Title page
Contents
ACKNOWLEDGMENTS 2
FOREWORD 5
EXECUTIVE SUMMARY 7
WHY INTEGRATE GREEN AND GRAY INFRASTRUCTURE? 17
Today's Infrastructure Development Challenges 18
Needs for Mainstreaming Green-Gray Infrastructure 23
Why the World Bank Is Integrating Green and Gray Infrastructure 24
About This Report: A Framework to Integrate Green Infrastructure 26
IMPROVING SERVICE DELIVERY WITH GREEN INFRASTRUCTURE 31
Identifying Green Infrastructure Opportunities in Planning Processes 33
Assessing Technical Performance 37
Assessing Cobenefits and Environmental Impact 40
Understanding and Managing Uncertainty 41
Monitoring and Evaluation 42
THE SOCIAL FOUNDATION OF GREEN INFRASTRUCTURE 45
Water Service Providers Need Government and Civil Society Support 48
Harnessing Cobenefits to Enhance Social Well-being 49
Establishing Social Safeguards 51
Promoting Social Inclusion 52
THE ECONOMICS OF GREEN INFRASTRUCTURE 55
Estimating Green Infrastructure Costs 58
Standard Cost-Effectiveness Analysis for Green Infrastructure 59
Beyond Cost-Effectiveness Analysis 60
CREATING NEW FINANCING OPTIONS WITH GREEN INFRASTRUCTURE 65
Infrastructure Finance Models 66
Green Infrastructure Investment Levels 68
Public Finance 69
Private Finance 71
Development Partner Finance 73
Philanthropic Funds and Grants 75
ENABLING POLICIES FOR EFFECTIVE GREEN INFRASTRUCTURE 77
Proactive Government Support Is Essential 78
Examples of Enabling Policies and Programs 79
General Principles for Governments 81
Role of Development Partners 83
THE WAY FORWARD 85
Looking Ahead: Learning New Lessons and Closing Knowledge Gaps 87
APPENDIX A: SERVICES THAT CAN INTEGRATE GREEN INFRASTRUCTURE AND RELATED CASE STUDIES 89
1. WATER SUPPLY AND HYDROPOWER 90
Case Study 1A. Payments for Ecosystem Services to Support Hydropower Operations in Costa Rica 92
Case Study 1B. Targeted Green Infrastructure for Source Water Protection in Brazil 94
2. COASTAL FLOOD MANAGEMENT AND EROSION CONTROL 96
Case Study 2A. Piloting Mega Sand Nourishment for Coastal Flood Management in the Netherlands 98
Case Study 2B. Using Mangroves and Sea Dikes as First Line of Coastal Defense in Vietnam 100
3. RIVER FLOOD MANAGEMENT 102
Case Study 3A. Integrating Green and Gray Infrastructure for River Flood Management in the United States 104
Case Study 3B. Combining Green and Gray Infrastructure for Flood Risk Management at the River Basin Scale in Poland 106
4. URBAN STORMWATER MANAGEMENT 108
Case Study 4A. Innovative Financing for Urban Green Infrastructure in the United States 110
Case Study 4B. Conserving Wetlands to Enhance Urban Flood Control Systems in Sri Lanka 112
5. DROUGHT MANAGEMENT 114
Case Study 5A. User-financed Ecosystem Conservation for Water Security in Ecuador 116
Case Study 5B. Recharging Aquifers to Combat Drought in Somalia 118
6. AGRICULTURE, IRRIGATION, AND DRAINAGE 120
Case Study 6A. Community-led Watershed Restoration in India 122
Case Study 6B. Active Soil Management for Water Conservation in China 124
APPENDIX B: REFERENCES ENDORSING GREEN INFRASTRUCTURE AND SIMILAR APPROACHES 126
REFERENCES 129
Table 1.1. From the Frontlines: Green Infrastructure Case Studies Tackling Multisector Water and Disaster Risk Challenges 29
Table 2.1. Issues to Include in Green Infrastructure Technical Assessment, Examples by Service 32
Table 2.2. Tools for General Identification of Green Infrastructure Opportunities 36
Table 2.3. Tools for Technical Analysis of Proposed Green Infrastructure Projects 38
Table 3.1. Engaging Communities: Key Social Issues by Type of Intervention 46
Table 4.1. Potential Cost Reductions and Economic Cobenefits Associated with Green Infrastructure 57
Table 4.2. Cost Categories for Infrastructure 58
Figure 1.1. Green Infrastructure Is a Subset of Natural Capital and Nature-based Solutions 19
Figure 1.2. Dramatic Rise in Economic Losses Due to Flooding 20
Figure 1.3. Green Corridors Prevent Diffuse Pollution from Agriculture 22
Figure 1.4. The Poor Are the Most Vulnerable to Climate Change 25
Figure 1.5. Rain Gardens and Other Green Infrastructure Reduce Urban Stormwater and Flood Events 26
Figure 1.6. Framework for Service Providers to Integrate Green Infrastructure 27
Figure 1.7. Map of Green Infrastructure Case Studies Featured in This Report 28
Figure 2.1. Mangrove Species Only Thrive in Specific Eco-regions 35
Figure 2.2. Varying Time Frames for Achieving Benefits with Green or Gray Components 37
Figure 2.3. Integrating Communities' Local Knowledge Enhances Modeling Tools for Green Infrastructure Planning 37
Figure 2.4. Restoring Meanders Alleviates Flooding by Giving Room to the River 41
Figure 2.5. New Technologies Can Support Green Infrastructure Planning and Monitoring 42
Figure 2.6. Flood Risk Monitoring 43
Figure 3.1. Communities Are at the Heart of Green Infrastucture Operations and Maintenance 48
Figure 3.2. Mapping Stakeholder Priorities, Natural Resource Restoration in Rwanda 51
Figure 4.1. Combining Green and Gray Infrastructure Can Be Cost-effective 58
Figure 4.2. Reducing Cost by Mixing Green and Gray Infrastructure, New York City 60
Figure 4.3. Cost-Effectiveness Analysis for Watershed Restoration Program, Brazil 61
Figure 4.4. Wetlands Conservation Cost-Benefit Analysis for Colombo, Sri Lanka 63
Figure 5.1. General Infrastructure Finance Model 66
Figure 5.2. Green Infrastructure Finance Model 67
Figure 5.3. Mangroves Stabilize Coastlines by Trapping Sediment in Their Roots and Reducing Wave Impacts with Their Dense Vegetation 68
Figure 5.4. Global Investments in Watershed Conservation, by Region 69
Figure 5.5. Integrating Nature into Infrastructure Designs Can Create Room for Rivers and Reduce Flood Risk 72
Figure 5.6. World Bank Green Infrastructure Projects, by Region 75
Figure 6.1. Agroforestry Can Boost Farm Productivity While Conserving Soil and Water 80
Figure 6.2. Green Roofs Help Control Urban Flooding While Also Reducing Heating and Cooling Needs for Buildings 83
Boxes
BOX 1.1. KEY TERMS 18
BOX 1.2. DEVELOPMENT PARTNER INITIATIVES TO SCALE GREEN INFRASTRUCTURE 21
BOX 1.3. SELECTED WORLD BANK NATURE-BASED SOLUTIONS REPORTS AND COMMUNITY OF PRACTICE 26
BOX 2.1. SUBSTITUTING GREEN FOR GRAY INFRASTRUCTURE: LESSONS FROM SOMALIA 34
BOX 2.2. ADVANCED MODELING AND MONITORING: THE NETHERLANDS SAND MOTOR 39
BOX 2.3. THE MANY USES OF GREEN INFRASTRUCTURE: LESSONS OF A CALIFORNIA FLOOD RETENTION PROJECT 40
BOX 2.4. USING REMOTE SENSING FOR GREEN INFRASTRUCTURE MONITORING: LESSONS FROM CHINA 43
BOX 3.1. COMMUNITY-LED RESTORATION DRIVES LONG-TERM SUCCESS: LESSONS FROM INDIA 47
BOX 3.2. INCENTIVIZING SHRIMP FARMERS TO MODIFY THEIR PRACTICES: LESSONS FROM VIETNAM 49
BOX 3.3. ADAPTING SOCIAL ANALYSIS FOR GREEN INFRASTRUCTURE: SELECT ASSESSMENT APPROACHES 50
BOX 3.4. APPLYING SOCIAL SAFEGUARDS TO GREEN INFRASTRUCTURE: LESSONS FROM POLAND 52
BOX 4.1. EXPANDED COST-EFFECTIVENESS ANALYSIS FOR WATERSHED RESTORATION PROGRAM IN BRAZIL 61
BOX 4.2. DECISION-MAKING UNDER UNCERTAINTY: LESSONS FROM SRI LANKA IN VALUING WETLANDS FOR URBAN FLOOD CONTROL 63
BOX 5.1. PUBLIC PROGRAMS AND BLENDED FINANCE PAY FOR GREEN INFRASTRUCTURE: LESSONS FROM BRAZIL 70
BOX 5.2. FINANCING URBAN GREEN INFRASTRUCTURE: LESSONS FROM THE UNITED STATES 71
BOX 5.3. WORLD BANK NATURE-BASED SOLUTIONS PROJECT PORTFOLIO, 2012-2017 74
BOX 6.1. CHANGING POLICY TO FACILITATE SERVICE PROVIDER INVESTMENT IN THE QUITO WATER FUND 78
BOX 6.2. POLICY INNOVATION SUPPORTS GREEN INFRASTRUCTURE IN COSTA RICA 81
Box Figures
Figure B5.3.1. World Bank Projects with Green Infrastructure Components 74
Table A1. Hectares Enrolled in the Payment for Ecosystem Services Program (by Activity) 93
Table A2. Contingent Payment at Mandatory Tender Date (April 1, 2021) 111
Table A3. Agricultural and Ancillary Benefits from Kumbharwadi Watershed Development Program 123
Figure A1. A Riparian Buffer Offers a Natural Filtration System That Helps Prevent Pollutants from Reaching the Water Stream 91
Figure A2. Coastal Mangroves that Help Stabilize Sediment and Attenuate Waves 97
Figure A3. Flooded Yolo Bypass, Diverting Waters from Inundating Low-lying Developed Areas and Relieving Pressure on Built Floodwater Management Infrastructure 103
Figure A4. Green Roof Atop a Parking Garage and Rail Yard in Illinois That Helps Slow Stormwater Runoff 109
Figure A5. Sand Dam in Somalia Used as Green Infrastructure for Aquifer Recharge 115
Figure A6. Ethiopia: Agroforestry on Steep Slopes Helps Prevent Soil Erosion and Improve Water Infiltration for More Productive Farming 121