Ganges Strategic Basin Assessment
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Public Disclosure Authorized Report No. 67668-SAS Report No. 67668-SAS Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized GANGES STRATEGIC BASIN ASSESSMENT: A Discussion of Regional Opportunities and Risks b Report No. 67668-SAS Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks World Bank South Asia Regional Report The World Bank Washington, DC iii GANGES STRATEGIC BASIN ASSESSMENT: A Discussion of Regional Opportunities and Risks Disclaimer: © 2014 The International Bank for Reconstruction and Development / The World Bank 1818 H Street NW Washington, DC 20433 Telephone: 202-473-1000 Internet: www.worldbank.org All rights reserved 1 2 3 4 14 13 12 11 This volume is a product of the staff of the International Bank for Reconstruction and Development / The World Bank. The findings, interpretations, and conclusions expressed in this volume do not necessarily reflect the views of the Executive Directors of The World Bank or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this work. The boundaries, colors, denominations, and other information shown on any map in this work do not imply any judgment on part of The World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Rights and Permissions The material in this publication is copyrighted. Copying and/or transmitting portions or all of this work without permission may be a violation of applicable law. The International Bank for Reconstruction and Development / The World Bank encourages dissemination of its work and will normally grant permission to reproduce portions of the work promptly. For permission to photocopy or reprint any part of this work, please send a request with complete information to the Copyright Clearance Center Inc., 222 Rosewood Drive, Danvers, MA 01923, USA; telephone: 978-750-8400; fax: 978-750-4470; Internet: www.copyright.com. All other queries on rights and licenses, including subsidiary rights, should be addressed to the Office of the Publisher, The World Bank, 1818 H Street NW, Washington, DC 20433, USA; fax: 202-522-2422; email: [email protected]. Cover photo: NASA; http://www.visibleearth.nasa.gov/ Cover design: Roots Advertising, Gurgaon, India iv Contents Acronyms xi Executive Summary xiii 1. Why Undertake A Strategic Basin Assessment? 1 2. Overview 3 The Ganges River Basin 3 The Water System 4 Water Management in the Basin 14 Socioeconomic Context 18 Institutions in the Basin 25 Climate Context 28 3. Analytical Framework 31 Overall Framework 31 Water Systems Modeling 32 Water Systems Modeling Scenarios 35 Water System Model Criteria and Indicators 35 Water Systems Model Calibration and Testing 36 Economic Optimization Modeling 42 Economics Optimization Model Data and Scenario Analysis 46 Social Analysis 47 4. Ten Fundamental Questions 49 Question 1 Is there Substantial Potential for Upstream Reservoir Storage in the Himalayan Headwaters of the Basin? 49 Question 2 Can Upstream Water Storage Control Basin Wide Flooding? 51 Question 3 Can Upstream Water Storage Augment Low Flows Downstream? 61 Question 4 Are there Good Alternatives or Complements to Reservoir Storage? 65 Question 5 Is there Substantial Untapped Hydropower Potential in the Ganges Basin? 69 Question 6 What is the Magnitude of Potential Economic Benefits from Multipurpose Water Infrastructure, and What are the Tradeoffs Among Different Water uses? 72 Question 7 What are the Cost- and Benefit-Sharing Dynamics of Upstream Water Storage Development? 79 Question 8 Is large Infrastructure the Best Strategy for Protecting Communities from Floods? 81 Question 9 Is it Possible to Control Sediment in the Ganges? 87 Question 10 What will Climate Change Mean for the Basin? 89 5. Findings, Implications, and Opportunities 101 Bibliography 106 v GANGES STRATEGIC BASIN ASSESSMENT: A Discussion of Regional Opportunities and Risks FIGURES Figure 1: Elevation Map of the Ganges Basin 3 Figure 17: Urban Population and Growth in the Ganges Basin 22 Figure 2: Schematic of the Major Tributary Contributions of the Ganges 4 Figure 18: Delhi City Expansion over 25 Years 23 Figure 3: Creation of the Himalaya 5 Figure 19: Land Use in the Ganges Basin 23 Figure 4: Map of South Asia with Separation Figure 20: Surface Water Quality in of the Ganges and Brahmaputra the Ganges Basin 24 Rivers 6 Figure 21: Climate Change Vulnerability Figure 5: Confinement of the South Asian Index, 2011 29 Monsoon 7 Figure 22: Climate Conflict Constellations 30 Figure 6: Path of the South Asia Monsoon 8 Figure 23: ‘Simplified’ Schematic of the Figure 7: Seasonal and inter-annual variability Ganges Basin Water Systems and of flow in the Ganges at Farakka. Economic Optimization Models 33 Data from Global Runoff Data Figure 24: Catchments in the MIKE BASIN Centre 1949-1973 8 Model and SWAT Model 34 Figure 8: Temperature and Precipitation in Figure 25: Water Quality Modeling in SWAT 34 the Ganges Basin 9 Figure 26: Flood Risk Management Figure 9: Drought and Flood Affected Analytical Framework 35 Populations in the Ganges Basin 11 Figure 27(a): Schematic Representation of Figure 10: Irrigation in the Ganges Basin 14 Storage Options 37 Figure 11: Irrigation Canals in the Figure 27(b): Schematic Representation of Ganges Basin 15 Storage Options 38 Figure 12: Major Dams and Barrages in the Figure 28: Major Impact Locations for Ganges Basin 16 the Water Systems Model 39 Figure 13: The Sites and Simulated Reservoirs Figure 29: Calibration and Validation of of the Three Largest Dams under the MIKE BASIN Model Consideration in Nepal 17 (Karnali Basin in Nepal) 41 Figure 14: GDP Per Capita, 2005 19 Figure 30: Calibration and Validation of Figure 15: Population Density in the the MIKE BASIN Model at Ganges Basin 20 Hardinge Bridge in Bangladesh 41 Figure 16a: Comparison of Population Living on Figure 31: Calibration of the MIKE 11 Less than $2 per day in the Ganges Hydrodynamic Model at Hardinge Basin and Sub-Saharan Africa 21 Bridge in Bangladesh 42 Figure 16b: Poverty rates and Population Figure 32: MIKE 21 Salinity Model: Density in the Ganges basin and Modeled River System of the Other Regions 21 South West 43 vi CONTENTS Figure 33: MIKE 21 Salinity Model: Figure 52: Monthly Generated Hydro power Comparison of Simulated and (Based on Model Results) 71 Measured Salinity in the Pussur River 44 Figure 53: Distribution of Economic Benefits Figure 34: Site Map of Focus Group Discussions 48 from All Proposed Large Dams 74 Figure 35: Current and Potential Surface Water Figure 54: Economic Benefits for Four Storage in the Ganges Basin 50 Assumptions of Irrigation and Figure 36: Gradients of Selected Himalayan Rivers 51 Low-Flow Values 76 Figure 37: Flooded Areas in the Ganges Basin 53 Figure 55: Tradeoffs between Water Uses 78 Figure 38: Flood-Related Deaths and Figure 56: Tradeoff between Irrigation Water Flood-Affected People in Bihar 55 Use and Low-Flow Augmentation 79 Figure 39: Flood Peaks on the Kosi River under Figure 57: Flood Typology of Southwestern Different Infrastructure Scenarios 56 Bangladesh 83 Figure 40: Flooded Areas and Kosi Basin Figure 58: Sedimentation in an Irrigation Boundaries 57 Canal in Uttar Pradesh 87 Figure 41: Embankments in the Ganges Basin 58 Figure 59: Schematic of Embankments in Figure 42: Timeline of Major Damage to Sediment-Laden Rivers 88 the Kosi Embankments 59 Figure 60: Sediment Flow in the Ganges- Figure 43: Flood Peaks at the India-Bangladesh Brahmaputra System 89 Border under Different Infrastructure Options 60 Figure 61: Temperature Predictions for Figure 44: Flood-Impacted Areas in the Ganges Basin for 16 GCMs 91 the Ganges Delta under Different Figure 62: Share of Glacier Melt in Nepal’s Infrastructure Options 61 Himalayan Rivers 92 Figure 45: Low Flows on the Kosi River under Figure 63: Rapidly Growing Glacier Lake 92 Different Infrastructure Options, 1998–2007 62 Figure 64: Water Balance and Snowmelt Contribution in Himalayan Basins 93 Figure 46: Low Flows on the Ganges at Hardinge Bridge 62 Figure 65: Predicted Sea-Level Rise and Figure 47: Ganges Water Quality in Critical Storm Surges in Bangladesh 94 Stretches 64 Figure 66: Erosion and Accretion along the Figure 48: Ganges Basin Groundwater Potential 66 Bangladesh Coast 95 Figure 49: Waterlogging Along the Sarda- Figure 67: Precipitation Projections for Sahayak Canal System in India 67 the Ganges Basin from 16 GCMs 96 Figure 50: High Groundwater Tables in Ghaghra- Figure 68: Runoff Predictions for Gomti Basin in Uttar Pradesh, India 68 the Ganges Basin from 16 GCMs 97 Figure 51: Hydropower Potential in Figure 69: Predicted (a) and Historical (b) Flow the Ganges Basin 71 Rates at Farakka on the Ganges 99 vii GANGES STRATEGIC BASIN ASSESSMENT: A Discussion of Regional Opportunities and Risks TABLES BOXES Table 1: Average Annual Suspended Sediment Box 1: Enduring Challenge of Floods Tackled Load 13 by Modern Technologies 13 Table 2: Population Profile of the Ganges River Box 2: Defining Floods and Droughts 29 Basin 18 Box 3: A Chronology of Recent Floods in Table 3: Population Density in the Ganges Bihar 54 Basin 21 Box 4: Are Embankments a Good Table 4: Water System Modeling Scenarios 36 Flood-Control Strategy? A Case Study of the Kosi River 86 Table 5: Key Criteria and Indicators for the Water Systems Models