Managing Coasts with Natural Solutions Guidelines for Measuring and Valuing the Coastal Protection Services of Mangroves and Coral Reefs WAVES TECHNICAL REPORT January 2016 Wealth Accounting and the Valuation of Ecosystem Services www.wavespartnership.org www.wavespartnership.org World Bank. 2016. Managing Coasts with Natural Solutions: Guidelines for Measuring and Valuing the Coastal Protection Services of Mangroves and Coral Reefs. M. W. Beck and G-M. Lange, editors. Wealth Accounting and the Valuation of Ecosystem Services Partnership (WAVES), World Bank, Washington, DC. www.wavespartnership.org Contents Acknowledgements --------------------------------------------------------------------------------------- 7 Abbreviations and Acronyms ---------------------------------------------------------------------------- 8 Executive Summary --------------------------------------------------------------------------------------- 9 1 Introduction ----------------------------------------------------------------------------------------- 21 1.1 Wealth Accounting and Valuation of Ecosystem Services (WAVES) -------------------21 1.2 Process for Developing the Guidance Note ------------------------------------------------ 22 1.3 How to Use the Information ------------------------------------------------------------------ 22 1.4 Limitations and Cautions --------------------------------------------------------------------- 23 2 Coastal Defense Services Provided by Mangroves -------------------------------------------24 2.1 Summary ----------------------------------------------------------------------------------------24 2.2 Introduction -------------------------------------------------------------------------------------24 2.3 Wind and Swell Waves ------------------------------------------------------------------------24 2.4 Storm Surges ----------------------------------------------------------------------------------- 32 2.5 Tsunamis ----------------------------------------------------------------------------------------39 2.6 Mangroves as a Form of Sustainable Coastal Defense -----------------------------------45 2.7 Conclusions ------------------------------------------------------------------------------------- 47 2.8 References -------------------------------------------------------------------------------------- 47 3 Coastal Defense Services Provided by Coral Reefs ------------------------------------------54 3.1 Summary ----------------------------------------------------------------------------------------54 3.2 Coral Reefs: Basic Ecology and Biogeography --------------------------------------------54 3.3 Role of Coral Reefs in Coastal Protection---------------------------------------------------55 3.4 Threats to Coral Reefs and Implications for Coastal Protection-------------------------59 3.5 Coral Reef Restoration ------------------------------------------------------------------------62 3.6 Engineered Structures ------------------------------------------------------------------------64 3.7 Cost Effectiveness of Coral Reef Restoration ----------------------------------------------67 3.8 Conclusions -------------------------------------------------------------------------------------67 3.9 References --------------------------------------------------------------------------------------67 4 Ecosystem Service and Coastal Engineering Tools for Coastal Protection and Risk Reduction---------------------------------------------------------------------------------75 4.1 Summary ---------------------------------------------------------------------------------------- 75 4.2 Introduction ------------------------------------------------------------------------------------- 75 4.3 Methods and results --------------------------------------------------------------------------- 76 3 Managing Coasts with Natural Solutions www.wavespartnership.org 4.4 General Ecosystem Service Tools—Measuring Multiple Ecosystem Services --------- 78 4.5 General Coastal Risk and Vulnerability Tools ---------------------------------------------- 81 4.6 Engineering Tools and Models: Process-based Approaches for Assessing Coastal Protection ---------------------------------------------------------------------------------------84 4.7 Summary and Advice ------------------------------------------------------------------------- 97 4.8 References -------------------------------------------------------------------------------------- 97 Appendix 4.1: A Summary and Comparison of Ecosystem Service Tools and Approaches ------------------------------------------------------------------------------105 Appendix 4.2: Brief Description of Coastal Engineering Model and Tools -----------------106 5 Approaches for Valuing Coastal Protection Services in a Natural Capital Accounting Framework--------------------------------------------------------------------------- 110 5.1 Summary --------------------------------------------------------------------------------------- 110 5.2 Introduction ------------------------------------------------------------------------------------- 111 5.3 Ecosystem Services Valuation ---------------------------------------------------------------112 5.4 Ecosystem Services and Natural Capital Accounting ------------------------------------119 5.5 The SEEA-Experimental Ecosystem Accounting -----------------------------------------121 5.6 Discussion -------------------------------------------------------------------------------------- 124 5.7 References ------------------------------------------------------------------------------------- 126 6 Coastal Protection Services from Coral Reefs and Mangroves in Policy and Practice: Case Studies ---------------------------------------------139 6.1 Summary --------------------------------------------------------------------------------------- 139 6.2 Introduction ------------------------------------------------------------------------------------ 139 6.3 Methods ----------------------------------------------------------------------------------------140 6.4 Results: The Influence of Protective Services on Coastal Policies and Practices ----140 6.5 Case Studies ------------------------------------------------------------------------------------141 6.6 Discussion -------------------------------------------------------------------------------------- 155 6.7 Conclusions ------------------------------------------------------------------------------------156 6.8 References ------------------------------------------------------------------------------------- 158 7 Recommendations --------------------------------------------------------------------------------163 7.1 The Evidence Base and Data Gaps ---------------------------------------------------------163 7.2 Models and Methods -------------------------------------------------------------------------164 7.3 Building Public and Governmental Support ----------------------------------------------165 7.4 Actions to Sustain and Enhance the Coastal Protection Value of Coral Reefs and Mangroves --------------------------------------------------------------------------------166 4 www.wavespartnership.org List of Figures Figure ES1: Conceptual Diagram of the Process-based Steps for the Assessment of Flooding and the Role of Habitats in Flood Reduction ---------------------------------15 Figure 2.1: Factors Affecting Wave Attenuation through Mangroves ---------------------------- 25 Figure 2.2: Variation in Wave Height with Distance Travelled through Mangrove Forests in Four Sample Locations in Vietnam (adapted from Bao 2011) ----------- 25 Figure 2.3: Wave Attenuation through Three Mangrove Species ---------------------------------29 Figure 2.4: Variation of the Drag Coefficient (here called the resistance coefficient) with the Projected Area of Obstacles (that is, mangrove vegetation) to Incoming Waves for Kandelia candel in the Red River Delta, Vietnam (data from Quartel et al. 2007) -----------------------------------------------------------30 Figure 2.5: Variation of Wave Attenuation with Significant Wave Height (the mean height of the highest third of the waves) in Areas with and without Mangroves (Sonneratia spp. in Vietnam, data from Mazda et al. 2006) --------------------------30 Figure 2.6: Demonstration of How Mangrove Coastal Defense Services can be Calculated using Appropriate Numerical Models -------------------------------------- 32 Figure 2.7: Reduction of Storm Surge Height by Mangroves on the Gulf Coast of South Florida, United States during Hurricane Wilma (2005, Category 3 on impact), Modeled using CEST (data from Zhang et al. 2012) ---------------------36 Figure 2.8: Diagram Showing how Mangrove Soil Surfaces can Rise with Sea-level Rise, Potentially Allowing Mangroves to Keep Pace with Sea-level Rise ------------------45 Figure 2.9: Graph Showing that Mangroves in Belize Have Accumulated Peat at a Rate Consistent with Sea-level Rise in the Caribbean area (data from Toscano and Macintyre 2003 [sea-level curve] and McKee et al. 2007 [mangrove peat data]) ---------------------------------------------------------------------46 Figure 3.1: Coral Reef Types and Morphology related to Exposure and Platform Slope and Width -----------------------------------------------------------------56 Figure 3.2: Wave Energy Reduction by Coral Reefs (adapted from Ferrario et al. 2014) ------------------------------------------------------------------------- 57 Figure 3.3: Full Cycle of Development of Fringing Reef Crest in a High Energy, Windward Setting --------------------------------------------------------------------------58