Photo by auntmasako/Pixabay
NATURE-BASED SOLUTIONS FOR
DISASTER RISK MANAGEMENT
Nature-based Solutions (NBS) that strategically conserve or restore nature to support conventionally
built infrastructure systems (also referred to as gray infrastructure) can reduce disaster risk and produce
more resilient and lower-cost services in developing countries. In the disaster risk management (DRM)
and water security sectors, NBS can be applied as green infrastructure strategies that work in harmony
with gray infrastructure systems. NBS can also support community well-being, generate benefits for
the environment, and make progress on the Sustainable Development Goals (SDGs) in ways that gray
infrastructure systems alone cannot.
Though NBS approaches have yet to be fully integrated into decision-making or to compel widespread
investment in developing countries, this is on the brink of change. Developing countries and their
partners (including multilateral development banks and bilateral agencies) are increasingly utilizing NBS
in DRM, as well as in water security, urban sustainability, and other development projects. The growing
number of NBS projects offer lessons and insights to help mainstream NBS into development decision-
making. As more disaster risk managers understand and integrate well-designed NBS into DRM projects,
more finance can be routed to nature-based projects that are cost-effective and resilient. With that goal
in mind, the World Bank’s Nature-based Solutions Program aims to facilitate uptake of NBS in water
management and DRM projects.
►► Guidance to support implementation of NBS in
DRM, including a high-level review of emerging
Contents policies and financing approaches that encourage
the use of NBS
Introduction 2
About the World Bank Nature-based
About the World Bank Nature-based Solutions Program
Solutions Program 3
Established in 2017, the World Bank NBS Program
Nature-based Solutions in the informs and enables the World Bank operational
Disaster Risk Management Portfolio 3
teams and clients to make use of natural and modified
Mitigating Disaster Risks with ecosystems for functional purposes, to reduce risks
Nature-based Solutions 6 associated with natural hazards and achieve other
Nature-based Solutions for development objectives.
Coastal Flooding and Erosion 7
WEBSITE: www.naturebasedsolutions.org
Nature-based Solutions for
Urban Flooding 9 PROGRAM OBJECTIVES
Nature-based Solutions The program seeks to inform and enable World Bank
for River Flooding 11 operational teams and clients to incorporate NBS
Enabling and Implementing considerations into project plans and investments by
Nature-based Solutions to
Manage Disaster Risk 13 ►► identifying NBS investments across the World Bank
portfolio;
Implementing Nature-based Solutions 14
►► addressing challenges and obstacles within the
Policy to Support Nature-based institution and in the client engagement process;
Solutions 15
►► mainstreaming NBS among clients, management,
Financing for Nature-based Solutions 18 and operational staff by providing technical
guidance and conducting pilot projects; and
References 21
►► fostering knowledge exchange among staff, and
with practitioners outside the World Bank.
This booklet is for staff at governments, development RELATED PUBLICATIONS
finance institutions (DFIs), and other development
The World Bank NBS Program has been exchanging
institutions to understand how NBS can enhance
knowledge, experiences, and lessons learned
DRM, and how to begin integrating these approaches
among stakeholders to enhance the planning and
into projects. The booklet illustrates NBS through 14
implementation of NBS across the World Bank
real-world examples. Its main findings draw on the
portfolio. Key resources include the following:
forthcoming report Integrating Green and Gray:
Creating Next Generation Infrastructure, published ►► Integrating Green and Gray: Creating Next
by the World Bank and World Resources Institute. The Generation Infrastructure (Browder et al.
booklet’s three sections cover the following: Forthcoming)1
►► The World Bank’s Nature-based Solutions Program ►► Implementing Nature-based Flood
and World Bank projects already investing in NBS Protection: Principles and Implementation
components Guidance (Available in English, Spanish, and
French) (World Bank 2017)2
►► Examples of NBS for three types of hazards: coastal
flooding and erosion, urban stormwater flooding,
and river flooding
2
►► Managing Coasts with Natural Solutions: projects that utilize NBS in project subcomponents
Guidelines for Measuring and Valuing the (Figure 1). The total value of subcomponents that
Coastal Protection Services of Mangroves utilize NBS is $2 billion (Figure 2). These projects
and Coral Reefs (World Bank 2016)3 target several hazards and risks (see Figure 3; note
►► The Role of Green Infrastructure Solutions some projects apply to more than one hazard).
in Urban Flood Risk Management (Soz et al.
2016)4 Six World Bank Global Practices have implemented
these projects with NBS components: Environment
Nature-based Solutions in the Disaster Risk and Natural Resources (35 projects); Social, Urban,
Management Portfolio Rural and Resilience (29); Agriculture (5); Water (5);
From 2012 to 2018, the World Bank’s DRM portfolio Social Protection and Labor (1); and Transport and
totaled US$52.87 billion across 681 projects. Over Information and Communication Technology (ICT)
this same period, the World Bank approved 76 DRM (1).
FIGURE 1 | Nature-based Solutions in the Disaster Risk Management Portfolio
30
25
Projects Approved
20
15
10
5
0
Africa and East Asia South Asia Latin America Europe and Global
Middle East and The Pacific and the Central Asia
Caribbean
Source: Adapted from WRI and World Bank (forthcoming)1.
FIGURE 2 | Investments in Project Components Containing Nature-based Solutions by Region
1000
800
US$ Millions
600
400
200
0
Africa and East Asia South Asia Latin America Europe and
Middle East and The Pacific and the Central Asia
Caribbean
Source: Adapted from Browder et al. (forthcoming)1.
FIGURE 3 | Hazards Targeted by Projects Containing Nature-based Solutions
35
Targeting Each Hazard
30
Number of Projects
25
20
15
10
5
0
Urban River Coastal Coastal Landslides Drought
Flooding Flooding Flooding Erosion and Erosion
Source: Adapted from Browder et al. (forthcoming)1.
Nature-based Solutions for Disaster Risk Management | December 2018 | 3
FIGURE 4 | Highlights of DRM Projects with NBS
The map below highlights some examples of DRM projects and their NBS components.
Poland
Morocco
Senegal
Vietnam
Suriname
Sri Lanka
Coastal & urban Coastal
River flooding Landslides
flooding erosion
L ATIN AMERICA & THE CARIBBE AN EUROPE & CENTRAL ASIA
Greater Paramaribo Flood Risk Management Odra-Vistula Flood Management Project
Location: Suriname Location: Poland
Challenges: Coastal & urban flooding; coastal erosion Challenge: River flooding
NBS: Mangrove restoration; rivers & floodplain management NBS: Dry polder & embankment retrieval
Cost of NBS-related Component: US$ 225,000 Cost of NBS-related Component: US$ 22M
AFRICA SOUTH ASIA
Stormwater Management and Climate Change Adaptation Project Forest-based Landslide Risk Management Program
Location: Senegal Location: Sri Lanka
Challenge: Urban & river flooding Challenge: Landslides
NBS: Artificial & natural retention ponds; wetlands NBS: Restoration of forests & vegetation
Cost of NBS-related Component: US$ 4M Cost of NBS-related Component: US$ 150,000
MIDDLE E AST & NORTH AFRICA E AST ASIA & THE PACIFIC
Integrated Coastal Zone Management Project Mekong Delta Integrated Climate Resilience and Sustainable Livelihoods Project
Location: Morocco Location: Vietnam
Challenge: Coastal & urban flooding Challenge: Coastal flooding & erosion; river flooding
NBS: Forests & vegetation; inland & coastal wetlands; dunes & beaches NBS: Mangrove restoration & re-connect river
Cost of NBS-related Component: US$ 4M Cost of NBS-related Component: US$ 243M
4
MITIGATING
DISASTER RISKS
WITH NATURE-BASED
SOLUTIONS
This section describes a variety of NBS that can help mitigate the impact
of coastal flooding and erosion, urban flooding, and river flooding. It
highlights risk-reduction potential, estimated costs of implementation
(where available), and examples of where and how NBS have been
used—drawing on experiences from the World Bank project portfolio as
well as other sources.
The magnitude of costs and benefits for nature-based solutions, and their
suitability for local contexts, vary widely according to geography, and
for several NBS very few estimates are available. This booklet provides
estimates from existing literature to give a sense of potential values, but
these estimates are not directly applicable to every site.
Nature-based Solutions for Disaster Risk Management | December 2018 | 5
NATURE-BASED SOLUTIONS ►► Coral and oyster reef systems can control
coastal erosion by reducing wave velocity. By one
FOR COASTAL FLOODING AND estimate, coral reefs reduce nonstorm wave heights
by 70 percent6. Median restoration costs for coral
EROSION reefs are $166/m2 (ranging from $2 to $7,500),
Average global flood losses in major coastal cities are while oyster reef restoration costs range from $107
to $316/m2.
expected to spike from $6 billion per year in 2005 to
$52 billion per year by 20505. Coastal flooding is on ►► Sandy beaches and dunes prevent coastal
the rise in part due to ecosystem degradation (e.g., erosion caused by strong winds, waves, and tides.
overextraction of natural resources, loss of wetlands They can also stop waves and storm surge from
reaching inland areas. The natural services these
and mangroves, and pollution that harms species), as
NBS provide can be enhanced through artificial
well as human settlement in low-lying coastal areas.
sand nourishment, which costs between $6,500 to
Climate change and sea-level rise are exacerbating
$16,400/meter (m)7. Revegetating and restoring
these trends. sand dunes can cost between $100 to $16,400/m.
NBS can help stabilize shorelines and attenuate waves ►► Seagrass helps stabilize sediment and regulates
to reduce flooding and erosion impacts. Integrating water currents that contribute to coastal erosion.
these solutions into coastal development and flood Seagrass beds reduce non-storm wave height 36
risk mitigation strategies could enhance overall flood percent on average6. A cost of $11/m2 (ranging
control system performance. from $0.20 to $410) is estimated for seagrass
restoration8.
►► Coastal wetlands, such as mangroves Additional benefits of NBS: In addition to
and salt marshes, can stabilize coastlines by
protecting coastlines from flooding and erosion, these
trapping sediment with their root systems, and by
NBS can generate income for local communities by
reducing wave height and velocity with their dense
underpinning fisheries, tourism, and recreation;
vegetation. Salt marshes can reduce nonstorm
wave heights by an average of 72 percent, and some nature-based solutions can aid in the storage of
mangroves, by 31 percent6. Median restoration freshwater supplies and improve water quality; they
costs for salt marshes are $1.11/square meter (m2) also enhance habitat and biodiversity. Intentional
(ranging from $0.01 to $33.00), and $0.1/ m2 for design of NBS to work in combination with gray
mangroves (ranging from $0.05 to $6.50). It can be infrastructure can achieve coastal resilience as well as
two to five times cheaper to restore coastal wetlands these additional benefits.
than to construct submerged breakwaters to deal
with wave heights of up to half a meter.
6 Nature-based Solutions for Disaster Risk Management | November 2018 | 6
Photo by Blue Forests/Flickr
Examples of NBS in Action
UNITED STATES | Oyster Reef Restoration9
Oyster reefs in the Gulf of Mexico have been degraded from decades of unsustainable harvesting, pollution, and diseases. The Nature
Conservancy has undertaken several reef restoration projects to rejuvenate oyster reefs and create a healthy marine ecosystem in
the Gulf that naturally protects the coastline while providing habitat, food, and cleaner waters. In Mobile Bay, Alabama, $3.5 million
has been spent on efforts to successfully restore 5.9 kilometers (km) of oyster reefs that have reduced wave height and energy of
average waves at the shoreline by 53 to 91 percent9. The reefs have also produced 6,560 kilograms (kg) of seafood per year—a weight
equivalent to half the total oysters harvested in Alabama in 2015. These efforts also help filter nitrogen pollution that contributes to
conditions that can be fatal for marine life.
THE NETHERLANDS | Sand Nourishment10
To help protect the Delfland Coast from erosion and inland flooding, the Dutch Government must periodically replenish sand along its
dunes and beaches. The traditional method for doing so, however, is costly—it requires small, frequent nourishment operations on an
as-needed basis. In 2011, the government took a different approach called the “Sand Motor.” With an investment of nearly $100 million,
it deposited a large volume of sand (21.5 million cubic meters [m3]) all at once to let the sand naturally distribute itself across the
coastline and replenish the natural sand dunes. Initial findings indicate the shoreline has indeed grown beyond the original deposit,
although the dunes have grown more slowly than expected10.
VIETNAM | Restoring Mangrove Forests11
In the late 1980s, rapid aquaculture expansion along the northern coast of Vietnam caused significant loss of mangrove forests, which
in turn decreased natural defenses against coastal floods and erosion in an area with a rapidly growing population. Recognizing
that the restoration of mangrove forests could help mitigate the impact of disasters and protect livelihoods, in 1994, the Vietnam Red
Cross launched the Mangrove Plantation and Disaster Risk Reduction Project to enhance existing gray infrastructure and reduce the
risk of flooding. By 2010, $9 million was invested to restore 9,000 hectares (ha) of mangroves along the shores of 166 communes as
well as 100 km of dike lines. Cost of damages to the dikes was reduced by $80,000 to $295,000, and $15 million was saved in avoided
damages to private property and other public infrastructure11.
VEGETATED DUNES AND SANDY BEACHES HELP ATTENUATE WAVES AND STABILIZE THE SHORELINE
Source: |vv@ldzen|/Flickr
Nature-based Solutions for Disaster Risk Management | December 2018 | 7
NATURE-BASED SOLUTIONS FOR ►► Bioretention areas, including rain gardens
and bioswales, are vegetated trenches designed
URBAN FLOODING to receive runoff in a specific location to help
control stormwater. A cost of cost between $110
Of the total global population, 68 percent will live in to $430/m2 is estimated for industrial bioswales17.
cities by 2050, up from 55 percent in 201812. Heavy In addition to controlling peak flows, bioretention
rainfall in low-drainage urban areas poses flood areas can filter pollutants and have been shown
hazards and overwhelms water infrastructure systems, to remove up to 90 percent of heavy metals from
resulting in system overflows that expose city residents stormwater16.
to health risks. As urban populations grow and climate ►► Open spaces such as parks and greenways
change shifts rainfall patterns, people are at increasing can be intentionally constructed or protected in
risk of urban flooding. Rapid urbanization often entails strategic locations to capture runoff from upstream
informal settlements in areas with high flood risk, such basins and adjacent areas. The cost of open spaces
as floodplains and riverbanks, exposing the urban poor is highly variable and largely dependent on land
prices. The benefits can be substantial: a study of
to higher risk of floods.
green spaces in Beijing, China, showed that these
NBS for urban flooding can help increase onsite areas stored 154 million m3 of rainwater, which
stormwater absorption. They can be applied from corresponds roughly to the annual water needs of
the house or building level to landscape scale, are the city’s urban ecological landscape18.
often used in combination with multiple NBS and ►► Constructed wetlands can capture and retain
gray infrastructure components, and are most stormwater, allowing for greater water infiltration.
effective when integrated into comprehensive urban The cost of constructed wetlands may range from
development plans. $7 to $15/m2 and are usually less expensive than
built (gray) options for the same function, though
►► Green roofs reduce stormwater runoff by these costs are also highly variable according to
promoting rainfall infiltration on the tops of land costs19. An acre of wetland can store 3.8 to 5.7
buildings. Green roofs retain 50 to 100 percent of million liters of floodwater, reducing the peak load
the stormwater they receive13. At $110 to $270/m2, on built stormwater and wastewater systems.
green roofs are more than two to five times more
Additional benefits of NBS: Beyond helping
expensive to install than traditional roofs. However,
control urban flooding and preventing stormwater
they are of comparable cost over their life cycle,
pollution, these NBS create additional benefits for
given that green roofs typically last twice as long as
traditional roofs, and they also insulate buildings, urban communities. For example, urban green spaces
which cuts heating and cooling bills14. have been shown to increase property values by 5 to
15 percent, while wetlands create birdwatching and
►► Permeable pavements are pervious concrete,
recreation opportunities20. Many of these NBS mitigate
asphalt, or interlocking pavements that allow
the heat island effect and provide a cool refuge for city
rainwater to infiltrate where it falls, thereby
reducing stormwater runoff. At $5 to $100/m2, dwellers and wildlife.
installation costs are roughly two to three times
higher than for regular asphalt or concrete15.
However, some applications have demonstrated a
90 percent reduction in runoff volumes16.
8
Examples of NBS in Action
SRI LANKA | Urban Wetlands21
Metropolitan Colombo is surrounded by large, interconnected natural and managed wetlands that help retain floodwaters. However, rapid
urbanization in recent decades has caused steady wetland degradation, and a 30 percent reduction in wetlands’ water-holding capacity. In
2010, the city experienced a series of record-breaking flooding events that brought unprecedented economic losses. To reduce flood risks, the
Government of Sri Lanka implemented the Metro Colombo Urban Development Project, which combines green and gray infrastructure—wetland
conservation, flood retention parks, and traditional concrete bank protection walls. The integration of wetlands and flooding parks allows
rainwater to infiltrate slowly, decreasing the volume of water that must be moved through the overtaxed built system. Economic analysis has
found, the more wetlands are conserved, the greater the payoff in flood protection and other benefits, like wastewater treatment21.
UNITED STATES | Mixing Multiple NBS for Urban Stormwater Management22, 23, 24
One-third of Portland, Oregon, has a combined sewer system that transports its stormwater runoff and sewage to treatment using a single pipe.
Over time, Portland grew, and the system struggled to handle the growing volumes of sewage and stormwater runoff from impervious surfaces,
resulting in increased frequency of combined sewer overflows (CSOs) that directly affected water quality and community health. From 1990 to
2011, the City implemented a CSO control program that expanded gray infrastructure, like tunnels and treatment facilities, to reduce its CSOs and
clean up local waterways22. As a complement to this program, the City also implemented a range of programs, policies, and incentives to spur
the use of urban NBS to help keep stormwater out of combined sewers and control overflows, such as its Green Streets program. Since 2007, the
program has installed permeable pavements and bioswales throughout the city and achieved an 80 to 94 percent reduction in peak flow in the
targeted areas23. Portland officials estimate $9 million in their total NBS investment portfolio has yielded a savings of $224 million in CSO costs
related to repairs and maintenance24.
CHINA | Promoting Public-Private Partnerships to Scale Up Urban NBS25
China’s rapidly growing urban population has increasingly encountered serious water challenges associated with insufficient water infrastructure,
sprawling development, degradation of waterways, and intensifying storms: in fact, 62 percent of cities experience flooding, and half are
considered water-scarce. To address these growing hazards, the Chinese Government is supporting the development of “sponge cities” by
providing funding and technical support to cities to implement NBS to capture, store, filter, and purify rainwater for reuse. Between 2015 and
2016, the government supported 30 cities, which have constructed green roofs, permeable pavements, and wetland restoration25. The central
government is directly providing between $59 and $88 million per year to each of its 30 pilot cities for three consecutive years as start-up capital
to help them devise and construct NBS. This investment is intended to inspire the creation of public-private partnerships (PPP) that will unlock
private finance to meet overall investment needs25. China’s Ministry of Finance created a strategy to support the PPP model by soliciting private
investment in construction projects and formalizing the government procurement process for PPPs25.
RESTORED URBAN WETLANDS AT THE BEDDAGANA WETLAND PARK, SRI LANKA
Source: World Bank
Nature-based Solutions for Disaster Risk Management | December 2018 | 9
NATURE-BASED SOLUTIONS FOR ►► Stream beds and banks can help slow the
river flow when natural functions are preserved
RIVER FLOODING or restored, such as a river’s meandering path
or vegetated riparian areas. This can sometimes
River flooding is a common natural process that is require removing concrete reinforcements
and revegetating riverbanks or riparian areas.
essential for productive river-floodplain ecosystems. It
Restoration costs can vary widely: channel
also poses serious hazards as population growth and
rehabilitation costs range from $16,000 to
economic development in flood-prone areas continue
$53,000/km of river30. The benefits can be
to rise. Climate change and aging flood-management substantial: for example, setting back levees along
infrastructure only compound the risk. Economic the Middle Mississippi River in the United States
losses from river floods have increased by 6 percent would decrease expected annual damages by 55
per year on average since the 1960s26. percent in urban areas31.
Integrating NBS into flood control systems can ►► Upland forests with deep soils can help slow
and retain runoff, resulting in lower peak flow.
complement engineered infrastructure and relieve
Forest management is most effective at retaining
pressure on the system, and is especially effective at
and slowing moderate floods of short duration
mitigating impacts of short-duration floods. NBS for
before soils become saturated32.The cost of forest
river flood risk mitigation often involve large-scale restoration (excluding land acquisition costs) varies
interventions, and therefore must be carefully planned but is on average between $2,000 and $3,500/
to meet the needs of affected communities. ha29. A review of restoration studies found that
82 percent reported a decrease in peak flow after
►► Floodplains and bypasses can store and
restoring upland areas33.
slowly convey water and sediment that overtops
riverbanks during flood events. Bypasses comprise Additional benefits of NBS: Along with reducing
built diversions, like weirs, to control floodwater flooding risks, NBS implemented along rivers can have
volume, while floodplains are naturally occurring a range of additional benefits for both people and the
areas that absorb water. The cost of restoring and natural environment. Restoring riverbanks and flood
reconnecting floodplains varies with land prices, plains can improve downstream water quality and
roughly $10,000 to $800,000/ha in Europe27. provide important fish and migratory bird habitats34.
►► Inland wetlands can reduce flood risk by storing Slowing down flood waters in river basins can also
water during wet periods and releasing it during increase the deposits of nutrient-rich sediments that
dry periods. Their storage capacity depends on help to create fertile soils for agriculture35.
the type of wetland and its location, but some can
store up to 9,400 to 14,000/m3 of floodwater per
hectare28. Estimated costs of wetland restoration
are $33,000/ha 29.
10 Photo by U.S. Army Corps of Engineers/Flickr
Examples of NBS in Action
POLAND | Remeandering Rivers36
In response to a series of catastrophic river flooding events in 1997, 2006, and 2010, the Polish Government and the World Bank imple-
mented two hybrid NBS projects in the Odra and Vistula River basins. These projects take a systems approach that make investments to
deliver flood protection services to the entire population by protecting the country’s robust economic centers, as opposed to standalone
interventions that only benefit the local community. A range of project components are being implemented that combine existing gray
infrastructure with natural features in the river basin. For example, expanding the river floodplain by retrieving embankments and improv-
ing existing levee systems and drainage canals helps enhance flood retention capacity and lower peak flooding levels in upstream areas.
These efforts not only protect the immediate rural communities, but also the large economic and urban centers downstream36.
UNITED STATES | Bypassing Floodwaters37, 38
Major flooding events in the late 1800s in California’s Sacramento Valley brought realization to communities and policymakers that exist-
ing single-channel, gray infrastructure approaches to flood management were insufficient to handle the volume of floodwaters in the re-
gion. At the turn of the century, opinions shifted in support of the implementation of a comprehensive, multichannel flood-control system.
The resulting system is known today as the Sacramento River Flood Control Project and consists of a network of built levees and weirs,
and natural bypasses that work together to route and control floodwaters from the main river channel to protect settlements along the
river valley. The Yolo Bypass, for example, is an integral part of the hybrid NBS network, and receives overflow from the Sacramento River
through weirs. The bypass consists of 240 km2 of wetland area (65 km long); during large storm events, it conveys as much as 80 percent
of floodwaters37. It also provides groundwater recharge, fosters wildlife habitat, and serves as agricultural land when not flooded38.
CHINA | River Reconnection39
Widespread dam and dike construction in the Yangtze River Basin from the 1950s to 1970s fragmented the existing river-lake wetlands
system. The fragmentation contributed to major flooding events that occurred in the 1990s, which resulted in thousands of deaths and
billions in direct economic losses. To mitigate future flooding risks, the Chinese Government in partnership with the World Wildlife Fund
(WWF) reconnected the Yangtze River with the disconnected lakes and rehabilitated the natural functions of the wetland system39.
The reconnection project restored 448 km2 of wetlands, which have a floodwater retention capacity of 285 million m3. In one of the lake
districts, the restoration of seasonal flooding increased fisheries production more than 17 percent39. Reconnecting the river-lake wetland
system has helped reduce vulnerability to flooding and to increase wildlife populations.
VIEW OF THE YOLO BYPASS IN CALIFORNIA’S SACRAMENTO VALLEY DURING A FLOOD EVENT
Source: Pacific Southwest Region USFWS/Flickr
Nature-based Solutions for Disaster Risk Management | December 2018 | 11
ENABLING AND
IMPLEMENTING
NATURE-BASED
SOLUTIONS TO
MANAGE DISASTER
RISK
The previous section covered the variety of NBS that can be utilized to
address development challenges and disaster risk, and highlighted their
many advantages—they can be cost-effective, multifunctional, resilient,
and they can empower communities. Yet, to date, the mixed success of
NBS projects has revealed that these advantages may not be realized
unless NBS is well-designed and efficiently implemented. Mainstreaming
natural infrastructure into development decisions requires an expansion
of high-quality demonstration projects as well as documentation of their
results.
12
IMPLEMENTING NATURE-BASED Technical dimensions
NBS can be functionally equivalent to gray
SOLUTIONS ►►
infrastructure components. The performance of
NBS in meeting a service provision target can be
Lessons from existing NBS projects and guidance estimated through modeling.
documents help demonstrate best practices for
►► NBS can have variable service provision, large
assessing, designing, and managing NBS projects. The uncertainties, and possible failures, requiring
World Bank (2017) guide Implementing Nature-based thoughtful pairing and sequencing of infrastructure
Flood Risk Mitigation sets out eight steps for the components to ensure resilience in a changing
successful implementation of NBS for river flooding, climate.
with relevance to a broad set of NBS (see Figure 5, ►► NBS project viability depends on the willingness
page 14). The World Resources Institute and World and capacity of impacted communities to operate
Bank’s, forthcoming report, Integrating Green and the NBS or at least to work in harmony with it.
Gray: Creating Next Generation Infrastructure,
►► Identifying key features of the target landscape—
also offers high-level guidance to support design and
from ecosystem services and biodiversity to
implementation of successful NBS. interdependencies with other ecosystems, people,
and infrastructure—provides baseline information
to help ensure interventions reconcile conservation
Integrating NBS considerations into
and development needs without harming biological
development planning or cultural diversity, ecosystem services, or people
Normal planning processes offer opportunities to and their livelihoods.
define suitable roles for NBS to work in harmony with Social dimensions
conventional DRM project components, such as gray
►► The main operators of NBS are often local
infrastructure, for example:
communities, responsible for implementing land
►► Regional or sectoral planning processes: stewardship practices, and for maintaining the
land-use master plans, coastal zone plans, forest project over the long term. NBS employ strategies
management plants, country- or state-level water that impact land management, often across a
resources plans, and river basin plans can be used landscape and across property boundaries or
to identify potential opportunities for NBS. jurisdictions. For this reason, NBS sometimes
impact more people than gray infrastructure
►► Infrastructure master planning: Potential
projects do, and often impact multiple stakeholder
NBS investments can be considered in the menu
groups.
of options to inform investment programs and
financial needs. ►► In certain situations NBS approaches may empower
communities more than gray infrastructure does,
If NBS opportunities can be confirmed at these early by building communities’ capacity to shift their
stages of planning, then resources can be directed natural resource practices toward more sustainable
to undertake detailed feasibility and design studies, paradigms. To capture these opportunities, NBS
explicitly considering linkages with gray infrastructure. should be assessed with systemwide analysis
of the local socioeconomic, environmental, and
Assessment of projects with NBS (and green institutional conditions.
infrastructure) components
Economic dimensions
Conducting thorough assessments can help identify
►► NBS can be low-cost, and cost-effective, helping
the right places to apply NBS, as well as inform the
enhance the cost-benefit ratio of development
design of NBS. Key considerations for assessment,
projects with NBS components.
design, and implementation of NBS include the
following:
Nature-based Solutions for Disaster Risk Management | December 2018 | 13
►► Economic analysis will undervalue the worth The assessment and design needs of NBS may require
of NBS if the chosen analytical methods do not different expertise, time, or resources than typical
appraise NBS’s delivery of important cobenefits, DRM projects. Making use of project preparation
which can be both monetary and nonmarket. facilities can help ensure successful NBS assessment
►► While NBS can in theory generate multiple and design. Bilateral donor agencies can encourage
benefits that help resolve social inequalities, development bank adoption of NBS by creating NBS
they must be consciously designed to do so in project preparation and monitoring facilities.
practice. Evaluating who stands to gain from NBS,
evaluating trade-offs, and incorporating adequate
benefit-sharing schemes are therefore also critical
components of NBS economic assessment.
FIGURE 5 | Steps to Successful Implementation of NBS
1 2 3 4
DEFINE PROBLEM, PROJECT DEVELOP FINANCING CONDUCT ECOSYSTEM, DEVELOP NATURE-BASED RISK
SCOPE, AND OBJECTIVES STRATEGY HAZARD, AND RISK ASSESSMENTS MANAGEMENT STRATEGY
■■ Document stakeholder ■■ Create preliminary ■■ Map current and future hazard risk, ■■ Review feasible measures to
needs budget for project exposure and vulnerability reduce risk, their estimated
effects and implementation
■■ Map areas of interest ■■ Review available ■■ Review land use, ecosystem
steps
depicting main risks and and possible future presence, and health
root causes to these risks resources ■■ Outline different strategies, their
■■ Define importance of ecosystem
phasing in time with a focus
■■ Define measurable project for DRR
on no-regret and less costly
objectives
options first
5 6 7 8
ESTIMATE THE COST, BENEFITS SELECT AND DESIGN THE MONITOR AND INFORM
IMPLEMENT AND CONSTRUCT
AND EFFECTIVENESS INTERVENTION FUTURE ACTION
■■ Complete cost-benefit analysis ■■ Design NBS, and ■■ Determine lifetime of ■■ Review monitoring
including the full range of create monitoring plan intervention, support reports
social and environmental containing indicators, regulatory frameworks
■■ Take needed action to
benefits/impact target, values, roles and to sustain and maintain
change or improve the
responsibilities intervention
planet
■■ Define monitoring ■■ Construct NBS ■■ Share lessons learned
method and duration
■■ Establish maintainence
plan
Source: World Bank 20172.
14
POLICY TO SUPPORT NATURE- ►► Creating incentives for local actors to
participate in NBS. This can include aligning
BASED SOLUTIONS public incentives with local or privately led NBS
efforts to maximize the benefits of these efforts; as
One key to successful NBS implementation well as establishing national payment for ecosystem
service programs or land acquisition programs for
is understanding the institutional and policy
NBS.
environment that creates enabling conditions for
NBS. In many cases, NBS can be used as one approach ►► Authorizing and enabling NBS and allowing
to achieve policy objectives on DRM and on other for regulatory flexibility. Governments can
signal that NBS can be used to comply with
issues, including climate mitigation, water security, air
environmental requirements of building codes,
quality, and public health. Development of robust and
water safety regulations, and environmental
effective policy frameworks that create a role for NBS
impact mitigation plans. This includes using NBS
are essential for implementing high-quality NBS, as to achieve climate mitigation and adaptation
well as for catalyzing larger-scale NBS adoption. objectives, air quality and public health objectives,
and the like. Similarly, governments can allow
A growing number of international agreements, like
green infrastructure to be counted as a capital asset
the Paris Agreement, High-Level Panel on Water, Sus-
on the balance sheet for the services it provides.
tainable Development Goals, and Sendai Framework
for Disaster Risk Reduction, all include high-level ►► Encouraging or requiring consideration of
NBS by decision-makers. Integrating NBS into
commitments to promote ecosystem-based solutions
planning often involves guidance or policy, such
such as NBS. These commitments are intended to filter
as providing criteria for infrastructure projects
down to actions at the country level, creating a window
to include NBS evaluations in the planning, or
for policy changes. For example, among signatories of adopting building codes or zoning laws that require
the Paris Agreement, 102 countries have now com- a portion of space dedicated to green elements.
mitted to restore or protect nature as an adaptation
►► Supporting monitoring, research, and
measure in their nationally determined contributions
innovation on NBS through government-
(NDCs)40. NBS were most commonly mentioned in sponsored research and data collection programs.
NDCs of low- and lower-middle-income countries. Collecting baseline data on ecosystem health and
following trends in environmental degradation, like
The following types of policies and government actions
deforestation and drought, as well as in restoration
can help create an enabling environment to integrate
makes it easier to determine the suitability of NBS
NBS into DRM and other development strategies1,41: in meeting local needs and priorities, as well as to
►► Incorporating sustainable landscape vision monitor NBS project impacts and promote mutual
into strategies and policies. A high-level vision learning among projects.
can help mediate traditional conflicts between
economic growth and conservation interests, and
identify strategic opportunities to deploy high-
quality NBS. Land-use planning can help create a
shared vision of the multiple goals of sustainable
landscapes and help embed that vision into relevant
jurisdictional strategies.
Nature-based Solutions for Disaster Risk Management | December 2018 | 15
►► Facilitating cross-sector coordination. NBS land value capture, water tariffs, and insurance.
often cross jurisdictions; their implementation Financing mechanisms for NBS is discussed further
can also benefit multiple sectors and agencies, and in the following section.
contribute toward a broad range of policy objec-
Importantly, many of the policies explicitly supporting
tives. To operationalize NBS, governments should
NBS have only been in place for a short period of time,
promote interagency coordination to ensure NBS
and some have yet to be implemented; thus, only very
do not incur red tape. Governments can grant legal
authority to DRM agencies to implement cross-sec- few policies have been rigorously tested and proven
tor NBS to engage water, energy, and agriculture effective. Although there is no perfect formula for NBS
sectors, among others, in NBS projects. At the policy, a growing number of states and countries have
same time, governments can link NBS to existing made progress that can serve as examples to others.
policy objectives such as climate mitigation, adapta- Development agencies can help encourage policy re-
tion, infrastructure, and water security. form along these lines by leveraging policy lending and
►► Creating financing mechanisms to unlock engaging in dialogue with clients.
investment in NBS. Governments can earmark
public funds for explicit use in NBS, or set policy
that generates funds from other sources, such as
16
Examples of NBS in Action
PERU | Raising Revenue from Water Tariffs for Resilient NBS42
Peru has dealt with water crises related to El Niño for centuries, and climate change is only exacerbating these water woes. Recognizing
this increased risk, in 2016, Peruvian lawmakers passed the Sanitation Sector Reform Law, which requires water utilities to earmark revenue
from water tariffs for watershed conservation and climate change adaptation, and to consider these strategies in the official budgeting and
planning processes. This policy change has already generated $30 million for NBS via payments for ecosystem services, and an additional
$86 million for climate change mitigation and disaster risk management42.
UNITED STATES | Recognizing NBS as Infrastructure at the State-Level43, 44, 45
Over the past 30 years more than 5 million hectares of land in the American West have burned due to wildfires, including import-
ant watersheds that are becoming degraded with the loss of trees and increased erosion43. In 2016, California passed a law that
classified source watersheds as integral components of water infrastructure. This makes it easier for utilities to justify investments
in watershed health as a means for combatting wildfires that can damage water infrastructure and threaten water supplies. The law
allows for investment in NBS to support source watersheds using the same forms of financing typically reserved for gray infrastruc-
ture44. This policy change may motivate investments from utilities and other beneficiaries, as well as the state, in watershed health.
One such project is the Forest Resilience Bond, which utilizes investor capital and cost-sharing among beneficiaries, like water
utilities, to pay for benefits created by restoration activities and decrease the risk of severe wildfires45.
COMMUNITY MEETING IN MKURANGA DISTRICT, TANZANIA
Source: Roots, Tubers and Bananas/Flickr
Nature-based Solutions for Disaster Risk Management | December 2018 | 17
FINANCING FOR NATURE-BASED water management through ecosystem-based
adaptation and through their support of natural
SOLUTIONS systems increasing resilience in coastal areas47.
Only a small sliver of these funding sources are
Increased uptake of NBS depends on rerouting
dedicated to disaster risk reduction, and an even
or unlocking new funds to support these projects.
smaller amount of these funds are currently put
Presently, most NBS are funded through public
toward NBS. That is now changing with the creation of
and philanthropic means. These will continue to be
new funds and utilization of financing mechanisms for
important sources of funding, but these alone are
NBS.
not enough to meet the worldwide NBS investment
opportunity. A variety of new financing approaches The Green Climate Fund (GCF) is one example.
and mechanisms have emerged to blend public and The GCF was created under the UN Framework
private finance together to enable broader adoption of Convention on Climate Change (UNFCCC) to provide
NBS. grants, loans, equity, or guarantees to finance climate
change mitigation and adaptation measures in
In designing NBS projects, task team leads and project
developing countries. So far, $10.3 billion has been
developers can take advantage of the following existing
pledged, $3.5 billion committed, and $1.4 billion
and emerging sources of funding for NBS. The choice
invested in 74 projects. The GCF has already funded
of which funding mechanism to use should be guided
a handful of projects with NBS components; it judges
by suitability for local context and the degree to which
projects on their ability to avoid infrastructure and
NBS will generate cash flows.
development lock-in, to reduce vulnerability and
International public finance opportunities exposure to climate risks, and to generate multiple
environmental benefits, among other criteria. The GCF
for NBS aims to leverage private sector contributions and to
International public finance and development aid support development of new markets48.
are a primary source of available funding for NBS
in developing countries. These include multilateral Other applicable international development aid
funds, multilateral development banks (including approaches include pay-for-success models (also
the International Bank for Reconstruction and known as pay-for-performance), where loan
Development [IBRD] and the International disbursements are made against actual results
Development Association [IDA]), and bilateral sources irrespective of any contractual arrangements. A debt-
like national development or aid organizations. for-nature swap is another financing mechanism
that can support NBS and is particularly helpful for
International public finance for NBS often takes developing countries with a large national debt and
the form of standard project financing where loan threatened natural ecosystems. The debt is canceled
disbursements are made against payments to contracts or restructured if a country agrees to invest in
as well as grants. The Global Environmental environmental protection measures.
Facility (GEF), created in 1992, has supported
NBS through investment in a wide range of projects Domestic public finance opportunities
that advance, for instance, integrated water resource for NBS
management, the restoration of degraded lands,
Local and national governments often support NBS
and special designation of protected areas46. The
through dedicated taxes, fees, and charges that
GEF Adaptation Fund was created in 2008 and has
make up general revenue funds can be drawn upon
committed $517 million to projects in developing
to finance programs that invest in NBS, and can be
countries that are particularly vulnerable to climate
specifically earmarked for investment in NBS-related
change. This Fund has enabled NBS by promoting
18
projects. Much of these public funds are related to ►► Green Bonds: Also known as blue, climate, and
environmental objectives. For example, revenue from environmental bonds, these make up a growing
compensatory mitigation and compensation market ($157 billion in green bonds issued in
fees imposed on unavoidable impact to water is 2017). The new Water Infrastructure Standard of
collected in 57 countries49. These funds can be routed the Climate Bonds Initiative (CBI) enables water
projects—including projects that utilize green
to support NBS for water security or DRM projects: in
infrastructure—to be certified as green bonds. This
the United States, compensatory mitigation generates
provides an avenue for nature-based solutions to
$3.8 billion a year, which is then used to support
attract private financing, while also allowing cities
restoration of watershed areas50. Municipal bonds to communicate with corporations and investors
are another useful policy driver that allow government interested in green growth53.
entities to borrow money from investors and repay
►► Insurance Payments for Risk Reduction:
it over time using tax revenue or other collateral.
Also known as catastrophe bonds, these provide
Municipal bonds can be used to provide upfront
financial protection in the event of disaster, such
capital quickly, which can be used as seed funding for as intense storms and floods. In 2018, insurance
NBS. brokerage Willis Towers Watson launched the
Global Ecosystem Resilience Facility (GERF) to
Federal or local public infrastructure spending
support coastal communities in the Caribbean54.
as well as disaster risk mitigation programs
GERF uses risk pooling and other financial
can also be routed to green infrastructure strategies instruments like catastrophe bonds, resilience
that help meet flood control standards, though the bonds, grants, and loans to provide support to local
vast majority of these funds currently go toward communities.
conventional infrastructure.
►► Pay-for-success models: Public and private
lenders can utilize pay-for-success, environmental
Emerging sources of funding and impact bonds, or conservation impact bonds, to tie
financing approaches payment for service delivery to the achievement
Because NBS can sometimes address multiple of measurable outcomes. This approach rewards
development objectives, it is possible to generate investors based on how well the NBS performs. One
such example of said model is the DC Water Bond,
multiple cash flows, thereby attracting a diverse base
discussed in more detail below.
of investors interested in different project benefits.
This includes mission-focused investors willing to ►► Corporate stewardship models: Corporations
tolerate higher risk or lower returns, who can leverage are increasingly realizing the importance of
understanding the impact of their business on
their investment to “de-risk” NBS investments for
the environment and incorporating sustainable
less confident investors. A variety of financing models
practices that improve company reputations,
has been introduced to make NBS bankable and to
offset negative environmental impacts, safeguard
appeal to commercial interests. While private sector valuable natural assets, and make businesses more
investment in NBS is still relatively small compared profitable. One Coca-Cola program aims to provide
to public funding sources, these models are gaining water replenishment benefits equal to 100 percent
momentum. They include, as follows: of the water used in its global sales by 202053. It
first met its goal in 2015, and continues to do so
►► Water Funds: These pool money from multiple
through source water protection activities like
water-dependent private and public sector
watershed restoration, and through replenishment
actors so that each small contribution enlarges
programs like improved wastewater collection and
the cumulative impact. There are more than 25
treatment54.
Water Funds in Latin America and the Caribbean
that have routed about $120 million to invest in
watershed management51. A review of 16 of these
Water Funds found that 12 report regulating water
flows, either to increase water availability or to
reduce flood risk, as their primary objectives52.
Nature-based Solutions for Disaster Risk Management | December 2018 | 19
EXAMPLES OF NBS IN ACTION
SEYCHELLES | Debt Restructuring for Protected Marine Areas55
In 2008, Seychelles defaulted on its national debt and has since sought ways to preserve its natural environment—the vital pillar
of its economy and of its citizens’ livelihoods—without endangering financial stability. In 2015, The Nature Conservancy and its
impact-investing unit, NatureVest, brokered a deal to restructure a portion of Seychelles’ debt with a debt-for-nature swap. The
deal allows the government to restructure the country’s debt with a mix of investments and grants, in exchange for designating
one-third of its marine area as protected. The agreement frees capital streams and directs debt service payments to fund climate
change adaptation and marine conservation activities that will improve the management of Seychelles coastlines, coral reefs, and
mangroves55. This is the first time this financing technique has been used for the marine environment.
PHILIPPINES | National Fund for Climate Disasters56
The Philippines People’s Survival Fund (PSF) is a national fund dedicated to supporting disaster risk reduction and climate change adapta-
tion projects at the local level. The Philippine Congress enacted the PSF in 2012 in response to the country’s vulnerability to climate-related
disasters and the need for additional support at the community level. The government allocates $20 million of general revenue to the PSF,
which can also be supplemented through the mobilization of additional funding sources like local governments or the private sector56. The
PSF is managed by a board comprising six governmental and three nongovernmental representatives that evaluate project proposals for
funding. Once approved, funds are disbursed under a memorandum of agreement with monitoring and reporting requirements. The PSF
provides long-term financing streams to support projects proposed by local government units or accredited community organizations.
UNITED STATES | Pay-for-Success Model for Urban Green Infrastructure57
To better manage stormwater and prevent urban flooding, Washington, DC’s water utility, DC Water, boldly pursued an unconventional
financing structure to pay for its NBS program. DC Water utilized a performance-based or “pay-for-success” financing model issued as a
30-year, tax-exempt municipal bon57, a contract between a public entity (i.e., DC Water) and private investors, where payment is based on
measured environmental outcomes. The NBS program employs different types of hybrid infrastructure to minimize urban hazards, including
bioretention or rain gardens; permeable pavements; and downspout disconnection, which reroutes drainage pipes into rain barrels or
pervious surfaces57. This financing mechanism is the first of its kind for NBS in the United States.
Source: Nijmegen/Wikipedia
20
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ACKNOWLEDGMENTS
This booklet was prepared by a team from the World Bank and World Resources Institute, led by Suzanne Ozment, Gretchen Ellison, and Brenden
Jongman with support and input from Simone Balog-Way, Stefanie Kapua, Russell King, Denis Jordy, and Boris Van Zanten. It was made possible with
support from the Global Fund for Disaster Reduction and Recovery (GFDRR) and the Program for Forests (PROFOR). We also thank Rebecca Carter, Indira
Masullo, and John-Rob Pool from WRI for their review and comments and Billie Kafner, Shazia Amin, and Carni Klirs for the production of this document.
The booklet draws on the forthcoming report Integrating Green and Gray: Creating Next Generation Infrastructure, published by the World Bank and World
Resources Institute.
For more information, visit www.naturebasedsolutions.org.
CONTACTS:
Brenden Jongman bjognman@worldbank.org
Denis Jean-Jaques Jordy djordy@worldbank.org
Boris Van Zanten bvanzanten@worldbank.org
Nature-based Solutions for Disaster Risk Management | December 2018 | 23