Extending the Life of ReservoirsExtending the Life Public Disclosure Authorized Public Disclosure Authorized DIRECTIONS IN DEVELOPMENT Energy and Mining Annandale, Morris, and KarkiAnnandale, Extending the Life of Reservoirs Public Disclosure Authorized Sustainable Sediment Management for Dams and Run-of-River Hydropower George W. Annandale, Gregory L. Morris, and Pravin Karki Public Disclosure Authorized Extending the Life of Reservoirs DIRECTIONS IN DEVELOPMENT Energy and Mining Extending the Life of Reservoirs Sustainable Sediment Management for Dams and Run-of-River Hydropower George W. Annandale, Gregory L. Morris, and Pravin Karki © 2016 International Bank for Reconstruction and Development / The World Bank 1818 H Street NW, Washington, DC 20433 Telephone: 202-473-1000; Internet: www.worldbank.org Some rights reserved 1 2 3 4 19 18 17 16 This work is a product of the staff of The World Bank with external contributions. 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Library of Congress Cataloging-in-Publication Data has been requested Extending the Life of Reservoirs • http://dx.doi.org/10.1596/978-1-4648-0838-8 Contents Foreword xiii About the Authors xv Abbreviations xvii Chapter 1 Purpose and Application of This Book 1 Pravin Karki Introduction 1 The World Bank’s Role in Sustainable Infrastructure Activities 2 The Importance of Sediment Management for Ensuring the Sustainability of Reservoir and Run-of-River Projects 2 Solutions and Recommendations for Successful Sediment Management 3 Purpose, Uses, and Organization of This Book 4 Notes 5 References 5 Chapter 2 Climate Change, Sediment Management, and Sustainable Development 7 George W. Annandale Introduction 7 The Dual Nature of Reservoir Storage 9 Shifting Paradigms 10 Economic Analysis and Sustainable Development 15 Summary 20 Notes 20 References 20 Chapter 3 Overview of Sedimentation Issues 23 George W. Annandale Introduction 23 The Importance of Storage 23 Extending the Life of Reservoirs • http://dx.doi.org/10.1596/978-1-4648-0838-8 v vi Contents Sedimentation Impacts Upstream of a Dam 26 Sedimentation Impacts Downstream of a Dam 34 Importance of Sediment Management 36 Severity of Storage Loss to Sedimentation 40 Sedimentation and Climate Change 41 Notes 42 References 43 Chapter 4 Sediment Yield 45 George W. Annandale Introduction 45 Global Sediment Yield: Spatial Variability 45 Sediment Sources 48 Measuring Sediment Yield 53 Sediment Yield Estimation 56 Note 58 References 58 Chapter 5 Patterns of Sediment Transport and Deposition 61 George W. Annandale Introduction 61 Sediment Transport in Reservoirs 61 Trap Efficiency 62 Spatial Distribution of Deposited Sediment 63 Empirical Techniques 67 Computer Simulation 73 Particle Size Distributions of Deposited Sediment 73 Temporal Aspects of Sediment Deposition 74 Note 75 References 75 Chapter 6 Sediment Monitoring 77 Gregory L. Morris Introduction 77 Sampling for Suspended Sediment Load 78 Sediment Rating Curves 82 Bed Material Load 88 Bathymetric Mapping of Sedimentation 89 Sediment Bulk Density 93 Sediment Sampling of Grain Size Distribution 95 Summary 97 References 97 Extending the Life of Reservoirs • http://dx.doi.org/10.1596/978-1-4648-0838-8 Contents vii Chapter 7 Sediment Management Techniques 99 Gregory L. Morris Introduction 99 Reducing Upstream Sediment Yield 99 Sediment Routing 105 Redistributing or Removing Sediment Deposits 112 Management Options and Reservoir Capacity 118 Adaptive Strategies 120 Sediment Modeling Approaches 121 References 125 Chapter 8 Sediment Management at Run-of-River Headworks 127 Gregory L. Morris Introduction 127 Configurations of ROR Hydropower Plants and Objectives of Headworks Design 128 Fluvial Morphology and Site Selection 130 Types of Intakes 133 Sediment Management at Headworks 135 Removal of Sand from Diverted Water 138 Monitoring and Sediment-Guided Operation 143 Notes 147 References 147 Chapter 9 Reservoir Sustainability Best Practices Guidance 149 Gregory L. Morris Introduction 149 Sustainable Reservoirs and Hydropower 150 Limitations of Sediment Management 153 Planning and Design Considerations 155 Monitoring Sediment Management Performance 159 End-of-Life Scenarios 160 Note 161 References 161 Appendix A Checklist for Sediment Management 163 Sediment Yield 163 Sedimentation Patterns and Impacts 165 Sustainable Sediment Management Measures 167 Development Paradigm 168 Extending the Life of Reservoirs • http://dx.doi.org/10.1596/978-1-4648-0838-8 viii Contents Boxes 2.1 Sediment Management in the Dasu Hydropower Project, Pakistan 10 2.2 A Note on Terminology 13 2.3 Tarbela Dam, Pakistan 16 Figures 2.1 Active Storage Features of Run-of-River and Storage Reservoirs 8 2.2 Design Life Approach to Infrastructure Design 12 2.3 The Life-Cycle Management Approach 14 2.4 Standard Approach to Economic Analysis of Dams and Reservoirs, PD Soedirman Reservoir, Indonesia 15 2.5 Life-Cycle Approach Reflecting Sediment Management Investments 19 3.1 Relationship between Yield and Hydrologic Variability at 99 Percent Reliability 25 3.2 Storage Loss in Active and Dead Storage Zones Due to Reservoir Sedimentation 26 3.3 Changes in Water Use Efficiency Relative to Sedimentation in the Active Storage of a Reservoir over Four Decades 28 3.4 Changes in Water Use Efficiency Relative to Sedimentation in the Active Storages of Reservoirs 28 3.5 Relationship between Dimensionless Yield and Dimensionless Reservoir Storage for Varying Hydrologic Variability 31 3.6 Positive Effect on Water Supply of Reservoir Sediment Management 32 3.7 Increased Flood Elevations Caused by Sediment Deposition 33 3.8 Erosion and Degradation of Downstream Rivers Due to “Sediment Hungry” Water 34 3.9 Relationship between Annual Average Flood Control Benefit and Flood Control Storage for Three Gorges Dam, China 36 3.10 Cumulative Yield as a Function of Unit Cost for All Potential Dam and Reservoir Sites in Kenya 37 3.11 Adverse Effect of Developing Dams and Their Reservoirs in a Nonsustainable Manner 38 3.12 Long-Term Reduction in Reservoir Storage Space from Reservoir Sedimentation 39 3.13 The Effect of Successful Reservoir Sediment Management 40 3.14 Global Population Growth and Reservoir Storage Volume 41 3.15 Net Global Reservoir Storage Volume, Accounting for Storage Loss from Reservoir Sedimentation 42 4.1 Specific Sediment Yield as a Function of Effective Precipitation and Terrain and as a Function of Mean Annual Precipitation and Geology 49 Extending the Life of Reservoirs