwar riverbanks. In addition, depositing costs. Figure 6.9 shows an artist’s birds-eye view impression and provides an the dredged material along the riverbanks would further enforce flow through illustration of how the Bogi area would look with the proposed hybrid solution. the dredged channel and reduce (or even halt) bank erosion. Two project Additionally, using an EEWS in combination with the proposed dredging examples that have approached the subject of changing the loads in a similar solution could facilitate monitoring the rate of erosion at the riverbank where manner are the Payra River dredging project (Islam and Al Kibriya, n. d.) and a the material is dumped and also the backfilling rate in the channel. project in Westkappelle in the Netherlands (Deltares 2014). The combined cost of the hybrid solution with dredging works and limited Four dredging alternatives were explored, and their effectiveness was evaluated bank protection works represents a significant savings in initial costs compared with numerical modeling. The simulations tested the impact of several lengths to the original solution of only bank protection works, with similar annual and depths of the proposed channels on the morphodynamic behavior of the maintenance costs. The main reason for the lower initial cost is the reduced river (Figure 6.8). A shallow, shorter channel (original channel length reduced length of bank protection works needed (about 3.5 kilometers less). A channel by 30 percent) appears an attractive alternative in combination with a sediment of some 3.25 kilometers in length and a dredging level of -9m PWD proved disposal at the Polder 35/1 bank and at the opposite side of the river (Alternative most economical to deal with erosion in this area. The shorter, shallower 1). The shorter channel attracts flow and thereby reduces the current velocities channel moves the river flow away from the riverbanks, thus reducing the need at the riverbank, which in turn reduces the bank erosion significantly. Therefore, for (and cost of) substantial bank protection works. In addition to yielding cost a channel of some 4.5 kilometers in length and a dredging level of a -9 meter savings, it substantially lowers the risk of flooding to local communities in new PWD proved most attractive in terms of reduction of current loads along Polder 35/1 because of a lower risk of embankment breaching. With that, the the riverbanks of the erosion hotspot (the Bogi area). Subsequently, this would hybrid solution could be an attractive alternative to using only bank protection result in a decrease of the annual average erosion rate while also causing limited works. backfilling rates of the dredged channel and, therefore, limited maintenance requirements. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 195 J. H. Laboyrie Figure 6.8: Proposed Dredging and Dumping Alternatives to Reduce Erosion at Polder 35/1. Alternative 0 Alternative 1 Bangladesh: 196 Enhancing Coastal Resilience in a Changing Climate Alternative 2 Alternative 3 Source: World Bank 2021a. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 197 Figure 6.9: Artist Impressions: Birds-Eye View and Typical Cross Section of Proposed Hybrid Solution A Bangladesh: 198 Enhancing Coastal Resilience in a Changing Climate A Typical Cross Section of Proposed Hybrid Solution Source: World Bank 2021a. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 199 6.2. Kuakata Sea Beach (Polder 48): A Hybrid and Multifunctional Kuakata Sea Beach, located in the southern part of Polder 48, has the potential Solution for Combating Coastal Erosion and Enhancing Tourism to become one of the major tourist attractions of Bangladesh. This is the second largest beach of the southern part of Bangladesh and attracts a large 6.2.1. Polder Description, Social Context, and Coastal Dynamics number of Bangladeshi tourists. If the beach is developed to its full potential, it could further contribute to the livelihoods and socioeconomic development Polder 48 is located in Kalapara upazila in Patuakhali District. It is home to of local communities. It is about 70 kilometers from the district headquarters of 44,168 people spread over 9,846 households and has a total area of 5,087 Patuakhali, 320 kilometers from Dhaka, and about a one-hour trawler journey hectares. Of the total population (44,168 people), 7,403 (16.8 percent) are from the Sundarbans. Infrastructure development and marketing are essential economically active—3,744 (41 percent) are employed, 121 (1.3 percent) are to take this tourism destination to the international level. looking for jobs/work, and 3,538 (37.8 percent) are engaged in household work. The main income in the polder comes from agriculture, with about 3,715 The foreshore at Kuakata Sea Beach is a long sandy expanse that used to be hectares of net cultivable area and an overall cropping intensity of 157 percent very wide, but over the years has decreased in width because of coastal erosion. (2012) (Table 6.2). Besides agriculture, the polder provides opportunities for The beach ridge is a continuous linear mound of rather coarser sediment tourism, fisheries, and livestock (World Bank 2021a). near the high-water line. The erosion is caused by longshore and cross-shore sand transport. Longshore transport of sand is caused by daily regular wave Polder 48 is a rather flat, low-lying polder located within a saline tidal floodplain. conditions that move the sand to the adjacent coast just west and east of the There is a wide foreshore along the embankment at the southeastern side of the beach. Cross-shore transport, however, is caused by storm waves, which move polder. Some parts of the wide foreshore are submerged during flood tide and sediment from the beach to the lower part of the profile (that is, to the deeper, exposed during ebb tide. The polder area further consists of several seasonal underwater parts in front of the beach). After Cyclone Sidr (2007) damaged the and perennial canals/khals, which constitute some fish spawning and nursery forest along the Kuakata coast, the local community found that the erosion of grounds. The depth of the seasonal canals in the polder area is decreasing with the foreshore and the sea beach became more severe. time due to siltation, decreasing the area for sheltering fish juveniles. Local people reported siltation rates of 2 to 3 centimeters per year. Polder 48 falls within the CEIP-1 and improvement works have been applied and are still ongoing. The works specifically include slope protection works together with increasing the crest level of the embankment to protect against Table 6.2: Present and Future Cropping Intensity in Polder 48 SLR and extreme storm surge events, resectioning embankments, afforestation, Polder Present Cropped Area & Future Cropped Cropping replacement of structures, and construction of new structures such as drainage Number Cropping Intensity Area & Cropping Intensity sluices and flushing inlets. Figure 6.10 and Figure 6.11 illustrate the current Intensity Increase works being carried out within the CEIP-I. Cropped Area % Cropped % (%) 2012 (ha) Area (ha) 6.2.2. Coastal Erosion at Kuakata Sea Beach 48 5,836 157 7,095 191 34 The erosion hotspot is located at Kuakata Sea Beach, where a divergence point of the longshore transport is located (Figure 6.12). A divergence point is a Source: World Bank 2021a. location where the net longshore sediment transport equals zero and changes Bangladesh: 200 Enhancing Coastal Resilience in a Changing Climate J. H. Laboyrie Mangrove forest in Polder 48 (February 2020). Figure 6.10: Works undertaken by CEIP-I adjacent to Kuakata Sea Beach direction. At this point, the waves approach the coast perpendicularly. The increasing longshore transport pattern towards the west and east causes a structural retreat of the entire coast. In contrast to this, accretion is observed near the entrances of the tidal rivers at the flanks of the polder where the sediment accumulates, creating sand spits that cause the coastline to advance over time. Satellite imagery of the water line over the last few decades reveals incessant beach erosion in the area at a rate of about 5 to 10 meters per year. The longshore transport is further enhanced by the tide, stimulating transport gradients and local erosion or sedimentation. The erosion trend is expected to persist over the next several decades due to a disequilibrium triggered by a large-scale and long-term reduced sediment inflow and a locally continuous wave and tidal forcing. Much like adjacent coastlines in Bangladesh, the area surrounding Kuakata Sea Beach is (probably) suffering from reduced sediment Slope protection works west of Kuakata Sea Beach. supply from upstream rivers and upstream sediment transport into its nearby estuaries. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 201 Figure 6.11: CEIP-I Interventions in Polder 48 Source: CEIP-I project documents. Bangladesh: 202 Enhancing Coastal Resilience in a Changing Climate Figure 6.12: Yearly Sediment Transport per Transect Considering only the Wave Climate (including tides) during the SW Monsoon Source: World Bank 2021a. Note: Analysis reveals that transport gradients and therefore erosion is largest during the SW monsoon and smaller during the NE monsoon. The coordinate system is Bangladesh Transverse Mercator (BTM) projection with X horizontal and Y vertical in kilometers. 6.2.3. A Hybrid Approach to Combat Coastal Erosion Groynes will keep the beach in place and additional sand nourishments will be added to the outer sides of the groyne-protected area to combat shoreline As an alternative to traditional protection works, a hybrid solution is retreat caused by downdrift erosion. Economic activities can be facilitated by proposed, consisting of both hard and soft measures to maintain an attractive integrating the existing shops, restaurants, and fish markets that are currently sea beach for both locals and tourists. A multifunctional embankment in located along the beach in the multifunctional embankment. Furthermore, combination with groynes and sand nourishments have been proposed to sand nourishments in front of the embankment and between the groynes will combat coastal erosion, reduce the area’s vulnerability to flooding, and allow attract recreational tourism and assist in maintaining the countryside character for the development of tourism and related economic activities (Figure 6.13). of Kuakata (Figure 6.14 and Figure 6.15). Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 203 Figure 6.13: Layout of Proposed Interventions at Polder 48, Kuakata Sea Beach Source: World Bank 2021a. Bangladesh: 204 Enhancing Coastal Resilience in a Changing Climate Figure 6.14: Cross Section of Interventions at Polder 48, Kuakata Sea Beach: Multifunctional Embankment, Sand Nourishment, and Groynes Source: World Bank 2021a. The optimal design of the hybrid solution consists of three groynes in Outside the protected area, the retreat of the shoreline is expected to continue combination with minor sand nourishments. Modeling of the erosion and at a slightly higher pace compared to past decades. As the sub-hotspot of sedimentation patterns of the upcoming two decades shows that, with the Kuakata Sea Beach is located at a divergence point in longshore transport, placement of the three groynes, the shoreline can be stabilized locally. Groynes additional downdrift erosion is predicted to occur on both coastline sections 250 meters long spaced 600 meters apart were found to be effective to block adjacent to the proposed multifunctional embankment; locally up to 10 meters the sediment transport. A possible source for the sediment to be nourished per year. Sand nourishments (with volumes up to 250,000 cubic meters) should could be found east of Polder 48, or from ongoing dredging activities in the be planned for both sides of the beach to mitigate the additional downdrift access channel for Payra Port. erosion for the first 20 years after construction. After a quick reorientation of the beach in the first two years, the area between The hybrid solution can therefore reduce coastal risks by stabilizing the shoreline the groynes will stabilize for the following 20 years. During the first two years at the erosion hotspot, while also providing significant opportunities for after construction, some 30 meters of sedimentation will occur on the western economic growth. A preliminary cost-benefit analysis found a positive benefit- side of the middle groyne, and erosion on the eastern side of the middle cost ratio for the hybrid alternative. As the effects of SLR and the reduced groyne at a similar rate. Also, east of the most western groyne some erosion is probability of damage to critical infrastructure and intangible benefits (such predicted due to shoreline reorientation. Additional nourishments (~110,000 as tourist income, employment, etc.) were not yet included in the preliminary cubic meters) will be needed to counteract the erosion of the western part of analysis, it is strongly believed that the hybrid solution will provide a cost- the beach between the groynes due to the reorientation of the shoreline. After effective alternative for increasing the coastal resilience of Kuakata Sea Beach. this, the area between the groynes will stabilize. The additional benefits are, among others, the revitalization of the Kuakata waterfront, expanded economic opportunities, and increased attractions for tourists (Figure 6.16). Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 205 Figure 6.15: Artist Impression of Kuakata Sea Beach Design for Polder 48 Existing situation Proposed interventions/multifunctional Proposed interventions/groyne field and Potential areas of development after implementation of 1. Kuakata commercial area embankment nourishment interventions (hotels and restaurants) 3. Crest of multifunctional embankment +7.5 m 8. Groyne crest +4 PWD, width 3-5 m, length 250 m, 11. Potential areas for development of tourist activities 2. Main road PWD spacing 600 m 12. Potential areas for development of beachfront tourist 4. Balconies +7.0 m PWD 9. Small-scale sand nourishments to avoid downdrift activities 5. Lower promenade +5.0 m PWD erosion 13. Potential area for development of green areas (afforestation) 6. Beach level +4.0 m PWD 10. Small-scale sand nourishment to advance beach 14. Potential areas for maintenance and development of fishing 7. Road +6.5 m PWD between groynes activities Source: World Bank 2021a. Bangladesh: 206 Enhancing Coastal Resilience in a Changing Climate Figure 6.16: Artist Impression of a Street View, Kuakata Sea Beach Design for Polder 48 Source: World Bank 2021a. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 207 6.3. Cox’s Bazar: A Hybrid, Nature-Based, and Multifunctional which translates to a total of BDT 375 billion yearly. This money circulates in Solution for Combating Coastal Erosion, Preventing Flooding, and the district’s overall economy, creating as many as 2,414,400 jobs in the sector Enhancing Tourism in 2018, a number that was expected to reach 3,155,300 jobs by 2019 (Ahmed 2019). As such, the service sector in Cox’s Bazar (48 percent of the local GDP) 6.3.1. Polder Description, Social Context, and Coastal Dynamics proves the largest when compared with other sectors like agriculture (28 percent) and industry (24 percent) (Lemma et al. 2018). Cox’s Bazar, located in the eastern part of the coastal zone, is the tourism capital of Bangladesh. With property development and an international airport, The Cox’s Bazar-Teknaf Marine Drive Road was built to facilitate tourism Cox’s Bazar could become a billion-dollar income hub for the entire country. opportunities, develop the fishing industry, enhance regional connectivity, The latest developments in security, accommodation, and amusement have and improve the management of natural resources. It is an 80-kilometer-long already prepared the town for hosting local and foreign tourists. At least 500 road that goes from Cox’s Bazar to Teknaf running close to the shoreline. Its hotels, furnished flats, international standard resorts, and restaurants have been construction started in 1993. In June 2008, the first phase of 24 kilometers, from established in the area surrounding the beach. Currently, the number of foreign Kolatali to Inani, was completed. The second phase, which started in July 2008, tourists coming to Bangladesh is small compared to the number of Bangladeshi covered another 24 kilometers of road, from Inani to Shilkhali, and the third outbound tourists; only 267,000 foreign tourists came to Bangladesh in 2018 phase was 32 kilometers from Shilkhali to Teknaf. Construction was completed (Deb and Nafi 2020). However, industry experts say that with improvements in 2018 by the Bangladesh Army, under the supervision of the Bangladesh in infrastructure services and an adequate marketing policy, the number of Roads and Highways Department. The project components include road works, tourists could increase drastically within the next few years. cross drainage structures, and coastline protection works. Cox’s Bazar attracts many domestic tourists. According to local sources, the Over the years, there has been severe erosion and damage to Marine Drive number of domestic tourists rose to 15 million in 2019, from 10 million a year Road, mainly caused by wave action from the sea. The road is directly exposed earlier, with tourists spending an average of BDT 25,000 each in Cox’s Bazar, to the Bay of Bengal and is vulnerable to tides, wave action, and cyclonic storm surges. Since the start of construction, several locations along the road have been damaged by wave action, reducing the width of the beach significantly. To protect these locations, the BWDB suggested protective measures, such as revetments. In some places, combined protection works have been implemented, comprising concrete blocks, tetrapods, and geotubes. Despite working well locally (at some locations the measures caused sedimentation), these measures remain temporary fixes that do not eliminate the need for a more permanent, long-term, solution for the entire road. Tourists at Inani beach, Marine Drive. A view of Cox’s Bazar beach. Bangladesh: 208 Enhancing Coastal Resilience in a Changing Climate J. H. Laboyrie Marine Drive Road at Cox’s Bazar (Himchori Beach), including its current erosion protection measures. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 209 6.3.2. Coastal Erosion Along Marine Drive Road unstable and detach from the river mouth, after which it migrates along the coast, and gradually smooths out. This explains why alternating periods of Satellite imagery shows variations in the erosion and sedimentation in space accretion and erosion occur along this coastline. and time of the coast between Cox’s Bazar and Inani. Several rivers and streams along the coast, of which Raju channel is the largest, deliver water and sediment Over the 30-year period that is covered by satellite imagery, the erosion rates from the hills. The amount is highly variable over time because of heavy rain along Marine Drive Road vary between 3 to 5 meters per year over the long showers during the wet southwest monsoon. Both wave action and cyclones term, and 0 to 10 meters per year over shorter periods. The difference in the add to the variations in the morphodynamics of the system, making this coast short-term versus the long-term rates further substantiates the shoreline sensitive to shoreline instabilities. These shoreline instabilities are likely to be instabilities explained above. Vegetation at the dry beach just in front of the initiated near river mouths, where sand spits occur. During a severe event (such coastal protection measures also indicates that erosive and accretive periods as a cyclone) or if the river breaks through a sand spit, the spit may become alternate. A first order sediment budget estimate based on the average erosion Asif Aminur Rashid Bangladesh: 210 Enhancing Coastal Resilience in a Changing Climate rates at the coast between Cox’s Bazar and Inani shows that typical erosion and Figure 6.17: Location of the Three Sub-Hotspots at Cox’s Bazar and along Ma- sedimentation volumes are in the order of 50,000 to 200,000 cubic meters per rine Drive year. This indicates an important role for sediment input by rivers of at least the same order of magnitude. This case study considered three erosion sub-hotspots: (1) Kolatoli beach; (2) Himchori beach; and (3) Inani beach (Figure 6.17). Kolatoli beach (Figure 6.18 and Figure 6.19) is currently (as of 2020) quite wide, however, satellite images reveal a coastline retreat of about 3 to 5 meters per year. Here, attempts have already been made to combat coastal erosion by constructing small sea walls (Figure 6.19). Himchori beach, on the other hand, is very narrow. Temporary measures have been taken to combat ongoing erosion, including geotubes and tetrapods (Figure 6.20). Inani beach is the widest of all hotspots (Figure 6.21). Here, in the long term, erosion and accretion rates are quite low (0.2 to 1 meter per year), while for shorter time scales, there seems to be fluctuations in the coastline position. Currently, the aforementioned temporary measures work well in providing protection for Marine Drive Road. However, over the long term, more permanent measures will be needed to directly address the cause of the erosion. 6.3.3. A Hybrid Approach to Ensure Coastline Stability A combination of a multifunctional embankment with large sand nourishments is proposed to reduce coastline retreat, minimize the impacts of flooding, and enhance tourism. The embankments would provide the necessary protection against flooding of the hinterland, while the sand nourishments would provide protection against coastal retreat. The proposed multifunctional embankment at Kolatoli (Figure 6.22) and Inani Beach is integrated into the surrounding area and includes space for housing functions such as local shops, restaurants, and (small) hotels. The multifunctional embankment would also aid in further developing the area around Himchori Beach (Figure 6.23) by providing space to locate several additional activities on the embankment. Green slopes with vegetation are included in its design to reduce the impact of waves on the embankment and attract recreational activities. Source: World Bank 2021a. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 211 Figure 6.18: Sub-Hotspot 1: Kolatoli Beach, Cox’s Bazar (during high tide on February 28, 2020) J. H. Laboyrie Source: World Bank 2021a. Figure 6.19: Coastal Protection Structures at Kolatoli Beach J. H. Laboyrie J. H. Laboyrie Short seawall with mild slope and crest accessible by stairs. Short seawall with steep slope. Bangladesh: 212 Enhancing Coastal Resilience in a Changing Climate Figure 6.20: Sub-Hotspot 2: Existing Coastal Protection at Himchori Beach J. H. Laboyrie Birdseye view of coastal protection in Himchori: geotubes, randomly placed tetrapods, and a second series of geotubes along Marine Drive. Source: World Bank 2021a. Figure 6.21: Sub-Hotspot 3: Inani Beach J. H. Laboyrie Source: World Bank 2021a. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 213 The proposed sand nourishments directly mitigate coastline retreat and work Figure 6.22: Cross Section of Proposed Multifunctional Embankment at Kola- well with the existing natural beaches. The three envisaged nourishments at toli Beach each erosion hotspot are intended as a local buffer against ongoing longshore transport of sediment and as a natural sea defense during storms, preventing cross-shore erosion and the undermining of the multifunctional embankments. The sand that is placed at the beaches (and in the underwater section of the profile) would result in a considerable local seaward movement of the coastline, which will erode over time. For every location, a beach width of approximately 100 meters is proposed (Figure 6.24). The nourishment at Inani beach is split into two separate nourishments to avoid blocking the streams that drain water to the sea. Figure 6.25 to Figure 6.30 show further layouts and artist impressions of two of the three beach restoration projects. Source: World Bank 2021a. After construction, the proposed nourishments would quickly change into a Figure 6.23: Cross Section of Proposed Interventions at Himchori Beach bell shape and be dispersed completely after 5 to 10 years at Kolatoli Beach and Himchori Beach, and 10 to 15 years at Inani Beach. The erosion would start at the edges of the nourishment and progress inward over time. These edges coincide with the peaks and troughs in the longshore transport rates. The nourishment at Kolatoli Beach (about 1 million cubic meters) would spread evenly over the coast in about five years, to a width of about 30 meters. The nourishment at Himchori Beach (about 1.4 million cubic meters) would follow a similar pattern, with a width of about 50 meters after five years (Figure 6.31). In comparison, the Inani nourishment (about 0.8 million cubic meters) is expected to evolve considerably slower due to the smaller transport rates locally (Figure Source: World Bank 2021a. 6.32). Here it is recommended to monitor the opening of the streams between Figure 6.24: Cross Section of Sand Nourishment Proposal at Cox’s Bazar and both nourishments and if needed, create new openings if the mouths of the Marine Drive streams are getting blocked by sedimentation. The proposed combination of sand nourishments with a multifunctional embankment will provide the necessary protection of Marine Drive Road while also creating opportunities for local economic development. As the hybrid solution provides protection for both the longshore and cross-shore transport of sand, it will protect the hinterland against both ongoing and event-driven erosion. By continuously monitoring the mobility of the initial nourishments, the ongoing erosion patterns can be better understood. This will make it possible Source: World Bank 2021a. Bangladesh: 214 Enhancing Coastal Resilience in a Changing Climate Figure 6.25: Intervention Layout of Kolatoli Beach with Sand Nourishment and to establish whether additional nourishments are needed to further protect the Multifunctional Embankment area in the long term. Finally, as the area of Cox’s Bazar is known for its sandy beaches, beach restoration through nourishments will benefit the local tourism sector and provide opportunities for economic development. Md. Towshikur Rahman Source: World Bank 2021a. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 215 Figure 6.26: Artist Impression of a Bird’s Eye View of the Design Proposal for Kolatoli Beach Existing situation Proposed interventions/multifunctional embankment Proposed interventions/sand Potential areas of development after 1. Kolatoli commercial area 2. Crest of multifunctional embankment +7.0 m PWD and nourishment implementation of interventions (hotels and restaurants) width 15 m 6. Sand nourishments with a width of 100 m 8. Potential development of tourist 3. Balconies +7.0 m PWD and a length of 1 km activities 4. Lower promenade +5.0 m PWD 7. Beach level +4.0 PWD 9. Potential area for development of 5. Road +6.5 m PWD beachfront tourist activities Source: World Bank 2021a. Bangladesh: 216 Enhancing Coastal Resilience in a Changing Climate Figure 6.27: Street View Perspective of Multifunctional Embankment at Kolatoli Source: World Bank 2021a. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 217 Figure 6.28: Intervention Layout at Himchori Beach: Sand Nourishment and Beautification of Embankment Source: World Bank 2021a. Bangladesh: 218 Enhancing Coastal Resilience in a Changing Climate J. H. Laboyrie Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 219 Figure 6.29: Artist Impression of a Bird’s Eye View of the Design Proposal for Himchori Beach Existing situation Proposed interventions/beautified embankment Proposed interventions/sand Potential areas of development after 1. Himchori hilly area 4. Crest of beautified embankment +5.0 m PWD and nourishment implementation of interventions 2. Existing residential houses width 10 m 7. Sand nourishments with a width of 100 3. Road +6 m PWD 5. Multipurpose shelter for safe development of m and a length of 2 km, Beach level +4.0 8. Potential development of tourist tourist activities PWD activities 6. Green slopes Source: World Bank 2021a. Bangladesh: 220 Enhancing Coastal Resilience in a Changing Climate Figure 6.30: Artist Impression of a Street View of Himchori Beach Source: World Bank 2021a. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 221 Figure 6.31: Nourishment Evolution at Kolatoli Beach (Himchori Beach Shows Figure 6.32: Nourishment Evolution at Inani Beach a Similar Evolution) A few months after construction A few months after construction After 5 years After 1 year After 10 years Source: World Bank 2021a. After 5 years tidal submergence. There are three components of the protective function of mangrove forests: (1) wave attenuation, by mitigation of the hydraulic forces of storm surges; (2) storm protection by providing shelter from the wind; and After 10 years (3) shoreline stabilization as they help with sediment retention and erosion Source: World Bank 2021a. control. Mangroves increase the soil volume as their roots grow and they can capture up to 1,000 tonnes of sediment per square kilometer (Ellison 2000), 6.4.  Opportunities for Integrating Mangroves in Coastal Protection thereby elevating the land. An important precondition for the sediment Strategies capture is that the tidal movement of water in and out of the mangrove forest is not disturbed (such as by embankments or dams placed seawards from 6.4.1. Mangroves in the Coastal Zone the mangroves). One of the best ways to use mangroves to enhance coastal resilience is to protect the existing forest. Protection of existing forests is far Mangroves are forest species located in intertidal zones, commonly seen cheaper and easier than planting new mangrove forests. However, mangrove along the sheltered muddy shorelines of most tropical and a few subtropical loss is continuing worldwide, including in Bangladesh, with conversion to areas (especially deltas) such as the Bengal Delta. Situated between land and aquaculture or agriculture being the most common cause (Thomas et al. 2017). sea, mangrove species are adapted to wet soils, saline habitats, and periodic Bangladesh: 222 Enhancing Coastal Resilience in a Changing Climate In 1966, Bangladesh’s Forest Department launched a program of mangrove timber and land); (4) create employment opportunities in rural communities; (5) afforestation, as the existing Bangladesh Sundarbans mangrove forests create an environment for wildlife, fish, and other estuarine and marine fauna; provided significant protection against cyclone-induced hazards. While the and (6) create forest carbon sequestration opportunities (see Box 6.4). initial objective of the afforestation program was to create a shelter belt to protect the lives and properties of the coastal communities, the success of the Over the last few decades, several cyclones have damaged large portions of plantations further identified additional objectives for coastal afforestation the mangrove forests of the Sundarbans, which have not yet fully recovered. (see Box 6.3), including to: (1) provide forest products for a range of uses; Cyclone Sidr (2007) caused significant damage to the mangroves in the (2) develop forest shelter belts to protect life and property inland from tidal Sundarbans forests, creating a loss of about 10 to 45 percent of the mangroves. surges; (3) inject urgently needed resources into the national economy (that is, The economic loss associated with mangrove degradation by Cyclone Sidr Box 6.3: Ecosystem Services and Livelihoods Benefits from the Sundarbans Mangrove Forest – Opportunities as a Nature-Based Solution Mangroves are among the most productive ecosystems on Earth and are against cyclone and tidal surges originating in the Bay of Bengal, thereby critical in providing a large number of ecosystem services and benefits, reducing the vulnerability to such extreme climatic events (Halder et al. 2021). including protection from flooding, cyclones, and tidal surges; carbon storage The Sundarbans region has experienced more than 20 major cyclones over and sequestration; and support for local livelihoods through the provision of the past two decades, and historically, eight out of the ten deadliest tropical food, fuelwood, timber, and construction materials. As a result of their diverse cyclones have originated in the Bay of Bengal, where the Sundarbans is located. benefits, mangroves are increasingly regarded as a cost-effective nature- based solution. Mangrove ecosystem services are worth US$33,000-57,000 per The latest World Bank The Changing Wealth of Nations: Managing Assets for hectare per year (UNEP 2014). Mangroves can also help fight climate change the Future (2021c) report finds that the mangrove asset value of Bangladesh is and sequester carbon from the atmosphere faster than terrestrial ecosystems, worth about US$10 billion, which is a four-fold increase from their 1995 value. such as tropical rainforests (Donato et al. 2011). A recent estimate suggests that The Sundarbans Forest of Bangladesh provides direct and indirect benefits to global flood protection benefits of mangroves are worth nearly US$65 billion almost 3.5 million people. In the Sundarbans area, forest income contributed per year (Menéndez et al. 2020) and the cyclone protection value of mangroves as much as 74 percent of total household income, mainly through non-timber is worth about US$1.8 million per square kilometer per year (Sun and Carson forest products (Abdullah et al. 2016). The cyclone protection value of the 2020). In Bangladesh, it is estimated that a strip of mangroves 100 meters wide Sundarbans during Cyclone Sidr was valued at about US$1,025 per household can reduce storm surge velocity by up to 92 percent, saving embankment (Akber et al. 2018). The provisioning and cultural ecosystem services from the maintenance costs (Dasgupta et al. 2019). Sundarbans contributed to the revenue of the Bangladesh Forest Department an average of US$744,000 and US$42,000 per year, respectively, with increasing Located on the active delta of the Ganges-Brahmaputra River system, the revenue from the tourism sector (Uddin et al. 2013). Therefore, the prospect of Sundarbans constitute the world’s largest single tract of mangrove forest, utilizing the Bangladesh Sundarbans as a nature-based solution is enormous covering an area of about 10,000 square kilometers (Mukul et al. 2020). This and should be strengthened through scientific management incorporating unique mangrove ecosystem plays an important role by acting as a bio-shield local people’s needs and aspirations. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 223 Box 6.4: Forest Carbon Sequestration Opportunities in Coastal Bangladesh Forests play a crucial role in the global carbon cycle, and increasing emphasis Figure 6.33: Carbon Stock Densities in the Major Pools by the Forest Zones of is now put on forestry activities, including forest and landscape restoration, as Bangladesh an effective tool for climate change mitigation (Houghton 2013). Forests can reduce GHG from the atmosphere in two ways: (1) by avoiding emissions from deforestation and degradation; and (2) by letting them grow to sequester more carbon from the atmosphere. Forest carbon can be stored in five different pools: (1) aboveground biomass; (2) belowground biomass; (3) litter; (4) deadwood/ woody debris; and (5) soil (Mukul, Halim, and Herbohn 2021). However, the capacity of different forests to sequester carbon varies. Tropical mangrove forests, for example, have a higher carbon density than tropical rainforests, and they are also highly regarded for their capacity to sequester carbon faster than any other terrestrial ecosystem (Donato et al. 2011). Source: GoB 2020. About 20 percent of Bangladesh’s GHG emissions are estimated to derive Note: CLitter – carbon in litter; CDB – carbon in dead biomass; CBGB – carbon in from land-use, land-use change, and forestry activities, although the country’s belowground biomass; CAGB – carbon in aboveground biomass; SOC – soil organic carbon for 0-30 cm depth soil layer and 30-100 cm depth soil layer. contribution to global GHG emissions is rather low. Per capita CO2 emissions are also low and were estimated at 0.51 metric tons in 2018 (World Bank 2021b). (Mukul et al. 2014). Over the past few decades, the quality and extent of forests have deteriorated in most parts of the country. Given the high population According to the latest Bangladesh National Forest Inventory, forest areas pressure and high demand for land for competing uses, extending forest hold 21.5 percent of the total carbon stock in the country (GoB 2020). A cover in most parts of the country is quite difficult. The coastal regions of the large variability exists, however, in the national-level estimates of forest country can be effectively used for this, where plantations under social forestry carbon density, which is mainly attributable to differences in methods and arrangements can be raised for carbon sequestration, coastal protection, and sampling strategies (Mukul et al. 2014). The density of carbon in aboveground, local livelihoods benefits. Restoration of degraded mangrove and other forests belowground, and dead biomass is highest in the Sundarbans mangrove forest using suitable species and coastal land stabilization for soil carbon benefits are followed by coastal mangrove plantations (Figure 6.33). Carbon density in also crucial. belowground biomass is 9.6 times higher in the Sundarbans compared to the national average. Nationally, most of the carbon stock is contained in the top Global forest carbon credits are valued at over US$100 billion per year and 30 centimeters of soil (80 percent), followed by the aboveground biomass (15 are an emerging, growing sector. Tackling deforestation is the cheapest option percent). In the Sundarbans and coastal mangrove plantations, the soil carbon for reducing human-induced GHG emissions, and thereby addressing climate density at a 100-centimeter depth is more than double that at a 30-centimeter change. To fully capture this opportunity, the carbon sequestration potential of depth. Bangladesh’s forestry sector needs to integrate a high-quality forest monitoring and reporting mechanism with REDD+ (Reducing Emissions from Deforestation The spatial distribution of forests is not uniform across the country, they are and Forest Degradation) and other voluntary carbon payment schemes. scattered mainly in the few districts of southern, central, and coastal Bangladesh Bangladesh: 224 Enhancing Coastal Resilience in a Changing Climate alone was estimated to be approximately US$142.9 million (Khan et al. 2021). After Cyclone Figure 6.34: Spatial Distribution of Damage (percentage Sidr, subsequent storms (Figure 6.34) continued to damage the mangrove forests, which is why of area disturbed) Caused by Three Tropical Cyclones Bangladesh is looking into active interventions for restoration. While restoration and afforestation (SIDR, Rashmi, and Aila) Affecting the Sundarbans from are not always needed to recover mangrove forests, natural recovery takes time. As of 2018, about 2007 to 2009 48 percent of the areas affected by Cyclone Sidr had not yet recovered, highlighting the need for active interventions. 6.4.2. Restoration of Mangrove Forests for Coastal Protection Mangrove forests can be restored for coastal protection purposes (for wave attenuation and surge velocity reduction), for their ecological functions (such as being a breeding and nursery habitat) and/or for economic reasons (such as wood harvesting). Defining the specific aim of the restoration effort is an important first step in the design of an afforestation project since the type of mangrove and the required size of the forest varies by function. Different mangrove restoration techniques (Figure 6.35) could be implemented depending on the reason for the lack of mangroves. In this case study, mangrove afforestation for coastal protection purposes, specifically wave attenuation, was considered. The effectiveness of mangroves for wave attenuation is assessed by evaluating their impact on required embankment heights. A mangrove belt of a few hundred meters will have a small impact on the surge height, but can significantly reduce wave run-up, and with that, the amount of overtopping over an embankment. Wave attenuation rates range from 5 to 100 percent over 100 meters of mangrove forest (Figure 6.36), depending on incoming wave heights and periods, but also as a function of the tree species, tree geometry, and total vegetation extent (Mazda et al. 1997; Bao et al. 2011). Assuming a conservative wave height reduction of 8 percent over 100 meters of mangroves, and a mangrove belt of 500 meters, a 40 percent reduction of the wave height could be the result. By reevaluating the crest height of the embankment based on the design overtopping volume (5 liters per meter per second) for Polder 56/57, such a mangrove forest would reduce the required crest height of the embankment by almost 10 percent (from 6.1 meters to 5.5 meters) (Figure 6.37). This reduction in crest height would decrease the direct costs of raising the embankment and reduce the required footprint of the embankment, and thus the indirect costs in the polder itself (such as for land acquisition). Ultimately, the wave attenuation obtained from a mangrove belt depends on the bathymetry, the characteristics of the planted (or native) mangrove species, and the local wave climate. Furthermore, Source: Kraus and Osland 2019. Note: Red-dashed arrows indicate approximate storm tracks. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 225 Figure 6.35: Illustration of Several Mangrove Restoration Techniques Figure 6.36: Wave Reduction through a 100 m-wide Mangrove Belt, Depen- dent on Incoming Wave Height and Periods Source: Gijón Mancheño et al. 2021. Source: Gijón Mancheño et al. 2021. Bangladesh: 226 Enhancing Coastal Resilience in a Changing Climate Figure 6.37: Design Water Levels (left) and Required Embankment Height (right) with and without Wave Attenuation by a Mangrove Belt (Polder 56/57) Source: Gijón Mancheño et al. 2021. the effectiveness of a combination of mangrove forests in front of embankments indicator of suitability as mangrove habitat and suggests that there is a natural also strongly depends on the local morphological conditions. This can be supply of seeds. Secondly, the selected stretches were classified as accreting analyzed using a hydrodynamic model that includes the effect of the vegetation (expanding seaward) or eroding (retreating landward), to determine which and evaluates if and how the bathymetry (and the rate of wave attenuation) will type of afforestation methods would be needed. “Natural colonization” and change over time. To identify locations for mangrove afforestation, the current “Planting” approaches (Figure 6.35) could be suitable afforestation techniques and expected future wave climates (influenced by interventions and climate in accreting sections, while erosion mitigation measures would also be needed change) and resulting sedimentological conditions must be analyzed carefully. at eroding sites. Lastly, afforestation was prioritized seawards from the polder areas with the lowest ground elevation, as these are most at risk from flooding. 6.4.3. Potential Sites for Mangrove Restoration and Afforestation The steps to identify potential sites for mangrove afforestation are illustrated in Figure 6.38. Analyses of the conditions necessary for mangrove growth have helped identify potential mangrove habitats in Bangladesh’s coastal zone. Information from Several mangrove afforestation locations with high potential and priority satellite imagery was used (Gijón Mancheño et al. 2021). Firstly, sites within 10 (in terms of flood risk) were thus identified in Bangladesh (Figure 6.3926 ). kilometers of existing mangrove forests were selected along the coastline (10 These sites are highlighted in green if the coastline is expanding and orange kilometers being the distance needed for colonization based on the dispersal if the coastline is eroding (in that case the sites would need more detailed distance of mangroves). A nearby mangrove presence is considered an assessments, and investments in erosion mitigation techniques). While natural Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 227 Figure 6.38: Steps to Find Potential Sites for Mangrove Afforestation Figure 6.39: Mangrove Establishment Opportunities Along the Coastline of Bangladesh Source: Gijón Mancheño et al. 2021. Source: Gijón Mancheño et al. 2021. Note: Existing mangroves are shown in dark green, and new potential afforestation sites are enclosed by black rectangles. The coastline is highlighted in light green at locations where it is expanding (moving seawards) and in orange at locations where it is retreating (moving landwards). Natural colonization and planting are possible afforestation techniques at expanding locations, whereas erosion mitigation measures are needed at eroding sites. colonization (if there is seedling availability in the area) is likely to take place in in the Meghna Estuary and along the eastern shoreline. The sites in the Meghna multiple locations indicated in green (such as at Barguna and Patuakhali, Bhola Estuary have potential to help reduce flood risk and can benefit from easy and Noakhali, along the coastline of Chandnandi, and at Cox’s Bazar), planting restoration on accreting lands, although for other places (such as Bhola island), must be considered if natural colonization is too slow for coastal protection mangrove restoration should be combined with erosion mitigation measures. purposes. In total, approximately 600 kilometers of coastal stretches are The east coast locations are close to existing mangrove forests, making natural located within 10 kilometers of existing mangrove patches. Multiple potential recruitment or planting relatively easy. restoration locations were identified (enclosed by black boxes), mostly centered Bangladesh: 228 Enhancing Coastal Resilience in a Changing Climate The analysis shows that a significant area in the coastal zone has the potential and local communities. This mapping exercise provides a systematic insight into for mangrove afforestation. Mangroves could be a low-cost alternative to where potential opportunities of combined solutions that include mangroves hard flood and riverbank erosion protection works. Also, mangroves can are possible along the entire coastal zone. This is vital input for enhancing be combined with embankments to lower the required elevation (and thus combinations of green and grey infrastructure in the planning and programming footprint) of the embankments. The fact that mangroves require little O&M of future investments in the coastal zone. The mapping methodology could could be a considerable advantage considering the O&M challenges in also be applicable for projects in other countries, while lessons learned from Bangladesh’s coastal zone. Also, mangrove afforestation programs could projects elsewhere can help identify best practices for the development of such help restore damaged ecosystems, benefiting both the natural environment a project in Bangladesh (Box 6.5). Swarna Kazi Box 6.5: Mangrove Afforestation in Indonesia Indonesia has 23 percent of the mangrove areas in the world, and the greatest mechanism. The project aimed to stop this retreat and create new habitat for richness in terms of mangrove species. However, it also has one of the mangrove colonization, while providing economic alternatives for the local highest mangrove deforestation rates, having lost 40 percent of its forests to communities. aquaculture over the last three decades. Mangrove loss has exposed coastal areas to the effects of extreme events and RSLR. By restoring mangroves, Figure 6.40: (a) Ground Elevation of Java (Indonesia); (b) Map of Mangrove Presence in Indonesia vulnerable coastal communities can increase their resilience and recover these natural flood defenses. The methodology to identify potential mangrove afforestation sites presented in Section 6.4. could also help highlight sites with high mangrove suitability in Indonesia. In order to provide an indication of its mangrove potential, the mangrove cover, ground elevation, and shoreline behavior data of Java, the most populated island in Indonesia, are shown in Figure 6.40. The north coastline of Java is shallower and has more areas exposed to large coastline retreat compared to the south. Moreover, several urban areas along the north coast experience land subsidence due to groundwater extraction. However, Java also has regions with considerable mangrove presence, such as the area east of Jakarta, and the areas of Indramayu, Semarang, Surabaya, and Pasuruan. The specific sites to be restored could be assessed resorting to more detailed flood risk and infrastructure data, in combination with the ground elevation and shoreline behavior data shown in the figure above. Since the island of Java is densely populated, mangrove restoration at these sites has a large potential for flood risk reduction. The Building with Nature Indonesia project was carried out between 2014- 2020 with the aim to restore mangroves along the eroding coastline of Demak, Source: Elevation and shoreline data: https://blueearthdata.org; mangrove cover data: https://globalforestwatch.org. in north Java. Mangrove deforestation in combination with land subsidence Note: The ground elevation is shown, with dark green corresponding to lower ground due to groundwater extraction had caused coastline retreat rates of up to 100 elevations and yellow and brown corresponding to higher ground elevations. The meters per year in Demak. The loss of mangrove vegetation left coastal areas behavior of the shoreline is shown by dots, with light green dots corresponding to expanding coastlines (moving seawards) and pink dots corresponding to eroding exposed to the effect of waves and removed their natural sediment trapping coastlines (moving landwards). Bangladesh: 230 Enhancing Coastal Resilience in a Changing Climate 6.5. Notes Bamboo and brushwood structures were built along the coastal system to attenuate waves and enhance sediment trapping near the 24. More information on multifunctional embankments is available at: https://www. flooddefences.org. shoreline. This accumulation of sediment provided new ground for mangrove establishment. The project also included a line of research 25. Bogi is a village in Polder 35/1 in Southkhali Union, Sharankhola Upazila, Bagerhat on sustainable aquaculture techniques, to develop farming techniques District. that were compatible with the protection of the mangrove forest. The project was developed in collaboration between the local communities, 26. A full description of the methodology and detailed maps showing mangrove afforestation opportunities can be found in the following article: https://www.mdpi. nongovernmental organizations (NGOs), research institutes, and com/2071-1050/13/15/8212. engineering companies (for further information see: https://www. ecoshape.org/en/pilots/building-with-nature-indonesia/). 6.6. References Abdullah, A. N. M., N. Stacey, S. T. Garnett, and B. 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Cambridge, UK: United Nations Environment Programme and World Conservation Monitoring Centre. World Bank. 2021a. “Technical Assistance on Developing Concept Design Solutions for Coastal Erosion in Bangladesh.” (Consultant Firms: CDR, Deltares, IWM). World Bank. 2021b. World Development Indicators: Bangladesh. Available at: https://data.worldbank.org/ indicator/EN.ATM.CO2E.PC?end=2018&locations=BD&start=1960&view=chart. Accessed October 30, 2021. World Bank. 2021c. The Changing Wealth of Nations: Managing Assets for the Future. Washington DC: The World Bank. Chapter 6: Building with Nature: Innovative Solutions for Coastal Resilience 233 A WAY FORWARD: SEVEN RECOMMENDATIONS FOR A MORE RESILIENT COAST 7.1. Recommendation 1: Strengthen O&M to extract maximum benefits from investments and nurture sustainable interventions 7.2. Recommendation 2: Embrace the uniqueness of the Bangladesh coast, recognize local knowledge, strengthen the application of state-of-the-art modeling tools and systems, and cultivate knowledge sharing 7.3. Recommendation 3: Apply risk as the guiding principle for adaptative delta management 7.4. Recommendation 4: Complement infrastructure interventions with nature-based solutions to enhance resilience and effectiveness 7.5. Recommendation 5: Incorporate risk-sensitive land-use planning to guide appropriate activities based on integrated coastal zone management practices 7.6. Recommendation 6: Support inclusive community participation, local institutions, and livelihoods adaptation for sustainable resilience 7.7. Recommendation 7: Establish an integrated framework of performance criteria of interventions that goes beyond risk reduction and includes growth, wellbeing, and sustainable development at its core 7.8. Coastal Resilience will Support Delta Prosperity 7.9. Notes 7.10. References Bangladesh: 234 Enhancing Coastal Resilience in a Changing Climate Mahfuzul Hasan Bhuiyan CHAPTER 7: A WAY FORWARD: SEVEN RECOMMENDATIONS FOR A MORE RESILIENT COAST So far, this report has shown that Bangladesh has already made significant emergencies and enhance the resilience of local communities. The country has steps in enhancing coastal resilience and many achievements and milestones implemented structural interventions, such as constructing and strengthening illustrate this. Addressing climate change and improving the resilience of the river embankments and coastal polders, building multipurpose disaster coastal zone is a national priority for Bangladesh; since Independence, the shelters and resilient houses, adapting rural households’ farming systems to country has invested more than US$10 billion (Government of Bangladesh better cope with environmental stressors, and taking measures to reduce saline 2018) in climate resilience actions. An investment portfolio of a wide variety of water intrusion (such as building water management infrastructure). These structural and non-structural interventions has been implemented, alongside have been complemented with a variety of non-structural measures such as efforts to increase the capacity of government agencies to respond to strengthening hydrometeorological services, implementing EWS, awareness- Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 235 raising systems, emergency management systems, and enhancing community- This chapter explores seven key recommendations (listed below) to move based disaster preparedness programs. Altogether, these investments have towards a more resilient coast. They are as specific as possible, grounded in the significantly reduced damages and losses from extreme events over the years, work presented in this report and based on global best practices, with strategic especially in terms of deaths and injuries. In Chapter 4, a detailed evaluation of actions proposed for implementation of each recommendation. the effectiveness of some of these interventions is provided. 1. Strengthen O&M to extract maximum benefits from investments and Bangladesh’s ambition to become an upper middle-income country by 2030 is nurture sustainable interventions. subject to significant challenges; alongside rapid socioeconomic development 2. Embrace the uniqueness of the Bangladesh coast, recognize local there are increasing adverse impacts from climate change. A recent report knowledge, strengthen the application of state-of-the art modeling tools (PwC 2017) forecasts that Bangladesh will become the 23rd largest economy and systems, and cultivate knowledge sharing. in the world by 2050, advancing from 41st place in 2020, as a result of steady 3. Apply risk as the guiding principle for adaptive delta management. projected economic growth. The time frame of this economic transition, 4. Complement infrastructure interventions with nature-based solutions to however, coincides with a rapidly changing climate and its associated potential enhance resilience and effectiveness. increase in the intensity and frequency of climate-induced disasters, expected 5. Incorporate risk-sensitive land-use planning to guide appropriate activities rapid urbanization, loss of agricultural land, uncertainty in water availability based on integrated coastal zone management practices. from upstream, and an accelerated rise in sea levels along the coast. This could 6. Support inclusive community participation, local institutions, and livelihoods all result in more frequent floods, permanent inundation, increased salinity, and adaptation for sustainable resilience. changing sediment dynamics. Therefore, to achieve Bangladesh’s aspiration to 7. Establish an integrated framework of performance criteria of interventions become a safe, sustainable, and resilient delta, specific medium- and long- that goes beyond risk reduction and includes growth, wellbeing, and term goals have been set to ensure protection from the devastating impacts sustainable development at its core. of climate change, build an integrated and sustainable estuary management strategy, preserve and properly utilize valuable ecosystems, and ensure an optimum level of integrated use of land and water resources. J. H. Laboyrie Bangladesh: 236 Enhancing Coastal Resilience in a Changing Climate CHAPTER 7 02 7.1. Recommendation 1: Strengthen O&M to extract maximum and non-cyclone situations. Global examples show that good O&M will pay off benefits from investments and nurture sustainable interventions in several ways, including adequate functioning of the assets, postponement of large rehabilitation works, and the ability to be more proactive in the planning Key message: Solid O&M of all existing natural and human-made structural and implementation of asset upgrades. “Getting the basics right” is crucial to and non-structural assets (that is, forests, embankments, drainage systems, reaping these benefits. At least three limiting factors were derived from the shelters, EWS) is the foundation of coastal resilience. Investments in O&M evaluation of past projects in Chapter 4 and other reviews, for which specific activities alongside clear organizational responsibilities should be prioritized recommendations have been formulated to help overcome them. to ensure that existing key assets provide their essential services to coastal communities. First, Bangladesh needs to shift its trajectory towards ensuring that assets reach their intended lifetime by implementing sound O&M practices. This reduces the The coast of Bangladesh has a vast and varied system of natural and human- need for ad hoc infrastructure investments and enables the country to move made structural and non-structural assets providing essential services to away from a mindset of “build, neglect, rebuild” towards more sustainable and coastal communities, such as flood and erosion protection, and livelihoods long-term solutions. Proper O&M of assets is often limited because of budgetary opportunities. Examples of these systems are tidal river and coastal ecosystems constraints in Bangladesh. Insufficient funding for O&M is a major concern and (for example, forests, embankments, polder drainage systems, riverbank has complex social, institutional, and financial dimensions. For example, the protection works, shelters, and EWS. On the one hand, the Bengal delta system, BWDB, the main authority in Bangladesh responsible for water management with its abundant sediment and mangroves, is part of the largest natural infrastructure (such as embankments, drainage sluices, and canals), does delta ecosystem in the world. On the other hand, it has extensive human- not have sufficient budget or manpower to carry out proper monitoring of made systems: over 6,000 kilometers of embankments, approximately 5,000 the polders; often only a small fraction of the actual required O&M budget multipurpose disaster shelters, 8,000 kilometers of canals, more than 2,000 is approved. In the past, inadequate O&M has led to damaged hydraulic drainage/flushing structures, and 1,000 regulators (see Chapter 2 for more structures, deteriorating embankments, and the silting up of drainage canals, details). leading to reduced operability and reliability of these infrastructure systems. The lack of funding for O&M leads to the approach of implementing temporary Good O&M of all these assets is the foundation for coastal resilience, but as in and emergency protection works in locations where a failure or breach has many places around the world, sound O&M is challenging. In Bangladesh, the been identified after extreme conditions. The impact of Super Cyclone Amphan O&M activities vary depending on the asset category, with each having their (May 2020) is a recent example of the application of such temporary emergency own distinctive characteristics. For example, the maintenance of embankment protection works, which were used in locations where the impacts of erosion systems requires regular checks to ensure that design dimensions (such as were significant and the stability of the previously implemented emergency height or width) are maintained, and the embankments are in acceptable works required further strengthening given the cyclone event. Had there been condition, and to identify any deviations from the original design that need sufficient investments in the needed protection works and adequate O&M, maintenance (e.g. emerging cracks). Regular maintenance activities of human- such ad hoc emergency works may not have been required. A global analysis made structures include grass cutting and cleaning, while post-disaster event highlighted that poor maintenance could increase the infrastructure investment activities often consist of repairs to damaged roofs or bank protection works. needs by 50 to 60 percent for transport and water infrastructure (Hallegatte, From an operational perspective, activities include the opening and closing Rentschler, and Rozenberg 2019), while in the United Kingdom, it was found of drainage/flushing structures or the management of shelters during cyclone that every dollar spent on the maintenance of flood protection works limits Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 237 capital expenditure by seven dollars (JBA 2021). Given the size of investments activities should not take a solely top-down approach but should actively in Bangladesh, these benefits could be substantial and would free up capital involve local communities throughout the O&M cycle. Local communities for alternative investments. often have better knowledge of the local conditions, which is essential for the O&M process. Good initiatives to enhance community participation in O&M Second, technological advances should be embraced to systematically monitor have been piloted by projects such as the CEIP-I and the Blue Gold Program. the vast number of assets in the coastal zone. Systematic monitoring of asset For example, the CEIP-I is implementing a participatory scheme for O&M data for O&M and establishing detailed O&M procedures is another challenge management, by involving local communities at all stages of project planning, in Bangladesh. Up-to-date knowledge of the status of the assets is the premise implementation, and monitoring (see Chapter 4). WMOs have engaged women for planning O&M activities and identifying the human and financial resources in their communities as members as well as in leadership positions to improve required to perform such O&M activities. A review of past projects in Chapter the uptake of good O&M practices across gender and social groups. As per the 4 showed that systematic monitoring of coastal protection works is often national Participatory Water Management Rules, women must form 30 percent not in place. However, this monitoring is essential to move away from ad of the WMO constituency, and should be given encouragement to join WMOs hoc emergency works and to be able to plan for regular maintenance and and be provided with training on gender and leadership. Such initiatives can be the potential upgrading of assets. As an example, within the recent CEIP-I, all further upscaled and mainstreamed into other O&M initiatives. available information on embankments and structures for the entire polder system is being collected and stored in one geoportal for relevant stakeholders Strengthening these O&M factors is an essential first step in enhancing to access (with the necessary approvals). Similar databases should be coastal resilience to safeguard the functionality of existing natural and developed for other structural and non-structural assets in the coastal zone in human-made assets and to ensure that investments in assets will continue to collaboration with the relevant asset owners. Technology can help in monitoring provide the essential services throughout their envisioned lifetime. Specific a large number of assets, for instance using satellite imagery to detect trends recommendations to enhance O&M in Bangladesh are to: in forest cover, InSAR satellites to detect ground displacement around assets, and remote sensing to detect riverbank erosion. This can help in continuously • Allocate more funding for O&M alongside exploring new revenue streams monitoring assets in space and time and can provide the necessary information for financing O&M. The BDP 2100 recommends that 0.5 percent of GDP be to determine where to prioritize in-depth O&M inspections. On top of that, allocated for the O&M of water management infrastructure. The present budget and staffing should be appropriated to manage these data systems level of the O&M budget is estimated to be about 0.1 percent of GDP. continuously. In addition, an O&M planning system should be set up to decide These resources are required to increase staffing, develop systematic when (and where) appropriate actions need to be taken. management systems, and provide funding for regular maintenance activities. A thorough analysis of existing O&M funding and how it is Lastly, local involvement in O&M activities should be fostered and embraced currently spent is necessary, which can help set specific recommendations in large-scale infrastructure investments. Historically, O&M was mainly on how to increase and make better use of this budget carried out by the responsible agency, although it was often limited because of budget constraints, and did not incorporate forward-looking practices • Further strengthen the use of technology, tools, and data for solid asset regarding monitoring and O&M procedures. As outlined above, adequate management and embed these systems in the O&M organization of the resources, staffing, and implementation of good practices will improve the relevant agencies. Existing database systems, such as the disaster shelter current O&M activities of these agencies. However, the organization of O&M database maintained by the LGED and the initiative now under development Bangladesh: 238 Enhancing Coastal Resilience in a Changing Climate within the CEIP-I for the entire polder system, could be a good starting • Enhance the governance structure of structural assets with further point for an asset management system of the BWDB and enhancement of streamlining and upscaling of community involvement and engagement. mangrove mapping and management for Bangladesh Forest Department. Project initiatives should be developed to ensure continuity after project The use of recent advances in technology, in particular remote sensing, lifetimes, with clearly defined roles and responsibilities, and funding should be incorporated into O&M as it can provide a low-cost solution sources for O&M for local communities. for monitoring a large number of assets in space and time, and aid in the prioritization of in-depth inspections. Ismail Ferdous Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 239 7.2. Recommendation 2: Embrace the uniqueness of the Bangladesh coastal structures such as embankments and drainage structures (see Chapter coast, recognize local knowledge, strengthen the application 3). The dynamic tidal riverbanks change as a result of tidal motion, waves, and of state-of-the-art modeling tools and systems, and cultivate seasonally varying river discharge and sediment supply. To date, however, the knowledge sharing understanding of and predictive capability about this phenomenon is limited in Bangladesh and in practice, bank erosion needs are mainly based only on Key message: In-depth knowledge of the coast and the interaction with experts’ judgement—the use of tools and models can provide complementary the structural interventions is another foundation for coastal resilience. The information to better guide planning. SLR, changes in cyclone intensity, and unique landscape and dynamics of coastal Bangladesh requires a thorough shifts in the fresh water and sediment supply from upstream play an important understanding of how the present system functions and its inherent uncertainties role in longer time scales and will add to the complexity of predicting system in order to predict how future scenarios of the coastal environmental conditions behavior in the future. might change the system as a whole and what that means in terms of the design of interventions. Continuous development of knowledge and the application of Bangladesh has successfully built up a knowledge base of the coastal system, state-of-the-art tools and guidelines should be prioritized, including knowledge resulting in more resilience for its communities. A good example is the transfer of these developments. development and implementation of community based EWS in Bangladesh (see Chapter 4). An integrated approach consisting of coastal embankments The coastal landscape of Bangladesh is predominantly shaped by the GBM as a first line of defense, complemented by advanced cyclone forecasting, river systems that drain an enormous amount of water and sediment from sufficient warning of the local communities, and a network of cyclone shelters the Himalayan Mountain range into the Bay of Bengal, with tides and waves and access roads along with a systematic mobilization of volunteers to conduct redistributing this sediment along the coast. The interactions between the cyclone preparedness and awareness-raising campaigns, has resulted in a steep sediment, fresh and saline water, and underlying geology of the area provide decrease in the number of casualties in the coastal zone over the past couple of the building blocks for the unique delta landscape and its productive, diverse, decades. This would not have been possible without the development of data and dynamic ecosystems that are host to an abundance of flora and fauna. For and modeling tools to better predict cyclone characteristics in advance and instance, while the western and central parts of the coastal zone are low-lying during landfall. These knowledge and modeling capabilities are also embedded with numerous tidal channels and creeks, the southeast has steep topography in various research institutes and universities in Bangladesh. The successful with small rivers draining from the hills. Refer to Chapter 2 for an extensive application of knowledge to increase resilience should inspire the relevant overview of the coastal landscape and its characteristics. stakeholders to further intensify investments in knowledge development. Three areas of attention are specifically highlighted based on the presented analytics. Given the uniqueness of the Bangladesh coastal zone, local knowledge and research is essential for sustainable coastal zone management, which can also First, systematic data collection, storage, and analysis of the natural add to the knowledge base of delta dynamics globally. Understanding the key environment, including monitoring for changes in the system, should be processes that shape the system dynamics is critical to the ability to predict prioritized. Essential physical, chemical, and biological data to be collected changes in the system in the near and long-term future, especially in view of are, among others, bathymetry, water levels, waves, currents, river discharge, climate change. Tidal riverbank erosion is a practical example of why insights salinity, temperature, sediment concentration, sediment grain size distribution, into coastal system behavior are a necessity for management purposes. This nutrients, and heavy metals. Remote sensing data is an additional powerful phenomenon results in the loss of valuable land and undermines the integrity of data source for understanding coastal systems. For example, recent research Bangladesh: 240 Enhancing Coastal Resilience in a Changing Climate has demonstrated that large-scale analysis of bank movements from space is Second, numerical models should be treated in a similar way as data collection, now feasible (Jarriel et al. 2020). The collection and analysis of satellite imagery meaning that they should be continuously developed and applied in practice as can thus complement ground observations to better understand the spatial part of the overall management of the system rather than on a project-specific movement of riverbanks. Currently, such data sources are often collected as basis only. In the past, a variety of numerical models have been developed part of individual projects but are not collected in a systematic way. As outlined for the coast of Bangladesh, often as part of large investment projects. For above, changes in the system often happen at multiple scales both spatially and example, various one-dimensional models have been set up describing temporally. A systematic and continuous system-wide survey and monitoring the distribution of water flows in the Bangladesh delta. The next step is to system will help detect trends and anomalies at the various spatial and temporal develop, maintain, and apply a structured hierarchy of numerical models to scales, which can complement modeling studies and help identify drivers of cover all spatial and temporal scales of the system, including regarding the change. hydrodynamic, sediment, morphological, and ecological behavior of the system. There are now innovative modeling techniques available to achieve a Asif Aminur Rashid Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 241 BANGLADESH COASTAL RESILIENCE 03 much higher spatial and temporal resolution, providing much more detail on • Expand and intensify coastal monitoring through more systematic the governing physical and ecological processes, resulting in a more accurate collection, storage, and analysis of relevant ground observations and representation of reality. Both ground and remotely sensed observations are remote-sensing data. The data should be updated and maintained via essential ingredients feeding into these numerical models in order to generate a data sharing platform within the government and also with the wider and update model schematizations and validate the model outputs. public, with necessary protocols established. Third, open data sharing platforms should be established to make knowledge • Develop and maintain a hierarchy of flow and sediment models with high widely available and allow consistent use of input parameters and scenarios resolution for the coastal zone to better predict changes in the system across projects. Knowledge transfer and data sharing between agencies but (such as storm surge levels, waves, bank erosion, large-scale erosion, and also with the public are essential ingredients for successful cooperation within sedimentation patterns). These models should be coupled with observed government and to help create awareness among and inform the general public. data and continuously finetuned and adopted for practical applications to The data needed for coastal resilience interventions are multidimensional, with improve EWS, and the design and maintenance of interventions. data variables covering the natural environment, local economy, and social- demographic characteristics. Although such data is often collected for specific • Create a better knowledge sharing and training environment for young projects, data sharing mechanisms are not always in place, or need extensive professionals in collaboration with universities. The data sharing and knowledge transfer. As such, collective data platforms, such as the Geospatial modeling initiatives can be the basis of this collaboration. This could be Data Sharing Platform (known as GeoDash),27 are essential to ensure that the further stimulated by defining regular challenges for students around most up-to-date and accurate resources are used in projects. The inclusion of coastal topics and/or creating positions for students to join ongoing readable and clear metadata is key for reproducibility and for understanding programs and bring in innovative ideas and applications of state-of-the- the underlying model assumptions or data limitations associated with a dataset. art knowledge. Effective data sharing can free up resources and facilitate dialogue between stakeholders. Universities and research institutes are key stakeholders in this. The current Long-Term Monitoring and Research Program within the CEIP-I is Apart from data sharing and knowledge transfer, it is essential to maintain the an ideal catalyst for making progress in this field of knowledge development consistency of certain key variables (such as the expected rate of SLR) and and numerical tools (see Box 7.1). This initiative has already collected a scenarios (such as future socioeconomic scenarios) across projects. In some large amount of system data, generated a hierarchy of models, and provided cases, inconsistencies are present within different projects, which can result in recommendations on improving design guidelines. It is recommended that regional discrepancies in terms of project outcomes. Therefore, it is important the relevant agencies (in this case the BWDB) take the results of this program to create consistent baseline variables and future scenarios across projects. forward to ensure that dedicated personnel within the organization can further Within the CEIP-I’s Long-Term Monitoring and Research Program, for instance, develop and adopt this knowledge and the numerical tools for management consistent climate change scenarios are prescribed for the different polders applications. With the support of this knowledge and the associated tools, based on various model outcomes and assumptions. proactive planning of interventions, optimization of designs, and improved maintenance are within reach, resulting in more efficient use of available Enhancing in-depth knowledge and embedding the use of state-of-the-art budgets. tools and scenarios into the planning and design of coastal interventions is paramount for Bangladesh. Specific recommendations are to: Bangladesh: 242 Enhancing Coastal Resilience in a Changing Climate Box 7.1: Progress within the CEIP-I Long-Term Monitoring and 7.3. Recommendation 3: Apply risk as the guiding principle for Research Program adaptative delta management The dynamic coast of Bangladesh is subject to a multitude of complex natural Key message: Given the changing climate and dynamic coastal processes of phenomena, human intervention, and climate change, most of which are not yet Bangladesh’s coastal zone, ADM should be the cornerstone of any approach to well understood. In addition, there is limited systematic monitoring of the coastal achieving coastal resilience. ADM is about flexible decision-making in view of the region, which is needed to generate data, information, and new knowledge to uncertainties related to present and future risks. International experience shows assess the effects of the multiple drivers on the coastal environment to guide that a risk management approach is well suited for informing decisions about future design, rehabilitation, and improvement of investment requirements. public safety given large uncertainties. Adopting such a risk-based approach could help tie together strategic planning, design, and O&M, further improving To bridge this knowledge gap, the CEIP-I is supporting a comprehensive monitoring and morphological assessment of the Bangladesh Delta, known the efficiency and effectiveness of coastal interventions in Bangladesh. as the Long-Term Monitoring, Research and Analysis of Bangladesh Coastal Zone (Sustainable Polders Adapted to Coastal Dynamics) Program. Through Past disruptive catastrophic events such as Cyclones Bhola (1970), Gorky this initiative, the CEIP-I is developing a framework for polder design and an (1991), and Sidr (2007) have highlighted the vulnerability of the coast and its investment plan based on an improved understanding of, and new insights communities. These events have caused billions of dollars’ worth of damage to into, the large-scale dynamics of the delta. Comprehensive data collection assets and livelihoods and wiped out achieved development gains. Managing and analysis in combination with state-of-the art numerical modeling (2D and these risks is one of the cornerstones of ADM. Investments made over the 3D) are performed with regards to aspects such as bank erosion, tidal river past few decades to reduce risk in the coastal zone have clearly paid off. For management, and long-term and large-scale morphodynamic behavior of the example, Chapter 4 shows that investments in EWS and disaster preparedness delta. All results feed into the future planning and design of the polder system. have drastically reduced loss of life from cyclones, and an economic analysis of past projects on strengthening polder systems repeatedly showed a positive Moreover, the program’s analytics have been designed to enrich the empirical benefit-cost ratio, confirming that these investments pay off in terms of risk evidence of multiple key coastal processes and issues. Notable among these are geomorphological attributes, the process of land subsidence, the impact reduction. This fact aligns with the global observation that investments in of tectonic effects, erosion rates, SLR, changes in tidal dynamics, river cross- climate-resilient infrastructure have a very solid economic justification (Box section changes, meander migration, shoreline changes, and the increase in 7.2). salinity and its impacts. Key outputs of the study include macro, micro, and mesoscale modeling of the long-term processes in the coastal zone, finalization Despite the achievements in risk reduction in Bangladesh, the risk profile of the of approaches for rehabilitation of the polders, including their phasing and coastal zone is still high and will further deteriorate under a no-action scenario. construction program, updated design parameters and specifications for The system-wide risk analysis of Chapter 3 shows that the current expected planning and design works, review of approaches for the management of annual damage from cyclone-induced storm surges is still very significant at polders, and an investment plan for the entire coastal zone. The initiative is about US$300 million. From climate change alone, this risk will increase by 90 also undertaking activities for the capacity building of relevant professionals in percent in the coming 50 years. Other coastal risks prevalent in the coastal zone the planning, design, and sustainable management of polders. are salinity intrusion, erosion, and waterlogging. The damage associated with these risks is more difficult to quantify since they are more slow-moving threats Source: CEIP-I project documents. to the coastal zone. Overall, evidence clearly highlights the magnitude of the Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 243 current risks and how these risks will continue to evolve in time and space as a risk management framework includes clear roles and responsibilities for a result of ongoing climate change trends and socioeconomic developments. the different components of the risk management framework and the time These insights are indispensable for the adaptation strategies of the Bangladesh dimensions of such a framework (such as for renewal of standards). coastal zone. Second, uniform tolerable risk guidelines for supporting climate change ADM is an “approach to deal with uncertainties in a transparent and sensible and disaster risk management decisions should be developed and applied way to support decision making with regard to water policy, planning and consistently across projects and industries. Tolerable risk levels are currently infrastructural investments. It links current decision making to future choices” established on a case-by-case or project-by-project basis. The same applies (Deltares 2014). It thus emphasizes a forward-looking approach of dealing to the choice of performance criteria for the design of climate change and with uncertainties in a flexible manner, with risk as the guiding principle. The disaster risk management solutions, such as the flood protection standards potential of using risk as a basis for ADM has been further evaluated in Chapter adopted for the design of coastal embankments. The inconsistent use of risk 5. Risk management approaches have proven highly successful in other thresholds and design standards result in the inefficient use of resources and countries and industries in controlling hazard, vulnerability, and exposure in make it harder to evaluate which areas need additional investments as a result an integrated and continuous manner. Three key issues were identified when of climate change. Using a uniform set of tolerable risk guidelines throughout comparing international best practices to current risk management practices in Bangladesh, which form the basis of the recommendations below. Box 7.2: The Economic Case for Investments in Climate-Resilient First, an integrated risk management framework should be developed for Infrastructure Bangladesh that would allow for continuously improving coastal resilience. Successful risk management is a cyclical process that involves strategic Multiple initiatives have demonstrated that investing in climate-resilient planning, design, and O&M. These activities are carried out by different entities. infrastructure will pay off. For instance, on the 2019 International Day for A risk management framework ties these activities together. The absence Disaster Risk Reduction (13 October 2019), UN Secretary António Guterres of an overarching scheme for directing and controlling organizations with mentioned that “for every dollar invested in climate-resilient infrastructure, respect to risk complicates the alignment of climate change and disaster risk six dollars are saved.” This statement is backed up by other recent reports management programs in Bangladesh and makes it more difficult to exploit stating similar numbers, such as the 2019 Global Commission on Adaptation’s synergies between multiple risk management projects (such as building disaster report Adapt Now claim that investment in resilient critical infrastructure shelters, restoring embankments, combating erosion). A fuller understanding has a benefit-cost ratio of 4:1 and can contribute to the Triple Dividend of of the potential synergies between programs may lead to the use of scarce Resilience (see Section 7.8 for further details) in action by avoiding losses resources in more cost-effective ways. For instance, investments in shelters, and stimulating economic development, and if implemented well, can have EWS, coastal embankments, and mangrove afforestation all impact the risk of social and environmental benefits (GCA 2019). Similarly, the 2019 Lifelines flooding in Bangladesh’s coastal zone, albeit in different ways. Also, it would report by the World Bank showed that the extra cost of building resilience into allow a more proactive approach to coastal resilience envisaged by the BDP infrastructure systems is about 3 percent of the overall investment needs and 2100 and the Second Perspective Plan of Bangladesh 2021-2041, in which could unlock approximately US$4.2 trillion in economic benefits in developing strategic investments are less post-disaster driven and more forward looking, countries over the lifetime of infrastructure investments (Hallegatte, Rentschler, making sure that development gains are not lost from inadequate O&M. Such and Rozenberg 2019). Bangladesh: 244 Enhancing Coastal Resilience in a Changing Climate the entire risk management process will ensure that the decisions and actions of management in Bangladesh. The BDP 2100 lists several general principles the organizations involved in the different parts of the risk management cycle that could be used as the starting point for this endeavor. remain closely aligned. Moreover, in numerous countries and sectors worldwide, risk has proven to be a useful tool for establishing and communicating the • Mainstream a risk-based approach in the entire planning process of coastal urgency of life safety interventions. Clear tolerable risk guidelines can facilitate interventions, taking present and future uncertainties into consideration. evaluations of investment opportunities and further improve the transparency This approach should apply state-of-the-art techniques to quantify risk, of investment decisions. including the use of robust decision-making tools and methods that account for present and future natural and socioeconomic uncertainties Third, improving and updating technical guidelines for the design of coastal to ensure that selected interventions are effective under a wide range of interventions is necessary in Bangladesh. For example, the current design scenarios. guidelines were introduced in the 1980s, with new knowledge and best practices developed in the meantime in Bangladesh and abroad, for example, • Update and refine technical guidelines for coastal interventions with state- the probabilistic design of flood defense systems. Improved design standards of-the-art techniques, including extending the guidelines to new types of should utilize the available morphological models and new data that is being interventions (such as nature-based, hybrid, and soft solutions). collected in order to support the technical guidance of structural designs given the local environmental conditions. Also, as the current technical guidelines mainly focus on hard structures, there is a potential to develop guidelines for the design of complementary soft and hybrid solutions for the coastal zone in Bangladesh (for example, a combination of mangroves, embankments, and nourishments as identified in Chapter 6). Knowledge sharing across countries is essential for this, as many countries intend to develop such guidelines in line with international calls to embed natural and hybrid solutions in design (see Recommendation 4). Given the potential benefits of implementing a risk management framework that is tailored to the challenges facing Bangladesh’s coastal zone, specific recommendations are to: • Develop a risk management framework for the coastal zone, including a clear set of roles, responsibilities, and time horizons per action. The framework should tie together planning, design, and O&M in a continuous and cyclical manner. Mahfuzul Hasan Bhuiyan • Develop a set of tolerable risk guidelines for supporting risk-informed decision-making by the different entities that are involved in coastal zone Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 245 7.4. Recommendation 4: Complement infrastructure There is vast potential to use nature-based solutions, specifically, combinations interventions with nature-based solutions to enhance resilience of nature-based and grey infrastructure solutions or hybrid solutions (see and effectiveness also Chapter 6) in the Bangladesh coastal zone. Given the high level of risk in Bangladesh, nature-based solutions can effectively complement existing or Key message: Acknowledging that the coast is highly dynamic but also very rich new structural interventions. Sand nourishments and mangrove forests have in terms of natural resources and assets is essential. The natural environment the potential to reduce the acting forces on the riverbanks, thereby reducing provides a great opportunity to reduce risk while providing additional services the length of bank protection works needed, while also reducing the required to society. Smart hybrid combinations of traditional infrastructure with nature- level of embankment crest height and design overtopping volume. In addition, based solutions like sediment solutions (such as nourishments) and mangrove there is substantial evidence that natural infrastructure and combinations of restoration for protection against cyclones and erosion should be pursued in natural and built infrastructure enhance coastal resilience by providing essential future programs. However, developing and monitoring pilot projects are key to services (such as flood protection), while also providing important co-benefits learning from best practices and establishing guidelines for the implementation (such as economic growth, fish habitat, carbon capture). Social forestry projects, of such solutions in different parts of the coastal zone. for instance, provide important revenue streams for those involved in planting and maintenance. Moreover, sand nourishments may provide opportunities for Bangladesh’s coastal zone has a dynamic and rich portfolio of natural economic growth via tourism, as nourishments provide space for allocating assets. Despite their dynamic nature, coastal ecosystems have the potential multiple functions along the coastline while sustaining the attractiveness to reduce risk to lives, livelihoods, and infrastructure. For instance, the tidal of the waterfront (de Schipper et al. 2021). Although several projects have sedimentary systems with mangroves scattered across the coast provide demonstrated the potential for incorporating nature-based solutions in design natural buffers against hazard impacts such as cyclones. Traditionally, a range (see Box 7.3), their implementation is still in its infancy, and several challenges of grey infrastructure has been implemented to combat flooding and erosion. remain. If designed well, these flood protection interventions with extensive bank and slope protections (such as revetments and breakwaters) perform well under extreme conditions, which for the highly vulnerable Bangladesh coastal First, the benefits and costs of nature-based solutions should be quantified zone is a necessity to protect lives and livelihoods, but these are often quite and the opportunities and barriers to scale up interventions identified and expensive. For example, 25 percent of the total budget of the recent CEIP-I documented. As mentioned, complementary nature-based solutions can lower of US$400 million is being spent on bank and slope protections alone. High the investment needs of structural solutions. For instance, sand nourishments costs are the result of, among others, the necessity to produce, transport, and can often be constructed with locally available materials, as was shown in the place a large number of concrete blocks for these types of protection works. case study of the Bogi area in Polder 35/1. As such, the necessary maintenance Grey infrastructure solutions are not always flexible or adaptable to changing costs associated with the proposed solutions can also be reduced. However, boundary conditions (which hinder Recommendation 3 on ADM). For example, before nature-based solutions can be widely adopted, the costs and benefits bank and slope protections are usually designed for a specific design wave should be quantified, which are often more uncertain than conventional hard load. If these loads increase, larger blocks will be necessary, with substantial infrastructure solutions. Studies have shown that planting mangrove forests associated costs. In at-risk settings, such as Bangladesh and other highly can have larger benefit-cost ratios than conventual infrastructure systems vulnerable coastal regions, grey infrastructure is essential, although there are when it comes to risk reduction (Narayan et al. 2016). However, it is hard to opportunities to strengthen resilience by supplementing this infrastructure with softer approaches. say how universal this is and what the reliability of such interventions is under different extreme loads. For instance, it is unclear how well a mangrove forest Bangladesh: 246 Enhancing Coastal Resilience in a Changing Climate could reduce wave heights during a cyclone if extreme winds wash away part Box 7.3: Putting Nature-Based Solutions into Practice as Part of the of the mangrove forest. Detailed project evaluations to understand what works, CEIP-I and under which conditions, are needed to move to a widespread adoption of using nature in design. These best practices should also be incorporated into The CEIP-I incorporates a nature-based solution initiative through the design guidelines (for example, the type of mangrove given local conditions, afforestation component, embedding social forestry as part of an overall sediment composition for nourishments, and dredging strategy). The same integrated protection program. In the CEIP-I, afforestation provides an additional holds true for the various co-benefits of hybrid solutions, although these are layer of protection to embankments and the livelihoods of communities, as often more difficult to quantify. it potentially reduces the impact of waves, tidal flooding, and storm surges, and creates income-generating opportunities. Plantations of selected species, including mangrove and other saline tolerant species, are being undertaken Second, establishing monitoring systems to evaluate the performance of nature- to play the important role of a protective belt at the tidal inundation zone based designs is imperative. A significant additional benefit of nature-based or on the river side of the embankment. The species are carefully selected hybrid solutions is their flexibility and/or adaptability to changing conditions considering the location, the level of protection provided, and co-benefits to along the coast. Nature-based solutions are less intrusive and can be adapted to the local population, including a range of commercial wood, fruit, and other changes caused by morphological behavior and/or climate change. However, to shallow rooting tree species. The afforestation component is embedded within do this, regular monitoring is needed. For example, at Himchori beach (Chapter a social forestry approach by engaging local communities to ensure benefit 6), large sand nourishments are proposed to counteract coastal erosion. For sharing and achieve social, environmental, and economic sustainability. The this case study, it is not entirely clear how the nourishments will develop in component includes efforts to increase community awareness of the protective time as a result of continued coastal transport that may block the opening and productive functions of trees and build the capacity of local institutions of streams beside the beach. If needed, additional dredging or nourishments and communities in secondary maintenance schemes of the foreshore and can be performed to account for changes in the predicted behavior of the embankment afforestation, and protection of the embankment against toe solution and prevent the river mouths from closing. Moreover, the potential for erosion. Key lessons from past embankment afforestation projects have been taken into account in the implementation of this component. This includes mangrove reforestation along the coastline (Chapter 6) is critically dependent lessons in participatory planning, selection of forest types and species, selection on the erosion rates, SLR, and salinity levels, which are all uncertain. Hence, the of beneficiaries, post-planting O&M, plantation protection, harvesting of wood implementation of nature-based and hybrid solutions should go hand in hand and non-wood forest products, and benefit sharing. with the establishment of monitoring systems to evaluate the performance of the interventions over the project lifetime. Source: CEIP-I project documents. Third, suitability maps should be developed that identify the potential for incorporating nature-based solutions into the design. To understand the scale efficiently such that ecosystems could be restored. Such suitability criteria can and potential for nature-based solutions, and identify places with the largest be combined with other indicators, such as, among others, the potential for benefits, mapping exercises with suitability indicators should be established. risk reduction, proximity to settlements, proximity to coastal embankments, For instance, in Chapter 6, the suitability of mangrove reforestation was biodiversity indices, and salinity levels. Similarly, such suitability proxies can be identified based on the rates of erosion, the expected SLR, and the existence developed for other hybrid solutions, such as beach restoration. In this way, the of natural mangrove forests for natural colonization. Thus, places where the areas with the highest potential can be prioritized, and co-benefits maximized. mangrove forest has been degraded over the years could be reforested more Large-scale feasibility maps also help in deriving a long-term strategy for the Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 247 scaling up of nature-based solutions, as they prevent initiatives happening in 7.5. Recommendation 5: Incorporate risk-sensitive land-use isolation, and help to set suitable targets for widespread adoption of nature- planning to guide appropriate activities based on integrated coastal based solutions. zone management practices Embracing nature-based solutions in the design of new interventions along the Key message: Changes in land use and socioeconomic characteristics will coastal zone is therefore recommended to further increase coastal resilience shape the inherent composition of the coastal zone in terms of what is at risk, while also providing opportunities for economic growth and other social where, and how. Given the longevity of investment horizons, and the often and environmental benefits. Specific recommendations about nature-based complex interactions between society and the natural and human-made solutions are to: assets, risk-sensitive land-use planning should be at the core of coastal zoning policies. Risk-sensitive land-use planning can take place on different scales and • Set up and implement pilot projects with nature-based and hybrid solutions. should be based on various plausible land-use and socioeconomic scenarios, Pilots will support knowledge development and help to mainstream these contingent on the changing environmental conditions. Such scenarios not only solutions. Chapter 6 provides several conceptual solutions which could be help in testing the robustness of interventions but can also inform expected an excellent starting point for potential pilots (Cox’s Bazar and Kuakata Sea migration patterns and policies to cope with this, as well as zoning policies for Beach). the spatial allocation of present and future economic activity. • Develop knowledge, tools, and guidelines through these pilot projects Changes in the social and economic demographics of the coastal zone will about the implementation of nature-based and hybrid solutions in determine what is at risk, and where and who is impacted, which is often Bangladesh based on national and international experiences. This will aid in a larger uncertainty than uncertainties around changes in hazards as a understanding where these solutions have been successfully implemented result of climate change. Over the last couple of decades, major land-use and identifying factors that determined their effectiveness, which can help transformations have taken place, such as the expansion of shrimp farming, the in setting guidelines for design. ongoing degradation of natural ecosystems, and the growth of urban areas and infrastructure. Moreover, socioeconomic changes have transpired, such as the • Establish a monitoring framework to track the performance and evolution decline in poverty, increasing employment in the manufacturing and service of hybrid solutions over space and time. This not only allows for ongoing sectors, changing migration patterns, more varied housing types, and more knowledge improvement on the functioning of hybrid solutions, but it also options in access to finance. All these developments shape the spatial location provides flexibility to adapt the interventions over time if required. of economic activities, the interaction of society with natural and human-made assets, and the risk profile of those inhabiting the coastal zone. • Create coastal-zone-wide suitability maps for various nature-based solutions based on a number of proxy indicators. Such suitability maps can Since most investments have long-term horizons, it cannot be assumed that the then be used for the prioritization of initiatives and to help in creating a current occupation and household characteristics will stay constant over that shared vision and suitable targets for the implementation of nature-based time frame, especially in rapidly developing areas such as coastal Bangladesh. solutions over time. Far too often, changes in the vulnerability and exposure of people and assets are not fully explored, and the associated effectiveness of interventions might be over or underestimated. In the BDP 2100, the emphasis is on an integrated Bangladesh: 248 Enhancing Coastal Resilience in a Changing Climate Ismail Ferdous Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 249 and multisectoral approach to natural resource management. Through four First, scenarios of future socioeconomic development should be considered plausible scenarios, investment strategies can be evaluated in terms of their more explicitly in design. Many complex feedback and interactions exist performance and suitability. Although these scenarios are a step in the right between adaptation interventions and socioeconomic development. In fact, direction when it comes to the exploration of future scenarios and the ability many adaptation interventions, such as rural accessibility or financial inclusion, to evaluate the robustness of interventions, they are only indicative and have implications for development, whether or not the climate-related risk considered the “end points” of the many plausible futures. Moreover, although will change, and are heavily influenced by the development pathway and the BDP 2100 envisions an integrated coastal zone planning framework, which transition of local communities (Jafino, Hallegatte, and Rozenberg 2021). The refines the rather land-centric view of the 2005 CZP, institutional limitations transformation of local economies, for instance, depends on how they benefit in coastal planning should be addressed first before such realizations can be from local infrastructure (such as drainage systems) and natural resources made in practice. In particular, a clear land-use planning policy is needed, (such as fisheries) and hence, the interventions that improve them. Moreover, which addresses questions like: (1) Who lives where given the expected change interventions in themselves can lock in a certain development pattern. For in local environmental conditions? (2) Where will economic activity take place? instance, the hybrid coastal protection schemes (for Kuakata Sea Beach and and (3) What do different futures mean for migration patterns in the coastal Kolatoli Beach, see Chapter 6) could promote tourism and accelerate the zone? To accommodate this, there are three areas to take into consideration. movement of people from traditional employment into the service sector. To fully capture these uncertainties, plausible scenarios of land-use change (for S M Mehedi Hasan Bangladesh: 250 Enhancing Coastal Resilience in a Changing Climate example, transition out of agriculture, rural-urban migration) and socioeconomic Second, although migration is often seen as a negative outcome, zero characteristics (such as housing types, financial access) should be developed. migration should not be seen as a desirable policy objective. When people These scenarios can then be used to compare alternative designs in terms of are unable to cope or adapt, migration (either temporal or permanent) is a their feasibility and effectiveness, and better assess how portfolios of hard suitable adaptive strategy (Ayeb-Karlsson et al. 2016). In the rural areas of and soft interventions should be balanced. In the end, interventions should be coastal Bangladesh, 30 percent of households already have migrant members, robust under a large variety of scenarios in order to perform well, especially if of which half of them have left the coastal zone (Lázár et al. 2020). Hence, planning horizons are long. There are many tools available today to perform migration is prevalent and arises from the interaction of social, economic, and such a robustness analysis that have clearly demonstrated the added value of environmental push and pull factors. Climate change may cause some areas to performing such analysis for large investment decisions with long time spans become uninhabitable, making adapting livelihoods in such areas undesirable, (Marchau et al 2019). The four development scenarios in the BDP 2100 are as it may prevent some workers from finding more secure and higher-wage a good starting point for this but should be tailored to the local scale and jobs elsewhere. Therefore, depending on the local context and the expected combined with narratives of how households will further develop as a result of changes in the local environmental setting, a decision should be made whether changes in the economy and the natural environment, as done in other projects to support migration or promote livelihood transformation. For instance, for in Bangladesh (Lázár et al. 2020). poor households near to the Sundarbans, it was found that improving rural accessibility to local markets (as some isolated communities travel 14 hours S M Mehedi Hasan Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 251 to reach market centers) combined with microfinance could help enhance Third, land-use zoning policies should be developed that are coherent with the resilience, as it would allow them to sell their products at markets or pursue aforementioned socioeconomic scenarios and integrated into the proposed eco-friendly livelihoods (Dasgupta et al. 2021). Moreover, as the spatial location risk management framework. Land-use planning helps with the allocation of economic activity is expected to change, for instance, the partial transition of economic activities and can guide the spatial direction of development. out of agriculture into the service sector and manufacturing and the expected If combined with an integrated risk management framework, considerable growth of tourism, migration is inevitable. Some studies predict a net in- cost savings could be achieved, as different activities need different types migration of the coastal zone, even under scenarios of SLR-induced flooding of interventions for adaptation and different levels of optimum protection (Bell et al. 2021), emphasizing that coastal cities need to prepare for a potential standards. For example, the four polder configurations highlighted in Chapter influx of migrant workers as economic amenities improve. Hence, both sending 5 underline that effective land-use planning in polder areas can effectively save and receiving areas can help influence migration by protecting coastlines, but costs, as locations with higher economic value will require higher protection also by providing income credits and housing subsidies for inevitable migration. standards, whereas areas with lower values of economic activity require lower Migrant-friendly cities (some of which are in the coastal zone) could potentially protection standards. For instance, areas that will continue to experience an be established through the development of smaller peripheral towns into expansion of shrimp farming will need alternative adaptation options compared migrant-friendly and climate-resilient cities (Khan et al. 2021). These envisioned to regions with a continuous expansion of agricultural production. Further, migrant-friendly cities could have potential to absorb some of the climate land-use planning can help to avoid conflict and tensions between households migration but would require supportive mechanisms to provide livelihoods and engaged in different land-use practices, as is prevalent in some polder systems. skills development opportunities, low-cost housing, and resilient infrastructure Similarly, zoning policies should be established that cover larger-scale land- services to new settlers, as well as the legal, policy, and institutional capacities use allocation, which can help allocate resources when decisions have to be to promote internal migration (Khan et al. 2021). made about which areas to protect and which areas to retreat from if climate Ismail Ferdous Bangladesh: 252 Enhancing Coastal Resilience in a Changing Climate change makes it too costly to protect the entire populated zone. Enforcement needs if aligned with the development of an integrated risk management of such zoning policies would also be required and would need to be backed framework that establishes optimum protection levels for different areas by the right institutions. Moreover, land-use zoning policies can help guide within a polder. the spatial development of economic activities and urban development. The GoB has outlined plans to invest in several SEZs in the coastal zone. These SEZs Box 7.4: Special Economic Zones and Improved Logistics Services are major drivers of employment and local economic growth, as they often go hand in hand with infrastructure development, the growth of settlements, and SEZs and export processing zones have been proposed as a viable solution indirect employment opportunities (Box 7.4). Making sure these developments to promote economic growth, create jobs, and support the industrial take place within a coherent coastal zoning framework, instead of happening transformation of the country given the increase in agricultural productivity. in silos, is important to understanding how such developments need to be After the Bangladesh Economic Zones Act was passed in 2010, the Bangladesh accounted for in large-scale investment decisions, and to understanding the Economic Zones Authority was established to oversee the establishment of spatial drivers of economic change. economic zones in the country. With support from the World Bank, through the Private Sector Development Support Project, US$3.9 billion in direct private To facilitate better land-use planning, specific recommendations are to: investment has been generated in the economic zones across 1,500 acres of land, which helped create jobs for 41,000 people and 21,000 trainees (World • Include socioeconomic development pathways more explicitly in the Bank 2021). However, SEZs rely on resilient infrastructure as an enabling factor design process of coastal resilience interventions to identify complex for growth. Hence, alongside the creation of land, the project created roads, feedback between development and the effectiveness of interventions. In embankments, bridges, electricity substations, and water reservoirs to support the end, designs should be robust against uncertainties associated with industrial activity. The current and proposed SEZ zones are strategic assets for both climate change (such as the amount of SLR) and socioeconomic the future economic development of the coastal zone. The SEZs, near economic development (such as access to finance, improved housing types), with the hubs close to rivers and seaports, can employ millions of workers, including latter often having larger inherent uncertainties. those that have to migrate away from at-risk coastal areas (Khan et al. 2021). Apart from the SEZs, improved transport connectivity and logistics services • Accommodate internal migration by the development of policies and are key to unlocking the economic growth potential of the coastal zone. At mechanisms that remove the barriers of out-migration from high-risk areas. the moment, both the logistics performance within the country and between The envisioned migrant-friendly cities in the coastal zone, which could Bangladesh and neighboring countries is low. Congestion on roads and potentially absorb half a million migrants each, need to be integrated into highways, and the inadequate capacity of the main economic transport corridor the wider land-use planning of the coastal zone so as not to counteract between Dhaka and Chattogram has led to poor reliability of services, resulting existing development plans, and hence, be able to prioritize and allocate in high transport costs and the need for inventories. Analysis by the World Bank resilience investments accordingly. showed that improving logistics services could increase exports by 19 percent and generate employment opportunities across the country (Herrera Dappe et • Establish coastal-wide zoning policies on different spatial scales. Large- al. 2019). On top of that, another study showed that removing existing trade scale zoning policies can help identify areas that are potentially becoming barriers between India and Bangladesh could increase income in Bangladesh uninhabitable and areas that are suitable for promoting economic by 16.6 percent, with higher overall benefits in the logistic hubs of Chattogram growth. On a polder level, land-use planning can help guide investment (Herrera Dappe and Kunaka 2021) 7.6. Recommendation 6: Support inclusive community participation, to increase their resilience and reduce their vulnerability to multiple coastal local institutions, and livelihoods adaptation for sustainable and climate risks (Forsyth 2013). Moreover, local involvement in the design, resilience implementation, and O&M of large-scale interventions have the potential to make such interventions more sustainable and in line with local needs. Key message: Natural hazards and climate change impacts can directly alter the habitability and productivity of coastal areas. Strengthening the adaptive Bangladesh is an initiator globally with respect to bottom-up adaptation capacity of coastal livelihoods ensures that coastal inhabitants have the ability planning taking place through locally-led coordination, mobilization, and and means to make a living under the various shocks and stressors they face. learning (Mfitumukiza et al. 2020). Key to the success of adaptation efforts However, before such efforts can be scaled up and mainstreamed into national is the involvement of local communities in the planning, implementation, adaptation plans, a systematic framework should be developed that can track and monitoring process (see Box 7.5). In particular, engagement with poorer the development of adaptation efforts in communities and investigate drivers and more vulnerable people in the community is essential to identifying the of and barriers to success. On top of that, local institutions with a diverse challenges posed by climate-related risks and suitable responses (Forsyth representation of social groups, upgraded capacity, sufficient resources, and 2013). Such participatory approaches also help in understanding the needs clear roles and responsibilities should be established or strengthened to make and aspirations of these groups. Bangladesh is actively trying to scale up its sure scaling efforts are sustainable. best practices and lessons learned from local adaptation plans into its NAPAs and national long-term sustainable development plans (such as the Draft Communities in the coastal zone of Bangladesh are at the forefront of coastal Mujib Climate Prosperity Plan). For instance, within the Draft Mujib Climate hazard and climate-related impacts, particularly the low-income groups Prosperity Plan, the GoB has outlined its ambition to mainstream locally-led within these communities. The impact of natural hazards can influence human adaptation plans into national adaptation planning by establishing “Locally- development by destabilizing the livelihoods of coastal communities, in particular Led Adaptation Hubs” throughout the coastal zone (by 2030 all vulnerable for those livelihoods that are critically dependent on the natural environment areas will be covered) that will act as the focal points for projects and serve as (such as farming, fisheries, forestry). Strengthening the adaptive capacity of the venue for discussions and consultations. Despite the successful initiatives, coastal livelihoods ensures that coastal inhabitants have the capabilities and a number of challenges have been identified that have to be overcome to help assets (physical assets, rights) to make a living under the various shocks and scale up and accelerate community livelihoods adaptation. stressors they face. Community livelihoods adaptation is at the heart of this, which is defined as the adjustment of livelihoods activities to mitigate harm First, community involvement in design and implementation should be or exploit benefits from changing conditions (Kulsum et al. 2021). Livelihoods mandated in projects. The foundation of community livelihoods adaptation can be improved on an individual level (diversification of income sources), the efforts is the utilization of local knowledge and aligning the project design with community level (basic infrastructure, utilities, healthcare, digital solutions), the aspirations of social groups within the community. There are a variety of and the regional level (improved market access, polder construction). In order factors that can prevent the most marginalized from successfully adapting, such to design sustainable solutions, no matter the scale, interventions should be as unequal power structures, unjust market incentives, top-down planning that aligned with the needs and aspirations of local communities, and communities clashes with local realities, insecure land tenure, or the incorrect interpretation should be actively involved throughout the design process (Mfitumukiza et of local norms and values (Mfitumukiza et al. 2020). Hence, identifying and al. 2020). It has been recognized that local communities have the skills, local considering these varied factors can help improve the inclusivity, uptake, and knowledge, experience, and networks to self-organize and undertake actions sustainability of these solutions, while also creating a sense of ownership by Bangladesh: 254 Enhancing Coastal Resilience in a Changing Climate Box 7.5: Examples of Successful Community-Led Bottom-Up Adaptation Projects Two examples of successful community-led bottom-up adaptation projects are the Community Climate Change Project and the Char Development and Resettlement Project (CDSP). The Community Climate Change Project, a project initiated by the GoB and supported by the World Bank and the Bangladesh Climate Change Resilience Fund, a multi-donor trust fund, aimed to enhance the capacity of selected communities to increase their resilience to the impacts of climate change, including implementing community-driven climate change adaptation projects in the saline-prone areas of the coastal zone. For instance, in highly saline zones, where conventional crops could not be grown successfully, mud crab farming was introduced, which is tolerant of high salinity levels and for which there is growing demand on international markets. In addition, rainwater harvesting, and small-scale desalination plants were constructed to provide reliable water sources to the local communities. Capacity building was performed throughout to raise the awareness of local communities about the climate risks that they face and ways to better manage adaptation activities. CDSP is a multiagency project led by the BWDB and has the Ministry of Land, the LGED, the Department of Agricultural Extension, the Forest Department, and the Department of Public Health Engineering as implementing partners, The grant support from the Government of the Netherlands and the contribution from the GoB financed the first three phases of the CDSP. In the fourth phase, the United Nations International Fund for Agriculture Development also provided credit support to the GoB (see CDSP, n. d. for an overview of the different phases). Starting from 1994, the CDSP strived to improve the economic situation for people living on newly accreted chars in coastal Bangladesh, which are often vulnerable and exposed to flooding and other coastal hazards. Participation of local communities and a bottom-up approach was a core element of the CDSP’s design. The CDSP effectively managed water resources to protect the land from tidal and storm surges, improved drainage, and enhanced accretion. These reduced crop damage and improved farming practices, which led to enriched cropping density. Upgraded road communication reduced the cost of transporting agricultural products. Tubewell water and hygienic latrines are now easily accessible to the community. Key to the project’s design is that it established multiple gender- balanced Field Level Institutions (FLIs) to ensure community engagement and adaptation in all stages of the project cycle. These are locally-led community- based organizations consisting of representatives of the settlers in the chars. The FLIs make it possible for community members to participate in the planning, implementation, monitoring, evaluation, and sustainability of the project activities through O&M. The FLIs ensure that they address the local needs and interests in planning, execution, and maintenance, which stimulates a sense of ownership of the project. the community. Within the CDSP, gender equality in public participation was stakeholder consultations helped identify the needs and aspirations of polder emphasized. Most of the FLIs consist exclusively or predominantly of women to inhabitants. For instance, in many polders, communities expressed that the make sure solutions are acceptable to the wider community and tackle multiple coastal embankments brought a sense of permanence to the community, with gender barriers. For instance, care was taken that women-headed households, a recognition that the embankments are their lifeline with the development which often have insecure land rights, get possession of land and the associated perspective of the communities centered around them (Rahman et al. 2021). ownership rights. Within the CEIP-I, extensive community involvement through The same holds for the road construction on top of the embankments that are Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 255 perceived as the precondition to development, as they facilitate connectivity teaching other farmers, and of the local WMO to take on the role of managing with cities (Rahman et al. 2021). These two examples illustrate that public conflict and the construction of small-scale infrastructure. This ensured that the participation and the involvement of various social groups early on in, and adaptation initiative was fully operational without continuous involvement of throughout, the process is essential to empowering local communities and the organization that provided the initial intervention (referred to as “hands-off ensuring gender equality. Such mandates for community involvement and scaling”). Hence, strengthening local institutions by building capacity, providing incorporation of gender requirements, although through various degrees resources and skills, and specifying the roles and responsibilities for scaling up of intensity, can help stimulate community-led development and promote the initiative is essential. To make the envisioned Locally-Led Adaptation Hubs inclusive practices. work, it is imperative that the right type of mechanisms are put in place to facilitate this transition and to make sure that continuous learning is embedded Second, communities should be involved in the O&M of livelihoods adaptation within the planning and implementation process (Reid and Huq 2014). solutions to enable the sustainability of project outcomes. Past projects have demonstrated that the sustainability of interventions over time is determined Third, tracking the success of livelihood adaptation efforts by evaluating the by the transfer of roles and responsibilities for O&M from the NGO or other reduction of vulnerability over time is key to learning from best practices and development agency to the local community. For instance, under the Blue Gold channeling funds to those areas that are lagging behind in their vulnerability Program (see Chapter 4), the community-led agricultural WMOs were scaled reduction. In most NGO-funded adaptation projects, there are project-specific up from a pilot study to a total of 71 schemes. Key to this scaling up was the outcomes and evaluation criteria, which makes it hard to compare outcomes willingness of local communities to co-finance the initiative, of local farmers to across projects and generate generalized insights given the large variation in take on the responsibility of improving agricultural production management and community characteristics. For instance, a study that compared community- level resilience indicators across communities in nine countries (including Bangladesh) found that communities could be clustered according to some guiding socioeconomic characteristics that predict their level of community resilience (Laurien et al. 2020). Establishing such an indicator framework using mixed-method solutions (such as surveys, discussion groups, secondary data) that can be regularly updated could create a typology of coastal resilience, which could help target suitable community-level adaptation options. This not only allows tracking of the progress of adaptation over time, but also helps with exploring the enabling factors for successful adaptation. A coordinated effort is required among NGOs, development agencies, and local and national governments to ensure consistency of implementation. Bangladesh has been successful in designing and implementing locally-led adaptation interventions and has the ambition to mainstream this into national Ahmadul Haque @CPP policies. However, before such ambitions can be achieved, a number of necessary steps need to be taken to reach its full potential. Specific recommendations are to: Cyclone Preparedness Program (CPP) volunteers Bangladesh: 256 Enhancing Coastal Resilience in a Changing Climate • Establish mechanisms through which various social groups are included in 7.7. Recommendation 7: Establish an integrated framework the design, implementation, monitoring, and maintenance of interventions of performance criteria of interventions that goes beyond risk to create acceptable, inclusive, gender-just, and equitable interventions, reduction and includes growth, wellbeing, and sustainable and ensure that the development aspirations of all members of the development at its core community are achieved. Past projects have illustrated that emphasis on such wider participation results in more sustainable solutions. Key message: Coastal resilience efforts take place in and around coastal communities and are often aligned with ongoing development efforts. • Build a knowledge base of good practices for scaling community-based Therefore, it is important to ensure that development objectives are well adaptation measures, resulting in hands-off scaling that relies on the integrated into these efforts to reap the large gains that can be made to self-organization of communities. Experience has shown that setting up adapt to a changing climate while achieving sustainable development goals. local institutions with sufficient capacity, resources, and clear roles and Alternative policy evaluation frameworks should be developed that explicitly responsibilities is necessary to achieve this. Community participation take development objectives into consideration alongside wider planning throughout the process is key to enabling this. efforts to align different program objectives across sectors in order to benefit from positive cross-sectoral spillovers. • Set up a monitoring framework that allows the tracking of adaptation over time and the allocation of funds to those communities that are Development and DRR are intrinsically linked to one another in the coastal outperforming or those that need additional support. Suitable indicators zone. The natural and engineered assets in the coastal region are enablers of to track progress, which can be generalized across areas and are easy to economic growth, as most households derive income from the services that measure, should be identified. These indicators can be aligned with other these assets deliver (such as agriculture, fisheries, aquaculture, tourism). On the initiatives, such as the SDG indicators, and should be complemented with one hand, the interdependency of assets and development means that risk from data on the communities’ social, economic, and ecological characteristics natural hazards can directly impede development efforts. For instance, Cyclone to investigate the barriers and enabling factors for successful adaptation. Aila (2009) increased unemployment from 11 percent to 60 percent in surveyed coastal communities in the southwest (Akter and Mallick 2013). Moreover, faced with chronic risk, households may save or invest less, preventing them from accumulating wealth, or they may make the decision to migrate away from risk-prone areas. On the other hand, development influences DRR, as the accumulation of assets, transition of livelihoods, and land-use changes all affect the risk profile of households. Traditional tools to evaluate the costs and benefits of risk reduction measures are not always capable of capturing the development gains and the wider wellbeing implications of those households that benefit from interventions. Ignoring the wider wellbeing impacts of interventions might mean that the prioritization of investments is not targeted to those that need it or are misaligned with other development objectives (such as poverty reduction). Moreover, as mentioned Chapter 7: Habibul Haque A Way Forward: Seven Recommendations for a More Resilient Coast 257 Mahfuzul Hasan Bhuiyan Mahfuzul Hasan Bhuiyan Mahfuzul Hasan Bhuiyan Mahfuzul Hasan Bhuiyan Bangladesh: 258 Enhancing Coastal Resilience in a Changing Climate Mahfuzul Hasan Bhuiyan Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 259 before, DRR efforts, and nature-based and hybrid interventions (for example, reduce the transportation costs to sell products at local markets. Although mangrove restoration) have wider co-benefits for local communities and other evidence exists that past interventions have significantly boosted agricultural sectors (as discussed in Chapter 6). These co-benefits need to be identified production and income, and roads have increased accessibility to markets, early in the design process to maximize their potential and build capacity and such wider economic benefits are often not included in cost-benefit analyses. complementary interventions to fully utilize them (for example, designing in To explore who might benefit from interventions and to target specific community involvement in mangrove restoration and conservation). Three socioeconomic groups, detailed information on the location and characteristics areas have been identified that serve as focal points for the prioritization and of households is needed, which is often not available or if available, is not design of future interventions. regularly updated. Innovations such as remote sensing to map settlements and downscaling of aggregated household survey data are a good starting First, the prioritization of interventions, such as the new embankment upgrades point for identifying potential beneficiaries of interventions. Moreover, it under a next generation of coastal resilience investments should include a allows for the evaluation of whether and how past interventions have had a wider set of evaluation criteria compared to the narrow framing of benefits positive effect on targeted communities. Building up the knowledge base on in terms of risk reduction only. A growing body of work has indeed shown what works, and under which conditions, is essential to avoiding maladaptation that the traditional evaluation criteria, which express risk reduction in terms of (that is, the potential for adaptation measures to cause further inequalities) and the prevented damage to physical assets, are inherently biased towards richer identifying complementary measures for success (see Box 7.6). This will help households as they own by definition more assets (Hallegatte, Bangalore, and unlock the potential for the Triple Dividend of Resilience (see Section 7.8 for Vogt-schilb 2016; Markhvida et al. 2020; Verschuur et al. 2020). On the contrary, further details). low-income households often have limited capacity to cope with the adverse effects of shocks, and hence take longer to recover. For instance, multiple Third, a framework to evaluate co-benefits and trade-offs between different studies in Bangladesh have illustrated that the poor are relatively more exposed development objectives should be established in order to identify the most to natural hazards and lose a larger percentage of their income or assets as a suitable interventions and to optimize budget allocation. Bangladesh is result of hazard impacts (Hallegatte et al. 2020). Therefore, bringing granularity considered a frontrunner in achieving the SDGs. Despite this, the impacts into the risk management framework, which allows for the estimation of of climate change have the potential to slow down progress. Recent work risk for different socioeconomic groups (by for example, income types), and has illustrated that climate change adaptation can benefit multiple SDGs developing alterative risk metrics that better capture welfare impacts can help simultaneously if such co-benefits are identified in the early stages of design identify where investments can have the highest development gain. (Fuldauer et al. 2021). However, planning for the SDGs often happens in silos, making for misaligned planning and ineffective budget spending. Given the Second, the widening of the evaluation framework should be supported by major tasks at hand in adapting coastal Bangladesh to climate change and empirical evidence on who is benefiting from such interventions, through achieving the sustainable development agenda, any targeted action to align which mechanisms, and whether complementary interventions are needed. For adaptation spending with the SDGs will pay off. Doing this should start by instance, increasing the elevation of the embankments, thereby reducing the identifying how different adaptation measures are contributing to the various frequency of flood impacts, can help farmers to start investing in productive SDGs, and whether such interventions can partly substitute for investment assets (such as fertilizer, improved seeds) in order to boost agricultural made in the interrelated sectors. For instance, mangrove restoration can income. Complementary measures, such as improving accessibility through reduce wave impact and coastal erosion, but also promote the diversification improvements to the road network on top of the embankments can further of income streams (by providing habitat for flora and fauna and providing non- Bangladesh: 260 Enhancing Coastal Resilience in a Changing Climate Box 7.6: Example of Complementary Measures to Make an Intervention Work A good example of the use of complementary measures is the recent upgrades of the multipurpose disaster shelters that have added complementary inclusive features to their design, such as a place for livestock, separates spaces for women and nursing mothers, sanitary facilities, provision of rainwater harvesting, solar panels, and improved accessibility, such as the provision of ramps, to try to avoid the possibility that those already more vulnerable to disaster impact will decide not to evacuate. Moreover, the construction and renovation of cyclone shelters is combined with the construction of rural access and evacuation roads to reduce the travel time to reach a shelter. These cyclone shelters are also a good example of positive cross-sectoral spillovers because of their multipurpose uses. Most of the shelters are used as schools and community centers throughout the year, thereby contributing positively to the development of local communities timber forest products) and the capture of carbon, which can reduce additional • Advance the knowledge base and approach to identifying beneficiaries investments needed in other sectors. Such a universal cross-sectoral framework of adaptation interventions and their socioeconomic characteristics. thus helps to allocate budgets across sectors in order to maximize the overall Innovative data solutions, such as high-resolution population mapping, gain. can support this development by providing quantitative proxies for how various socioeconomic groups can benefit from interventions. Bangladesh has made significant steps in achieving coastal resilience and promoting sustainable development. Given the interdependency between • Better align coastal resilience efforts with cross-sectoral planning to achieve coastal resilience and development, and the fact that climate change has the the SDGs. Given the large interdependencies between the two and, hence, potential to slow down progress, development objectives should be more the cross-sectoral gains that can be made from improved resilience, the tightly coupled to coastal resilience efforts. Specific recommendations are to: potential for positive spillovers should be identified early on in the design and planning process to align objectives of various stakeholders, optimize • Develop a wider evaluation framework that can capture not only the budget allocation, and discuss trade-offs. To do this, a framework should effectiveness of interventions in terms of risk reduction but also the broader be developed that first maps all the interactions between the different wellbeing implications of coastal hazard impacts and climate change. In SDGs, which can be combined with the current and future plans of different this way, the prioritization of interventions is targeted to those that really sectors (such as water, energy, forestry). need it. Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 261 Tapash Paul Tapash Paul Tapash Paul Tapash Paul Bangladesh: 262 Enhancing Coastal Resilience in a Changing Climate 7.8. Coastal Resilience will Support Delta Prosperity the most obvious of the benefits from coastal resilience investments, it is not easy to measure given the unpredictability of the dynamics of any disaster The evidence presented in this report makes it clear that Bangladesh is at a event and other factors that influence both its impact and successful recovery. crossroads. The do-nothing scenario results in increasing risks to coastal communities that exceed the coping capacity of those exposed. However, with The second dividend is the unlocking of the short- and long-term economic concerted action, many opportunities lie ahead; the review and corresponding potential of disaster-prone regions by providing a higher sense of safety recommendations clearly indicate that investing in coastal resilience will bring and security. There is strong evidence that the mere possibility of a future multiple benefits in terms of avoided losses, wider economic benefits, and disaster has a real impact on present-day decisions and economic growth. social and environmental benefits, that is, a triple dividend. The risk of extreme weather events and disasters looms as an ever-present background risk. As a consequence, risk-averse households and private The way forward for Bangladesh is to encompass the fundamentals of the Triple firms avoid long-term investments in productive assets, entrepreneurship is Dividend of Resilience concept (Tanner et al. 2015) in its development plans restricted, and planning horizons are shortened, leading to lost development and policies, which will enable a proactive and informed approach to maximize opportunities. Coastal resilience measures that reduce this background risk the co-benefits of the coastal resilience process (Figure 7.1). The first dividend can have immediate and significant economic benefits to households, the is the basic rationale and common motivation for DRR investments—to save private sector and more broadly, at the macroeconomic level. For instance, lives, reduce losses, and promote effective recovery from disasters. While it is there is evidence that reduced background risk and effective risk management allow poor households to build up savings, invest in productive assets, and Figure 7.1: The Triple Dividend of Resilience improve their livelihoods. More generally, increased resilience enables forward- looking planning, long-term capital investments, and entrepreneurship—even if disasters do not occur for a long time. The third dividend is the generation of significant development co-benefits by pursuing the path of coastal resilience. Most investments in coastal resilience serve multiple purposes and are not solely designed to mitigate disaster impacts. Strengthened embankments can act as walkways, leisure areas, or roads; strengthened disaster EWS often also strengthen weather forecasting capacity, which can be used by farmers to know when to plant and harvest; and multipurpose cyclone shelters can be used as schools or community spaces when not being used as a shelter. Improved communications systems not only ensure better outreach in the event of a disaster but also support the commercial activities of local households and businesses. Integrating multipurpose designs into coastal resilience investments can save money and spur economic activities. These multiple uses of coastal resilience infrastructure, as well as the associated cost savings, can be classified as development co-benefits. Source: Tanner et al. 2015. Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 263 When developing plans and designing interventions towards coastal resilience, 7.9. 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Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 265 Mahfuzul Hasan Bhuiyan Bangladesh: 266 Enhancing Coastal Resilience in a Changing Climate Chapter 7: A Way Forward: Seven Recommendations for a More Resilient Coast 267Ismail Ferdous BANGLADESH: ENHANCING COASTAL RESILIENCE IN A CHANGING CLIMATE Coastal Bangladesh, home to over 40 million people, is a dynamic, unique, and thriving ability to continue the ongoing rapid economic growth hinges critically on how hazard environment full of opportunities and multiple risks. Sitting on the frontlines in the battle impacts are managed, and resilience is built into the economy and natural environment. against climate change, Bangladesh is among the most climate-vulnerable and disaster- prone countries in the world. The coastal zone of Bangladesh is experiencing setbacks The “Bangladesh: Enhancing Coastal Resilience in a Changing Climate” report seeks in its development because of natural hazard impacts. Tropical cyclones and riverine to provide actionable guidance for enhancing coastal resilience based on in-depth floods are frequently recurring events, while coastal and riverine erosion and saline analytical work. The work included extensive stakeholder consultations, field visits, intrusion are chronic phenomena affecting millions of people each year. Protecting lives, data analysis and modeling, with the aim of contributing to the design of sustainable livelihoods, and assets from disasters has been central to Bangladesh’s development climate-resilient coastal investments. The report provides evidence of the drivers of strategy, with the Government of Bangladesh headlining impressive progress in making risks in Bangladesh’s coastal region, what has been achieved so far in reducing these the coastal zone safer over the last several decades, highlighted by a hundred-fold risks, and the lessons learned from these achievements. The report explores innovative decline in fatalities from cyclonic events. Although significant development progress solutions illustrated with artist impressions and puts forward seven key cross-cutting has been made, as the coastal population and economy is expected to grow and the recommendations to move towards a more resilient coast, offering an opportunity to intensity and magnitude of extreme events is projected to increase due to climate strengthen the resilience of the coastal zone in the changing climate and build shared change, and hazard impacts still poses a great threat to the development ambitions of prosperity for decades to come. the country, further actions are needed to improve resilience of the coastal zone. The Bangladesh: 268 Enhancing Coastal Resilience in a Changing Climate