Report No. 67668-SAS 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 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: pubrights@worldbank.org. 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 Comparison of Population Living on Figure 16a: 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 Poverty rates and Population Figure 16b: 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 40 Table 6: Assumptions of Irrigation and Low-Flow Values in the Economic Optimization Model 47 Table 7: Existing and Proposed Dams in the Ganges Basin over 100m High, with Global Comparators 52 Table 8: Low Flow Augmentation in Irrigation, as Allocated by the Economic Optimization Model 63 Table 9: Range of Economic Optimization Model Outcomes for Different Infrastructure Options 73 Table 10: Percent Reductions in Peak Flow in the Ganges Main Stem and Major Tributaries 74 Table 11: Irrigation and Low-Flow Outcomes for Different Water Assumptions with Full Infrastructure Development 75 Table 12: Benefit Assumptions for Himalayan Dams 79 Table 13: Decadal Population Growth Rate Estimates 84 viii Acknowledgments The Ganges Strategic Basin Assessment is a product Himalayas. Michael Westphal analyzed historical of an extensive collaborative effort among many climate and climate change scenarios for the basin. professionals within and outside the World Bank. It is The Center for Environmental and Geographic an output of the South Asia Water Initiative (SAWI), Information Services (CEGIS) in Dhaka, the which is a partnership of the World Bank and the International Centre for Integrated Mountain governments of the United Kingdom, Australia and Development (ICIMOD) in Kathmandu, and Norway, that seeks to facilitate regional cooperation the International Water Resources Management in the sustainable use and management of the water Institute (IWMI) in India and Nepal provided the resources of the Himalayan Rivers. team a wealth of pertinent information. Mary Paden provided editorial support. The work was led by Claudia Sadoff and Nagaraja Rao Harshadeep of the World Bank. The core team Important contributions were made by Stephanie included Donald Blackmore, Marc Jeuland, Sylvia Borsboom, Biva Chapagain, Genevieve Connors, Lee, Anna O’Donnell, Dale Whittington, Wu Xun, Charles Cormier, Ajaya Dixit, Daryl Fields, Dipak Jorge Escurra, Hrishikesh Patel and Lauriane Cayet. Gyawali, Ejaz Ghani, Drona Ghimire, Natalie The report could not have been produced without Giannelli, Sanjay Gupta, Michael Haney, Christine the administrative support of Sulochana Nepali, Kimes, Khawaja Minnatullah, Siet Meijer, Pratibha Rachel Susan Palmer, Pamela Patrick, and Tara Mistry, Ainun Nishat, Hubert Nove-Josserand, Shrestha. Specific inputs to this study were provided Sanjay Pahuja, R.S. Pathak, Anil Pokhrel, Giovanna by a broad range of experts and institutions. In Prennushi, Martin Rama, Shyam Ranjitkar, Catherine particular, the Institute for Water Management Revels, Bharat Sharma, Mandira Shrestha, Animesh (IWM) in Dhaka developed the calibrated Ganges Shrivastava, Ranu Sinha, Ashok Subramanian, Basin model and worked closely with the World Catherine Tovey, Rajib Upadhya, George Verghese, Bank team in analyzing the implications of major Winston Yu and William Young. Individuals too future scenarios. IWM’s work was led by Bushra numerous to name provided extremely useful Nishat and Asif Zaman with guidance from insights at consultation meetings held with a variety Mahbub-ur-Rahman and Emaduddin Ahmed. INRM of government and donor partner agencies, and Ltd. (Integrated Natural Resource Management research, policy, and academic institutions in Consultants) in Delhi developed the calibrated Bangladesh, India and Nepal. SWAT model for the Ganges Basin under the leadership of Ashwin Gosain (Indian Institute of The team benefitted from the advice of a broad Technology, Delhi), R. Srinivasan (Texas A&M range of colleagues. It wishes to express its University) and Sandhya Rao. RMSI Pvt. Ltd., Delhi, appreciation for the guidance and support of supported work on flood and drought analysis. colleagues within the World Bank including Kalpana E. Somanathan, of the Indian Statistical Institute, Kochhar, Roberto Zagha, Susan Goldmark, Ellen undertook an investigation of the economics of Goldstein, Jack Stein, Salman Zaheer, Rachid ‘hard’ versus ‘soft’ flood mitigation strategies. Don Benmessaoud, Gajanand Pathmanathan, Herbert Alford, Richard Armstrong, and Adina Racoviteanu Acquay, Karin Kemper, and Julia Bucknall. A special estimated glacier melt contributions from the Nepal thanks to Ngozi Okonjo-Iweala and Isabel Guerrero ix Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks for their guidance in key consultations. The team Semund Haukland, Guy Howard, Russell Rollason is also grateful to have received input from two and Clare Shakya, also provided insightful and advisory groups outside the Bank: an international substantive support to the team. Expert Advisory Group, comprising David Grey, Glenn Jenkins, Mark New, and Peter Rogers; and The team gratefully acknowledges support the Abu Dhabi Dialogue Group of regional experts. from the SAWI and the World Bank South Asia The SAWI development partners (the Governments Regional Integration Unit, and sincerely thanks all of Australia, Norway and the United Kingdom), in of the individuals and institutions met during the particular Bente Binge, Simon Buckley, John Dore, development of this work. x Acronyms ABC Asia brown cloud ADPC Asian Disaster Prevention Center BADC British Atmospheric Data Centre BBS Bangladesh Bureau of Statistics BCM billion cubic meters ENSO El Ñino Southern Oscillation FMIS Flood management information system GCM Global Circulation Models or General Climate Model GDP Gross Domestic Product GIS Geographic Information System GLOF Glacier Lake Outburst Flood GRDC Global Runoff Data Center ICIMOD International Centre for Integrated Mountain Development IPCC Intergovernmental Panel on Climate Change IWM Institute for Water Modeling JRC Joint Rivers Commission JCWR Joint Committee on Water Resources KWh Kilowatt hour MW Megawatt NCAR National Center for Atmospheric Research NGRBA National Ganga River Basin Authority OCHA Organization for the Coordination of Humanitarian Assistance SAARC South Asian Association for Regional Cooperation SAWI South Asia Water Initiative SBA Strategic Basin Assessment SRTM Shuttle Radar Topography Mission SMEC Snowy Mountain Engineering Corporation SWAT Soil and Water Assessment Tool TWH Terawatt Hour UNDRO UN Disaster Relief Organization UNFCCC United Nations Framework Convention on Climate Change UP Uttar Pradesh USGS United State Geological Survey xi Executive Summary The Ganges river basin is the most populous in the lead to greater cooperation in the management of world. The daily lives of its 655 million inhabitants this shared river system, beginning with a shift from rely on the water it provides. The river presents information secrecy to information sharing. The key great opportunities and great challenges. It provides feature of this regional research is the development drinking water, agricultural water, hydropower of a set of nested hydrological and economic basin generation, and navigational and ecosystem services models, along with targeted analyses on social across more than 1 million square kilometers. But vulnerability and climate change. The mosaic the river is destructive as well; devastating of information produced using these tools and floods and periodic droughts are routine and approaches can be used to examine alternative undermine development. scenarios across a range of possible Ganges futures. All countries in the basin benefit from the Ganges Until now, there has been no basinwide knowledge and suffer from its extremes; all could benefit more base and analytical framework that could be used and suffer less. Benefits from potential hydropower by riparian states to explore options and facilitate development and agricultural modernization remain cooperative planning in the Ganges. Information untapped, while flood and drought management and data are surprisingly scarce and difficult systems are inadequate to protect lives and to obtain. In particular, very little information is livelihoods. Better management of the Ganges – to available on hydrology and irrigation withdrawals in sustain the river ecosystem, capture its potential India. Significant efforts were made to assemble the benefits, and mitigate its mounting costs – requires data sets used in this analysis, drawing on publicly enhanced regional knowledge and cooperation. available data in Bangladesh, India, and Nepal, and on global data sets. The effort was undertaken Currently, most development in the basin is through by a World Bank team in cooperation with several incremental, project-by-project activities within each leading regional research institutions and involved of the riparian countries. There has been surprisingly repeated exchanges with policy makers and opinion little systematic regional research on the basin’s makers in the basin. development options and challenges using modern analytical tools that go beyond sector, country, or The Ganges SBA begins to fill a crucial knowledge state analysis to examine the systemwide strategic gap, providing an initial integrated systems questions that the basin faces. In addition, long- perspective on the major water resources planning held perceptions of the current condition and the issues facing the basin today, and on some of the future development path of the Ganges Basin vary most important infrastructure options that have dramatically within and among different stakeholder been proposed for future development. A set of groups, institutions, and countries. reliable hydrological and economic models for the Ganges system has been developed and tested. The objective of the Ganges Strategic Basin These models are believed adequate for assessing Assessment (Ganges SBA) is to build knowledge the impact of existing and new hydraulic structures and promote an open, evidence-based dialogue on on flooding, hydropower, low flows, water quality, the shared opportunities and risks of cooperative and irrigation supplies at the basin scale. It is management in the basin. It is hoped that this will important to emphasize that this report focuses only xiii Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks on basin-level dynamics; any specific projects under harnessed through large multipurpose dams to consideration would still require full economic, produce hydropower, deliver more timely irrigation environmental, and social assessments with specific water, and regulate the extreme flows of the attention to local ecological, seismic, and cultural Ganges River. contexts. Although the work has been constrained by important data limitations, and significant climate Although there are many reservoir sites that are change uncertainties persist, the basic conclusions of attractive for the development of multipurpose these assessments are robust and have been used to water storage infrastructure, the steep terrain develop some strategic insights. and mountain gorges mean that surprisingly little water can be stored behind even very high dams. The new information contained in this report Developing all of the structures examined in this challenges many long-held beliefs about the Ganges report would provide additional active storage River Basin. The system is so large (over 1 million equivalent to only about 18 percent of the basin’s square kilometers) and so complex (with thousands annual average flow. This is very little storage on a of tributaries fed by glacier and snow melt, monsoon basinwide scale. Moreover, the extent to which dams rains, and groundwater base flows) that it simply in Nepal can be operated to efficiently pass the cannot be understood intuitively. As a consequence, it large amounts of sediment eroded from high in the appears that some of what has long been considered Himalaya remains unclear. ‘common knowledge’ is, in fact, inaccurate. Question 2: In particular, the findings of this study refute the Can upstream water storage control broadly held view that upstream water storage (i.e., basinwide flooding? reservoirs) in Nepal can control basinwide flooding; however, at the same time it finds that such dams Large Himalayan dams are commonly seen as the could potentially double low flows in the dry months. answer to the flooding that plagues the Ganges The value of doing so, however, is surprisingly plains and delta, especially in areas of Bangladesh, unclear and similar storage volumes could be Bihar, and eastern Uttar Pradesh. Model results and attained through better groundwater management. research reveal a different picture. Hydropower development and trade are confirmed to hold real promise (subject to rigorous project On a basinwide scale, the potential to control level assessment with particular attention to sediment floods using upstream storage is very limited. and seismic risks), and in the near to medium term The full active storage potential that has been pose less significant trade-offs than expected among identified to date in the system (existing storage different water uses. plus the additional 18 percent examined in this report) amounts to approximately 25–30 percent The Ganges SBA study focused on ten fundamental of average annual river flows. This is simply too questions. small a percentage to meaningfully regulate the full river system. This limited scale of potential Question 1: storage severely constrains riparians’ ability to ever Is there substantial potential for upstream truly regulate this river system, even assuming an reservoir storage in the Himalayan aggressive development of system storage. On headwaters of the basin? the positive side, the lack of substantial regulation will preserve a more natural hydrology in the river Much has been written about the potential for system, which provides a wide variety of services large water storage structures in the Himalaya. It that have not been quantified in this report, such as is generally assumed that this potential could be ecosystem services and navigation. xiv Executive Summary The Ganges SBA models indicate that even the very minor portion of the flood flows until the dry season large proposed Kosi High Dam could not completely could significantly increase low flows especially in control flood peaks because the dam, which would a very dry years. Low-flow augmentation may be provide only 9.5 billion cubic meters of live storage, large relative to current low flow, but it is negligible would be built on a river with an average annual compared to peak flow, so the integrity of the flow of 55 billion cubic meters (much higher in hydrological system as it currently stands is unlikely many years). Moreover, the important question to be threatened by infrastructure development. is not whether the Kosi High Dam could reduce flood peaks; but whether reducing flood peaks in However, the economic value of this low-flow the Kosi River would stop flooding in Nepal and augmentation is unclear because of low agricultural Bihar. Unfortunately, the evidence suggests that the productivity and localized waterlogging. Water is dam’s impact on flooding would likely be modest not seen to be the crucial constraint to agricultural because most of the flooding in Nepal and Bihar productivity in the specific parts of the Ganges lies outside the Kosi subbasin. The majority of floods Basin that could receive these additional low flows. are a consequence of intense local rainfall and/or Even if these dams were built (at high costs and high flows in other river systems that would not be likely over decades) agricultural modernization is affected by building the Kosi High Dam. required to increase productivity. This modernization would be beneficial regardless of upstream dam In fact, the Ganges SBA models showed that construction. The effects of increased low flows may most flooding events in the basin are caused by make important contributions in the Ganges delta localized rainfall, high flows in small tributaries, areas to better manage saline intrusion, enhance and embankment failures – not by peak flows the Sundarbans ecosystem, and maintain navigation overtopping embankments in the major tributaries services. These are important issues that require where large storage reservoirs could be built. Even additional research. though a moderate amount of flow could be stored in reservoirs on major tributaries, almost all of the major Question 4: tributaries in the basin are fully embanked. Lowering Are there good alternatives or complements to flood peaks within these embanked rivers is unlikely to reservoir storage in the Himalaya? have a significant effect on flooding events. Many believe that large human-created infrastructure Question 3: (dams) is the only option of adequate scale to Can upstream water storage augment low meet the basin’s needs, given the region’s growing flows downstream? populations and economies. Although underground aquifers, lakes, glaciers, snow, ice, and even soils In addition to holding back floods, Himalayan are all forms of natural water storage, it is widely reservoirs are expected to release water stored during believed that they are relatively small, that the basin’s the wet season for use in the dry season. These groundwater is being drastically overexploited, and releases could augment low flows for ecosystems, that its glaciers are melting rapidly. agriculture and other uses across the basin especially in the dry months preceding the monsoon. In fact, contrary to the increasingly dangerous levels of groundwater overabstraction elsewhere in In physical terms, the modeling results confirm this South Asia, there are vast, untapped groundwater expectation. Low-flow augmentation could indeed be resources in the central and lower reaches of the significant if all the large dams under consideration Ganges Basin. These additional groundwater were built, approximately doubling low flows in resources, held in natural underground aquifers, the months with the lowest flows. Storing even a can be sustainably used. Increased strategic and xv Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks sustainable use of this groundwater, in conjunction source of clean energy in a region that is enjoying with a well-managed surface water system, could high economic growth and hence rapidly growing provide water supply benefits on a scale comparable power demands. to the full suite of dams considered in this report; and it could possibly do so more immediately, at Question 6: national, state or local levels, and at lower financial, What is the magnitude of potential economic social, and environmental costs. Moreover a benefits from multipurpose water infrastructure, conjunctive-use strategy could be designed to help and what are the tradeoffs among different manage soil waterlogging and enhance the reliability water uses? of water supplies to tail-end users in surface irrigation schemes and/or downstream irrigators There is a general sense in the region that the in the eastern basin. Achieving all of this, however, development of multipurpose infrastructure will would require significant reforms particularly in the bring significant economic benefits, but there policy and energy-pricing environment, and real is no shared understanding about the relative changes in farmers’ behavior. values of hydropower, flood control, and low-flow augmentation. It is also widely believed that the Question 5: design and operation of multipurpose dams will Is there substantial untapped hydropower significantly skew the distribution of benefits among potential in the Ganges Basin? water uses (and hence users). The tradeoffs are believed to be very large, and therefore are a matter The Himalaya has long been seen as holding of concern and contention particularly in negotiations enormous hydropower potential, adequate to meet between India and Nepal on the development and domestic energy needs in Nepal (where potential financing of large multipurpose water infrastructure. supplies far outstrip potential demand) and provide a significant surplus for trade in the region. This report finds that the gross economic benefits of hydropower from the 23 large dams examined under This report confirms that potential. In Nepal more different scenarios of infrastructure development than 40,000 megawatts of economically feasible would be in the range of US$3–8 billion per year hydropower potential exists in the Himalayan (assuming that 25 percent of it could be sold as headwaters of the Ganges. Less than 2 percent higher-value peaking power.) For the most part, the of that potential has been developed. The suite of economic tradeoffs among hydropower, irrigation, dams examined in this report, the 23 largest of them flood control, and ecological objectives are small, currently under consideration in Nepal, would have because there is little difference in the way upstream an installed capacity of about 25,000 megawatts, dams would be operated to maximize hydropower generating an estimated 65-70 terrawatt hours of generation on the one hand, and downstream water power annually. The net economic value of this supply on the other (since the objective for both of potential hydropower is estimated at some US$5 these is to store peak flows to achieve steadier dry- billion annually, quite significant relative to Nepal’s season releases); and because options to control 2011 gross domestic product (GDP) of $18.9 billion downstream flooding are limited regardless of how (current US $). It must be noted, however, that operating rules are designed. There is a tradeoff hydropower development on this scale would require in the quantity of water used for irrigation in the considerable capital investment and take many Ganges plains versus low-flow augmentation in years, and that sediments will need to be effectively the delta, but there is currently insufficient evidence managed. Nonetheless, hydropower is an important to determine whether this tradeoff is economically xvi Executive Summary significant: the evidence suggests that the marginal Question 8. economic benefit associated with surface water Is large infrastructure the best strategy for irrigation in the plains is currently quite low and the protecting communities from floods? economic value of increased low flows for ecosystem services is uncertain. Infrastructure is often seen as the most effective and reliable way to protect communities from endemic Question 7. flooding in the Ganges plains. The findings of this What are the cost- and benefit-sharing dynamics report, however, show that a strategy exclusively of upstream water storage development? focused on large infrastructure cannot protect basin communities. Perceptions differ by country, but it is generally perceived that downstream countries will benefit greatly from upstream development and therefore There is no simple solution to the problem of should share the costs of that development. Some flooding on the Ganges plains. In some areas of believe that the majority of benefits from upstream the world, a focus on large infrastructure (dams and water storage will not accrue from hydropower embankments) has been fairly effective. However, in development upstream, but rather from flood control the highly variable monsoon-driven Ganges system and irrigation benefits downstream. A common with its thousands of tributaries, these solutions will understanding of the distribution of benefits is not be fully effective. To protect communities in the essential to negotiating equitable benefit-sharing Ganges Basin, a shift in focus is needed from ‘flood arrangements on infrastructure developments that control’ to ‘flood management,’ a combination of have cross-border impacts. structural and nonstructural interventions marked by a greater emphasis on regional forecasting and If upstream multipurpose dams were built today, warning systems, embankment asset management, with current low agricultural productivity and little drainage, and, importantly, more localized ‘soft’ flood benefit, this study finds that the overwhelming responses including disaster preparedness, land share of economic benefits would be derived from use zoning, safe havens, flood insurance, and hydropower. In the future, if agricultural productivity training and communications campaigns. Indeed, rises dramatically, the distribution of benefits could in recent years, this shift has been the subject of a change. The principal unknowns in this equation are great deal of thoughtful advocacy. Flood protection the ecosystem and navigation values of enhanced low flows in the delta, which could be significant. for basin communities and the livelihoods of their The study’s findings suggest, however, that the people requires a broad, balanced combination of benefit-sharing calculus is simpler than previously ‘hard’ and ‘soft,’ as well as local and transboundary, assumed because downstream flood control and responses. agricultural benefits are smaller than anticipated – at least in the near to medium term. The benefits Question 9. and costs to be shared in the near term will be Is it possible to control sediment in the Ganges? predominantly associated with hydropower. In the long term, if the value of low flows to agriculture Many believe that in the Ganges, like elsewhere in and ecosystems increase, the benefit-sharing the world, a combination of watershed management calculus becomes more complex because the to control erosion and upstream storage structures benefits received by India and Bangladesh could might control sedimentation in the river. But the become significant. Ganges is different. xvii Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks The Ganges is one of the three most sediment-laden scale and focus of today’s climate challenges – rivers in the world. Most of the sediment comes from unpredictable and intense rainfall, alternating erosion in the high Himalaya. Both the high volume extremes of flood and drought – will continue to be and the source of this sediment make it extremely the key climate challenges in the coming decades. difficult to manage. The volume of sediment is so A focus on managing current hydrological variability large that capturing it behind large dams would be (whether or not it is attributable to climate change) extremely costly; the reservoirs behind these large, is, therefore, a good place to start addressing the expensive structures would fill quickly and, thereafter, future climate change challenges of the Ganges. produce very few benefits. The high altitude and terrain of the sediment source regions, as well as Even the most extreme climate scenarios do not the nature of the sediment and the ongoing tectonic change the basic findings of this report. In fact, processes, make it impossible to undertake the scale greater climate extremes, variability, and uncertainty of watershed management interventions necessary only strengthen the logic of this report’s basic to have any measurable impact on basin sediment recommendations, whereas the effectiveness of loads. Sediment, like floods, is a challenge that must large-scale infrastructure for flood control, and be managed in the Ganges; it cannot be the reliability of existing large-scale diversions of fully controlled. surface water for irrigation, could prove susceptible Question 10. to climate change. The recommendations of this What will climate change mean for the basin? study are likely to become more valuable under greater climate extremes. Regardless of changes in Many fear that the Himalayan glaciers will melt rainfall and hydrology, an emphasis on enhanced and change the Ganges River from a perennial forecasting and warning systems, in concert with to a seasonally flowing river, and that changing a suite of tailored, localized responses, is urgently temperatures and precipitation patterns will create needed. Similarly, the need and potential for crippling water stress as well as more severe and enhanced conjunctive use of surface water and more frequent droughts and floods. groundwater only becomes more compelling as temperatures, and hence evaporation rates of This study found that climate change uncertainties in surface storage, increase, and the timing of surface South Asia and the Ganges Basin in particular are flows becomes less predictable. extreme, but that the range of mean basin runoff predictions is roughly comparable to the recent historical record and the basin’s highly variable With regard to the glaciers, the study found that climate today. while the rate of glacier melt is likely to increase somewhat, glacier melt contributes only about 2 The study estimated temperature, rainfall and percent of basinwide flow. In addition, melting runoff for the Ganges Basin using all 16 United occurs mostly during the high-flow season in the Nations Framework Convention on Climate Change Ganges. In contrast to Europe and North America, (UNFCC)-recognized Global Circulation Models or even in the western Himalaya, where glacier melt (GCMs). Although there appears to be a clear trend contributes substantially to low summer flows, the toward rising temperatures, predictions regarding Himalayan glaciers in the Ganges Basin melt during rainfall and runoff vary widely and point to the the monsoon season when temperatures are highest possibility of either increasing or decreasing water but rainfall is also heaviest. Thus, while changes in availability. The range of model results underscore glacier melt will be an existential challenge for some their uncertainty, and their predictions can mask melt-dependent mountain communities, it is not a extremes, but these results do suggest that the major driver of basinwide hydrology in the Ganges. xviii Executive Summary Summary Findings sharing protocol; to a dedicated task for or agency that would gather, analyze, and then disseminate The Ganges SBA highlights the uniqueness and the complexity of the Ganges Basin, and demonstrates crucial hydromet and climate data; to an inclusive the urgent need for a shared evidence-based river commission that could develop a shared understanding of the full basin system. It calls for knowledge base and operational model of the basin, significantly enhanced regional cooperation in establish norms and protocols for transparency water, weather, and climate information, modeling and information sharing, and identify and pursue and warning systems which are essential for the opportunities for cooperative development projects. sustainable management of the basin and the safety A strengthened regional information system would and prosperity of its people. The report’s sometimes provide the scientific information needed by planners counter-intuitive findings highlight the need to revisit to sustain and develop the basin; by farmers to commonly held perceptions using modern data enhance productivity and food security; by disaster sources and modeling techniques to come to fact- risk management professionals to safeguard based understandings about the basin’s resources lives and assets; and by climate researchers to and possible future development paths. understand, predict, and adapt to the changing – but also immediately challenging – climate in the The Ganges Basin holds clear and immediate Ganges Basin. opportunities for regional cooperation in information management to enhance the productivity and Immediate opportunities are also apparent for sustainability of the river, and at the same time hydropower development and trade. There is safeguard lives and livelihoods. Systematic significant untapped potential in the basin and a collection and exchange of appropriate, modern steadily growing demand for clean energy. Moreover water, weather, and climate data; cooperative the benefit-sharing calculus appears simpler than efforts in advanced modeling, forecasting, and commonly believed, for several reasons. First, the communications and warning systems; and a tradeoffs among different water uses are modest. shared information base for basin planning will help Infrastructure would be designed and operated much the countries seize the basin’s opportunities and the same way whether the goal was to maximize manage its risks. The pieces are all in place. There hydropower, or to maximize flood and irrigation is tremendous expertise in the region. Bangladesh benefits downstream. In addition, the small storage boasts world-class water modeling institutions and compared to the river flows should make the pace cutting edge flood warning systems. India’s long of filling reservoirs not a major issue. Negotiations experience in water engineering is now coupled with over the design and operation of multipurpose burgeoning satellite and information technologies infrastructure with transboundary impacts should sectors, essential for modern hydrometeorology. therefore be tractable. Second, the current economic Nepal, with its wealth of water resources, sets value of downstream irrigation is surprisingly small an excellent global example for information compared with hydropower benefits, due to low sharing by making real time hydrological data agricultural productivity. At least in the near term, available online. Moreover, all three countries are the direct economic benefits of upstream reservoirs involved in or planning significant investments in would derive overwhelmingly from hydropower. hydromet monitoring systems, systems that could Co-benefits for agriculture should be amenable to be made interoperable for basinwide information transparent negotiations. Third, flood benefits (if management. any) are confined to tributaries. Upstream storage will have negligible basinwide flood impact. Cooperation could take many forms, from a network Benefit sharing with regard to flood protection of national institutions with an agreed information- could, therefore, be appropriately negotiated at xix Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks the tributary scale (i.e., between two countries), low flows into that system even without upstream rather than basinwide. Conversely, benefit sharing augmentation. A final important unknown is with regard to enhancing low flows for irrigation the economic value of augmented low flows in and ecosystems remains an appropriate issue for combating saline intrusion in the delta, and the basinwide discussions. Finally, models, such as those importance of the Ganges freshwater plume for developed for this study, could provide a new set the dynamics of currents and storm patterns in the of tools to help quantify basin impacts and support Bay of Bengal. More study of the morphology and information-based negotiations on hydropower ecosystems values in the Ganges delta is urgently development. needed. The basin also holds promising possibilities for A promising alternative to upstream water storage enhancing low-season water availability. Low flows reservoirs is the potential to augment low-season can be significantly augmented (potentially doubled flows by increasing groundwater utilization, within an in the dry months) as a co-benefit of developing appropriate energy-pricing and policy environment multipurpose storage reservoirs upstream. But the and in conjunction with a well-managed surface development of upstream storage reservoirs is a water system. In eastern Uttar Pradesh, enhanced costly undertaking, and this report suggests that groundwater use could produce additional storage storage investments would not be economically (and hence augment dry season water availability) justifiable solely – or even significantly – on on a scale comparable with the Himalayan dams, the grounds of their immediate contribution to but likely much more rapidly, at lower cost, and enhancing agricultural productivity in the basin. In more scalable. If upstream multipurpose dams fact there are large areas of waterlogged land whose are found to be economically, socially, and productivity could potentially be diminished if more environmentally justified by the bundle of benefits water were applied during the dry season, which is they can produce (predominantly hydropower), a time that usually allows for recovery. Upstream additional dry-season water could prove to be an storage alone will not modernize agriculture in the important co-benefit perhaps to complement more basin. A range of interventions is needed (and some immediate interventions in conjunctive use. are underway) to enhance agricultural productivity and support the livelihoods of poor farmers. These Still the basin faces persistent challenges, in interventions are anticipated to be beneficial particular in managing floods and sediment. Large regardless of the development of upstream storage. dams built to hold back flood waters high in the Himalaya have long been seen as the preferred Enhanced low-season flows may hold important strategy for managing the region’s devastating potential to sustain ecosystem services, particularly floods. But as an exclusive strategy, this is untenable. in the fragile Sundarbans (mangrove forests) of the The physical storage volume available in the Ganges delta. Yet the ecosystem values of increased mountains is simply too small to have a meaningful low flows downstream, e.g. in distributary rivers impact on basinwide floods, although reservoirs may such as the Gorai (which was once the mouth of provide some amelioration within tributaries. Flood the Ganges )—while possibly quite high—remain and sediment management is needed, but basinwide unsubstantiated. Interventions such as much- flood and sediment control is not possible. Effective less-expensive dredging through the sandbar that flood management requires regional information currently impedes flow of Ganges water into the and warning systems, coupled with a range of hard Gorai in the non-flood season could improve and soft, national and local level investments. xx The Ganges River Basin IBRD 39027 75°E 80°E 85°E 90°E HIMACHAL PRADESH PA K I S TA N THE GANGES RIVER BASIN Simla Jamnotri a Gangotri GANGES RIVER BASIN Ganges River Basin ELEVATIONS IN METERS: PUNJAB un CHINA MAIN RIVERS IN GANGES BASIN Main Rivers in Ganges Basin Yam Badrinath 4000 30°N SECONDARY Secondary RIVERS Rivers GANGES IN in BASIN Ganges Basin 2000 Dehra Dun a nda Alakn CITIES CitiesAND andTOWNS Towns 1000 Yamunanagar Saharanpur NATIONAL National CAPITALS Capitals 500 Roorkee Haridwar UTTARAKHAND 200 Karnal STATE StateBOUNDARIES Boundaries (INDIA) (Indian) 30°N l i INTERNATIONAL Boundaries InternationalBOUNDARIES Panipat Ranikhet haka Muzaffarnagar GLACIERS HARYANA Ma Nainital Seti Dandeldhura Haldwani i Rohtak Meerut Jumla al Ram Amroha rn Yamuna Ka i ga n Rampur ak Delhi DELHI Moradabad ga nd New Delhi Dhangarhi Gyirong a Gurgaon (Zongga) Tingri Faridabad Jahngirabad (Xêgar) Bareilly Gyirong Bulandshahr Sa Bisalpur rd Sallyan Dobzha Kali G Ga a n Baglung Gamba Pokhara ga Aligarh Nepalganj Nyalam Rongxar N E P A L Alwar Mathura Sitapur Kathmandu RAJASTHAN Bhairawa Bhimphedi n ru Bharatpur Kannauj SIKKIM Agra UTTAR A Jaipur Firozabad Rapti Ramechhap B H U TA N PRADESH Su gm Gh ag n Ko ur Ba ati si Kishangarh Etawah ha m l Lucknow ra Ta ba Bettiah Ilam am Go Gorakhpur Ch ma Faizabad si ti Siliguri Ya Kanpur Rajbiraj Ko m G Gwalior Ga Tonk un Biratnagar a nd an Ba d g ASSAM ak a gh Sin INDIA m Darbhanga as at i an B Betwa Muzaffarpur Ka Bhilwara al Saidpur ma mb Jaunpur Chhapra la a 25°N Ch Jhansi Ko Dinajpur Kota Ara BIHAR si Katihar Allahabad Patna MEGHALAYA Maha Rana Gan Varanasi ga Pratap Balurghat Udaipur Sindh Sagar n n Bhagalpur nanda Ke Gandhi So 25°N Sagar Dhasan Gaya Rewa Nawabganj a S on Rajshahi BANGLADESH B et w Parbati Nator Sa nk h Pad Sagar Govind JHARKHAND ma Ballabh Pabna Murwara Pant Sagar Dhanbad Ratlam Bhagi Halali WEST ra Faridpur Ujjain Riha Son Bhopal Asansol thi nd Durgapur BENGAL Go MADHYA Jesore rai Indore Barddhaman M PRADESH Gopalganj ad Khulna hum Barisal ati Kolkatta Pirojpurpur CHHATTISGARH 0 50 100 150 mi Patuakhali 0 50 100 150 200 km This map was produced by the Map Design Unit of The World Bank. s The boundaries, colors, denominations and any other information ge shown on this map do not imply, on the part of The World Bank ORISSA G a n o f t h e Group, any judgment on the legal status of any territory, or any endorsement or acceptance of such boundaries. MAHARASHTRA M o u t h s 75°E 80°E 85°E 90°E JANUARY 2012 xxi Executive Summary Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Finally, significant climate-change uncertainties Planners should develop regional information, remain in the basin. Current data and models give forecast, and warning systems; and national/local little clear evidence of what the future holds. But flood management strategies that combine both perhaps this uncertainty itself could be a reason hard and soft techniques. for enhanced cooperation. It appears that mean 3. The potential for hydropower development and hydrological variability in the future will be similar trade is significant (if sediment issues can be to the pronounced variability seen in the basin effectively managed), and should be simpler to today but extremes may well be greater. Greater negotiate than previously thought. climate extremes, however, would only strengthen 4. Agriculture planners should look for water the justification for the basic recommendations of storage underground, not just upstream. There this report. Investing in cooperative information is an opportunity for sustainable, conjunctive use management and modeling systems at the regional of significant additional groundwater resources level, along with a range of tailored interventions especially during the low-flow season. at the national and local levels, would enhance productivity and resilience in the Ganges Basin today Further Research as well as the capacity to manage climate change in In addition to refining and enhancing the current the future. models, this study points to several priority areas for further focused research. Key issues for future focus Implications and Opportunities should include: Four areas stand out as opportunities for action • Agricultural productivity in the Ganges plains based on the findings of the Ganges SBA: (1) • Ecosystem values of dry season water in the development of cooperative basinwide information Ganges delta systems and institutions; (2) flood management • Climate change in the basin and region using both hard and soft techniques; (3) hydropower development and trade; and (4) groundwater The Ganges SBA has used the best available development for irrigation. knowledge and tools to examine the fundamental strategic questions of the Ganges Basin. It has 1. Cooperative regional information systems, examined a number of commonly held perceptions ideally institutionalized in an inclusive river basin and concluded that many are unrealistic. It is committee or commission, could enhance the hoped this new knowledge will help the riparian productivity and sustainability of the river system states explore new visions and move ahead in a and help manage water related hazards. cooperative manner to sustainably manage this 2. If floods cannot be controlled, they must be extraordinary basin and its ecosystems for the benefit managed. Infrastructure alone is not the answer. of its present and future generations. xxii 1. Why Undertake A Strategic Basin Assessment? The Ganges is the most populous river basin in Basin vary dramatically within and among different the world. It presents both great opportunities and stakeholder groups, institutions, and countries. great challenges for its 655 million inhabitants whose daily lives rely on the water it provides. The The complexity of this river system and the extremes river system provides drinking water, agricultural of its landscape call for an evidence-based study water, hydropower generation, and navigational of the entire basin system. The very large, poor, and ecosystem services across more than 1 million and climate-vulnerable population of the basin square kilometers. underscores this need. There has been no common knowledge base or basinwide model that riparian But the river is destructive as well; devastating floods countries could use to explore options and facilitate and periodic droughts are routine and undermine cooperative planning at the basin level. This is a development. With growing populations and critical knowledge gap. increasing water withdrawals putting pressures on the river system, and climate change likely to intensify The objective of the Ganges Strategic Basin the seasonal variability, strategic examination of the Assessment (Ganges SBA) is to gain a better development potential of the basin’s water resources understanding of the dynamics of the river basin is urgently needed. from a system-wide perspective, by creating a knowledge base and suite of modeling tools that All countries in the basin benefit from the Ganges can be used to examine the potential impacts and suffer from its extremes; all could benefit more of development in the basin and support an and suffer less. Benefits from potential hydropower information-based dialogue within and between development and agricultural modernization remain riparian countries. untapped, while flood and drought management systems are inadequate to protect lives and This new information is envisaged to encourage, livelihoods. To better manage the Ganges – to rather than conclude, debate on critical sustain the river ecosystem, capture its potential transboundary management issues in the Ganges. benefits, and mitigate its mounting costs – requires It is clear that the current understanding of the enhanced regional knowledge and cooperation. basin is often fragmented, and that a system- wide perspective can provide important insights Development in the basin today is largely the result to enduring challenges across borders and within of incremental, project-by-project activities within riparian states. This report does not provide a each of the riparian countries. There has been roadmap for basin development, nor does it surprisingly little systematic regional research on examine the viability of individual investments, but it the basin’s development options and challenges does provide evidence of sufficient clarity to advance using modern analytical tools that go beyond sector, a more focused, information-based dialogue on country, or state analysis to examine the system-wide critical issues in a basinwide context. Importantly, it strategic questions that the basin faces. In addition, also highlights the value of a basinwide knowledge long-held perceptions of the current condition base and hence the importance of greater basinwide and the future development path of the Ganges information sharing, research and modeling – ideally 1 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks undertaken cooperative by the basin countries – to available and answer fundamental questions build a shared knowledge base for basin planning, about the potential and limitations of sustainable, enhancing agricultural and energy productivity, cooperative development in the basin. The improving disaster management and longer-term centerpiece of this work is the development of a set climate research. of nested hydrological and economic river basin models used to examine alternative scenarios across Recognizing the wealth of expertise in the basin, a range of possible Ganges futures, and a social this study was carried out by a World Bank team component that studies the social implications of in cooperation with several leading research water variability in the basin. This report does not organizations including the Institute for Water set out project-level cost benefit analyses of different Modeling (Dhaka), Indian Institute of Technology investment options. Nor is its scope adequate (Delhi), and the Indian Statistical Institute (Delhi). It to properly reflect the true range of cultural also benefitted from numerous consultations with and ecosystems values embodied in the basin. policy makers and opinion makers in Bangladesh, Nonetheless, the Ganges SBA marks an important India, and Nepal, as well as the members of the Abu early step in filling a critical knowledge gap. Dhabi Dialogue Group;1,2 and it draws on a vast collection of regional and international literature in Chapter 2 examines the river, its natural history, its which these crucial questions have been debated for usage today, its economic and institutional context, many years.3 and its emerging challenges. Chapter 3 sets out the analytical framework for the Ganges SBA. Chapter The Ganges Strategic Basin Assessment attempts to 4 provides a summary of findings and explores sort through the significant amount of information possible future implications. 1 Those who contributed to or were consulted during the development of this report have not necessarily endorsed it. 2 The Abu Dhabi Dialogue Group is a partnership of senior members of government, academia, and civil society from the seven countries that share the rivers of the Greater Himalayas, namely: Afghanistan, Bangladesh, Bhutan, China, India, Nepal, and Pakistan. It is an informal, non-attributable platform for discussions on water resources in the region, supported by the World Bank and the South Asia Water Initiative. Its vision is: ‘A cooperative and knowledge based partnership of states fairly managing and developing the Himalayan river systems to bring economic prosperity, peace and social harmony, and environmental sustainability from the source to the sea.’ 3 The literature on the Ganges is extensive and rich, representing a range of perspectives and a great deal of research. For example see Adhikari et al., 2000, Ahmad et al., 2001, Crow 1995, Dhungel and Pun 2009, Revelle and Lakshminarayan 1975, Rogers et al., 1989, Subba 2001, Verghese 1990 and others in the bibliography. 2 2. Overview The Ganges River Basin include Mount Everest at 8, 848 meters, to the flat Ganges plains at less than 100 meters above sea The Ganges rises in the Himalaya, travels level. The Deccan Plateau in the south of the basin is across the fertile Ganges plains, and flows into generally low elevation with hills up to 1,200 meters the Bay of Bengal through the Earth’s largest punctuated by rocky outcrops (see Figure 1). The mangrove ecosystem. In the western reaches of the eastern part of the basin is a flat delta characterized basin, tributaries flow south from the Himalaya and by the extensive and delicate Sundarbans mangrove north from the Deccan Plateau to form the main stem systems, or ‘beautiful forest.’ The basin is home to a of the Ganges. Within approximately 200 kilometers, host of rare and iconic species, including the snow the landscape plunges from an area with peaks that leopard, tiger, and Gangetic dolphin. Figure 1 Elevation Map of the Ganges Basin Elevation (meters) 0 25 250 500 1000 2500 5000 8800 Source: Based on Shuttle Radar Topography Mission (SRTM) data from the United States Geological Survey (USGS) 3 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks The total area of the basin is estimated at 1 million more than 2,500 kilometers to Bangladesh and square kilometers,4 covering all of Nepal, about a the Bay of Bengal. Its major tributaries include the quarter of the land area of Bangladesh, and nearly Himalayan tributary rivers of the Yamuna, Mahakali, one third of India. Karnali, Gandaki and Kosi and Mahananda rivers from the North. These northern Himalayan The Water System tributaries rise primarily in Nepal and India, with The tributaries and distributaries of the some portion of the Kosi, and to a lesser extent Ganges flow through Bangladesh, China, the Karnali, rising in China. From the south, the India, and Nepal. The Ganges originates in the tributaries of the Yamuna (the Chambal, Sindh, Gangotri Glacier at about 4,000 meters above sea Betwa, and Ken Rivers), and the Tonnes and Son level in the Indian state of Uttarakhand, and flows Rivers flow north into the main stem of the Ganges. Figure 2 Schematic of the Major Tributary Contributions of the Ganges Ganges Basin - Average Annual Flows Source: Based on data from Rao (1979). Annual Flow (BCM) < 10 20-25 40-45 65-75 200-350 10-12.5 25-30 45-50 75-100 350-400 12.5-15 30-35 50-55 100-150 400-600 15-20 35-40 55-65 150-200 > 600 4 WRI (2007) 4 Overview Figure 2 indicates the contributions of the major Figure 3 tributaries of the Ganges Basin. The Yamuna River, Creation of the Himalaya the Mahakali/Karnali/Ghaghra River, the Kosi River, and the main Ganga River are the system’s biggest flow contributors. The distributary system is also extensive. In India, the Damodar-Hooghly River system defines a distributary system that flows out to the Bay of Bengal near Kolkata. The main outlet of the Ganges, however, is in Bangladesh where the main stem of the Ganges (called the Padma in Bangladesh) merges with the Brahmaputra (called Jamuna in Bangladesh) before flowing into the Bay of Bengal through a 380-kilometer-wide delta. A continental collision created the Himalaya. The geomorphic history of the Ganges suggests that the basin was shaped by the collision of the Indian tectonic plate with the Eurasian plate about 20 million years ago (Figure 3). This event caused the formation of the Himalaya, which were uplifted by the collision. The Himalaya continue to grow as the Indian plate continues to push northward under the Eurasian plate causing it to rise. Some of the Ganges tributaries (e.g. Ganga, Karnali, Kosi) are ‘antecedent rivers’ that existed before the Himalaya were pushed up. These rivers rise north of the Himalayan range and appear to run ‘up and over’ the mountain range to drain in the south. These powerful rivers sustained their southward flow by cutting deep gorges even as the mountains rose up around them. The Himalaya are the ‘water tower’ of Asia, the source of the Ganges and many great rivers. The Greater Himalayan Region sustains the largest mass of ice outside of the north and south poles, and is therefore often referred to as the ‘third pole.’ From this region rise more than a dozen major rivers including the Ganges, Indus, Brahmaputra, Salween, Mekong, Yangtze, and Yellow. The rivers of the plateau flow west as far as Iran (where the Helmund River terminates in the swamps and lakes Source: Based on USGS (2011). of the Afghan-Iranian border), and flow east as far as the East China Sea where the Yangtze River empties near Shanghai. 5 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks The Ganges is a massive, meandering river years ago – the Ganges and Brahmaputra had system whose channel has gradually moved separate outlets to the sea (Figure 4). As a result of eastward. The morphology of the Ganges- the Ganges’s eastward movement it has abandoned Brahmaputra delta over the past several thousand a series of channels that no longer receive significant years suggests that the Ganges River course has amounts of water from the main river. The Hoogly moved eastward5 while the Brahmaputra has largely River, for example, was once the main outlet of the remained in its current course.6 According to early Ganges emptying into the Bay of Bengal at Calcutta.7 maps of the region – as recently as a few hundred The majority of the Ganges flow shifted eastward to Figure 4 Historical Map of South Asia with Separation of the Ganges and Brahmaputra Rivers Source: The Imperial Gazetteer of India (1909) 5 Allison 1998. 6 Kuehl et al., pp. 413-34. 2005. 7 The Hoogly River today receives controlled flows delivered by the Farakka Barrage. 6 the Gorai River system in southwest Bangladesh, and Ganges by blocking the northerly push of the eventually to its current primary outlet in southeast monsoon and confining it to the subcontinent. Bangladesh. Even after the merger of the Ganges with Simulations from a Global Circulation Model the Brahmaputra, the while Ganges-Brahmaputra- (GCM) developed by the National Center for Meghna system continues to move eastward, with a Atmospheric Research (NCAR) show how the South corresponding movement of the active delta. Attempts Asian monsoon is contained in the subcontinent by to control this massive moving river have been likened the Hindu Kush–Himalaya range (Figure 5). In the to ‘putting handcuffs on a snake.’8 pre-monsoon period (April) there is little precipitation over South Asia. In the monsoon period (August) The Ganges river system is a complex interplay the subcontinent is draped in cloud, with a sharply of monsoonal runoff, glacier and snow melt, delineated northern edge that follows the arch of the and groundwater resources. The system‘s Hindu Kush–Himalaya range. complex natural features – monsoon rains, the Himalayan mountain range, and its vast plains and The South Asian monsoon system largely delta – make it difficult to comprehend. Added to defines the climate and hydrology of the the diversity and extremes of the landscape is a Ganges river system. Two arms of the South pronounced seasonality. A systemwide understanding Asian monsoon sweep across the continent along of the hydrology and climate is fundamental to either coast of peninsular India (Figure 6). During effectively managing virtually any stretch of the river. an average hydrological year, some 1,200 billion cubic meters of precipitation falls in the basin. The Himalayan mountain range plays a key Of this, about 500 billion cubic meters flows into role in the hydrological environment of the the river system and becomes the Ganges River Figure 5 Confinement of the South Asian Monsoon Pre-Monsoon (April) Monsoon (August) Source: National Center for Atmospheric Research (NCAR)9 8 Don Blackmore, personal communications. 9 Atmospheric configuration and simulation by James Hack (Oak Ridge National Lab), Julie Caron, and John Truesdale, National Center for Atmospheric Research (NCAR). Visualization by James Hack and Tim Scheitlin, copyright 2007, NCAR. 7 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks flow. The remaining 700 billion cubic meters of Figure 6 water is captured in the landscape, recharging Path of the South Asia Monsoon groundwater or returning to the atmosphere through evapotranspiration. The monsoon brings heavy rains three months a year. The monsoon delivers about 80 percent of annual rainfall in just three months of the year (mid-June through mid-September) with a corresponding peaking in the river flows in July to October. Figure 7 depicts the flow of the Ganges at Farakka Barrage near the India-Bangladesh border. The peak is caused by intense monsoon rains from mid-June through mid-September, against the relative low flows for the remainder of the year. April and May are the lowest flow months with negligible rainfall and a low base flow into the system. In addition to the significant seasonal variation within years, there is also great variability between years (especially in monsoon months), depicted by the vertical lines that indicate the minimum and maximum flows recorded for each month. Figure 7 Seasonal and inter-annual variability of flow in the Ganges at Farakka. Data from Global Runoff Data Centre 1949-1973 200 – 180 – 160 – 140 – Flow (BCM/month) 120 – 100 – 80 – 60 – 40 – 20 – 0– l l l l l l l l l l l l Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Min Mean Max 8 Overview The non-monsoon months are generally hot and delta areas of the basin, and lowest (less than 250 dry. Temperatures are high most of the year in most millimeters annually) in the Thar desert of Rajasthan of the basin except for the Himalaya (Figure 8). in the west. There is general scientific consensus Precipitation is highest (more than 2,000 millimeters that climate change will increase temperatures annually) in the eastern Himalayan belt and in the throughout the basin, leading to impacts such Figure 8 Temperature and Precipitation in the Ganges Basin Temperature Annual Average Temperature (°C) <0 10 - 15 21 - 22 24 - 25 27 - 28 < 300 900 - 1200 1800 - 2100 > 2700 0-5 15 - 20 22 - 23 25 - 26 28 - 29 300 - 600 1200 - 1500 2100 - 2400 5 - 10 20 - 21 23 - 24 26 - 27 29 - 30 600 - 900 1500 - 1800 2400 - 2700 Source: Based on CRU TS 2.0 climate dataset from the British Atmospheric Data Centre (BADC), University of East Anglia. 9 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Precipitation Annual Average Precipitation (mm/year) <0 10 - 15 21 - 22 24 - 25 27 - 28 < 300 900 - 1200 1800 - 2100 > 2700 0-5 15 - 20 22 - 23 25 - 26 28 - 29 300 - 600 1200 - 1500 2100 - 2400 5 - 10 20 - 21 23 - 24 26 - 27 29 - 30 600 - 900 1500 - 1800 2400 - 2700 Source: Based on CRU TS 2.0 climate dataset from the British Atmospheric Data Centre (BADC), University of East Anglia. as increased evaporation, increased crop water Large areas of the basin routinely suffer from both requirements, changes in snow formation and melt, droughts and floods (Figure 9). Floods already and changes in glacier accumulation and melt. take a significant toll on lives and livelihoods in the Nepal lowlands known as the terai, as well as The basin’s climate is highly variable, prone in Bangladesh and the Indian states of Bihar and to both flood and drought. Climate variability eastern Uttar Pradesh. Floods account for 90 percent is seen most dramatically in floods, droughts, and of the economic cost of natural disasters in Nepal. the uncertain timing of the onset of the monsoons. See Box 1 for efforts to manage floods. 10 Figure 9 Drought and Flood Affected Populations in the Ganges Basin Exposure to Droughts Population 2010 exposed (Thousands of people per year) None / No Data 0.25 - 0.5 10 - 25 500 - 1000 None 0.25 - 0.5 10 - 25 < 0.025 0.5 - 1 25 - 50 1000 - 2500 < 0.025 0.5 - 1 25 - 50 0.025 - 0.05 1 - 2.5 50 - 100 2500 - 5000 0.025 - 0.05 1 - 2.5 50 - 100 0.05 - 1 2.5 - 5 100 - 250 0.05 - 1 2.5 - 5 100 - 250 1 - 0.25 5 - 10 250 - 500 1 - 0.25 5 - 10 250 - 500 Source: Based on data from Global Risk Data Platform, UNEP/GRID (2011). Glaciers contribute a small share of the total North America where glacial melt contributes to Ganges flow. Glaciers and snow provide water low summer flows, the Himalayan glaciers melt storage that contributes to the perennial flow of during the monsoon season when temperatures these highly seasonal river basins. It should be are highest but rainfall is also heaviest. In the noted, however, that in contrast to Europe and Ganges Basin, glacier melt water accounts for just 2 11 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Exposure to Floods Population 2010 exposed (Thousands of people per year) None / No Data 0.25 - 0.5 10 - 25 500 - 1000 None 0.25 - 0.5 10 - 25 < 0.025 0.5 - 1 25 - 50 1000 - 2500 < 0.025 0.5 - 1 25 - 50 0.025 - 0.05 1 - 2.5 50 - 100 2500 - 5000 0.025 - 0.05 1 - 2.5 50 - 100 0.05 - 1 2.5 - 5 100 - 250 0.05 - 1 2.5 - 5 100 - 250 1 - 0.25 5 - 10 250 - 500 1 - 0.25 5 - 10 250 - 500 Source: Based on data from Global Risk Data Platform, UNEP/GRID (2011). percent of annual flow in the main river system.10 the glaciers’ contribution to the total measured (In contrast, the Himalayan glaciers that feed stream flow is about 30 percent, whereas in the Indus provide some 20–30 percent (e.g., Nepal’s Likhu Khola Basin it is just 2 percent. The Bolch et al., 2012; Yu et al., 2013.) Within the average for all Nepal’s rivers is approximately Ganges Basin, glacier contribution to stream flow 10 percent. A better understanding of this glacier varies enormously and glacier melt does play system will be essential to protecting vulnerable an important role in many glaciated sub-basins. communities and managing climate adaptation in In Nepal’s Budhi Gandaki Basin, for example, South Asia. 10 Alford and Armstrong 2010. 12 Box 1 Enduring Challenge of Floods Tackled by Modern Technologies Bangladesh has piloted a range of innovative approaches to flood management in recent decades, including innovative forecasting (hydrologic forecasts based directly on weather forecast ensembles), modeling (using a suite of hydrologic and hydrodynamic modeling tools), and communications (using cell phones and community warning systems). These innovations have been highly effective in reducing flood losses. The Indian state of Bihar recently created a new Flood Management Information Systems Center to improve its capacity for flood forecasting and response. Nepal is investing in crucial real-time information that will strengthen forecasting and warning capacity. Real-time data from Nepal is routinely shared with India’s Central Water Commission to issue flood warnings in downstream areas. National systems are being updated in all countries. Significant opportunities remain, however, to improve data acquisition, public data access, forecasting techniques using integrated ground and satellite systems, modeling, and communication systems. In addition to technological innovations, robust institutional arrangements both within and among basin countries will be needed to diminish annual losses of lives and livelihoods caused by floods. Sedimentation is an enduring challenge in the Table 1 Ganges Basin. The Ganges Basin was formed as Average Annual Suspended Sediment Load eroded materials from the Himalaya were deposited River Average Annual to fill what was once a cape and is now the Ganges Suspended Sediment plains, creating large floodplains and deep aquifers. Load (million tonnes) The Ganges is one of the most sediment-laden river systems in the world, with a silt load that is an order Amazon 1,200 of magnitude larger than most rivers. Table 1 shows Yellow (Huang He) 1,080 the world’s top ten rivers in terms of suspended Ganges/Brahmaputra 1,050 annual sediment load; together they account for Yangtze (Chang Jiang) 480 about 30 percent of the world total.11 The Ganges- Irrawaddy 260 Brahmaputra River systems carry more than 1 billion Magdalena 220 tonnes of silt12 to the delta every year. This is an Mississippi 210 extremely high sediment load, and one that is not Godavari 170 particularly fertile.13 It is important to understand, Mekong 160 however, because the dynamics of erosion and Orinoco 150 accretion have been constantly redefining the coastal Source: Adapted from: Milliman and Mei-e Ren 1995. contours of Bangladesh and the Indian state of West Bengal. 11 Milliman and Mei-e Ren 1995. 12 Kuehl et al., 2005. 13 Subramanian and Ramanathan 1996. 13 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Water Management in the Basin a binding constraint. A recent study by the Water Agriculture dominates both surface and for Food Challenge Program of the Consultative ground water use in the basin. Irrigation Group on International Agricultural Research (CGIAR) represents about 90 percent total water use in found that in the eastern basin (Uttar Pradesh, Bihar, the Basin, though increasing demand from urban and West Bengal in India, eastern Nepal terai, and centers and industry can be expected to shift this all of Bangladesh) ‘Rich alluvial soils and abundant balance in the coming years. The basin is home to surface and groundwater provide high agricultural some of the largest irrigated areas in the world. The potential; however, for a variety of reasons including state of Uttar Pradesh alone has about 9 million inadequate drainage, unfavorable land tenure, hectares at least partially irrigated with surface water, and inadequate infrastructure and institutional and an additional 8 million hectares that rely solely arrangements including marketing, combined rice- on groundwater (Figure 10). wheat productivity is estimated to be just 4-8 tonnes per hectare per year.’14 Wheat yields in the Indian Agricultural productivity in the basin is low, State of Bihar, part of West Bengal and Bangladesh however, and water availability is not always are as low as 0.70 to 1.58 tonnes per hectare.15 Figure 10 Irrigation in the Ganges Basin Irrigated Areas Surface Ground Conjunctive Use Source: Based on Global Irrigated Area Map by IWMI. 14 Sharma 2008. 15 Cai et al., 2010. 14 Overview Although additional water in the dry season may be a groundwater permits cultivation of a second crop in welcome resource for some communities (and likely the dry season. Groundwater is also used to buffer of significant value to ecosystems), it is clear that against the erratic surface water supply. Much of upstream dams alone will not modernize agriculture this conjunctive use is unplanned, undertaken by in the Ganges. National-level investments and individual farmers using primarily deep (electric) policy reforms are needed to enhance agricultural tubewells in the western part of the Ganges Basin, productivity, which would benefit poor farmers even in and shallow (diesel) tubewells in the east. the absence of upstream water storage development. Although some of the older irrigation systems (e.g. Extensive surface irrigation schemes have in western Uttar Pradesh) are in good condition been developed in the Ganges plains, with reasonably good productivity, much of the particularly in India. The surface irrigation canal surface irrigation system is in poor condition (e.g. network in the basin (Figure 11) has developed in in eastern Uttar Pradesh) and the soil suffers from various phases, starting primarily in the British period waterlogging and poor productivity. In Bangladesh, (mid-19th to mid-20th centuries) for example, with groundwater irrigation with shallow tubewells helped the Upper Ganga Canal system. But the area is not make the country self-sufficient in food production, solely surface irrigated. Extensive conjunctive use of although challenges (including naturally occurring Figure 11 Irrigation Canals in the Ganges Basin Canal Source: Based on data from RMSI Pvt. Ltd. 15 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks arsenic in the groundwater) remain in the continuing 1,000 dams in its 1 million square kilometers with management of water. heights varying from 10 meters to 260 meters (Figure 12). Only five of them are more than 100 To a large extent, the surface and meters tall. The system’s surface storage capacity groundwater irrigation systems in the Ganges is about 55 billion cubic meters, with about 36 plains are interlinked. The surface irrigation billion cubic meters currently active. This storage canals often serve to recharge the groundwater capacity, compared with an annual system flow and the groundwater systems are often used to of about 420 billion cubic meters (and rainfall supplement surface water, especially in eastern Uttar approaching three times that value), is only 13 Pradesh. Eastern Uttar Pradesh also has large areas percent of the total water available annually. As where pre-monsoon groundwater levels are either a point of reference, many developed rivers have at or just below the surface, resulting in waterlogged storage-to-annual-flow ratios of 100–200 percent. areas with poor productivity. Thus, there is very little capacity to regulate the system to reduce flooding, augment low flows for There is little active water storage in the winter (rabi) irrigation or operate storage-backed system today. The Ganges Basin has more than hydropower production. Figure 12 Major Dams and Barrages in the Ganges Basin Water infrastructure Barrage Dam Ganges basin Rivers Lakes Country boundaries State boundaries 16 Overview The basin offers significant opportunities Himalaya – the Pancheswar Dam on the Mahakali for additional water development and use. River, the Chisapani Dam on the Karnali River, and the The Ganges Basin has been extensively developed Sapta Kosi High Dam on the Kosi River (Figure 13) for irrigation, but a range of additional water – have long been considered for development. The development opportunities remain. The Himalayan combined installed hydropower generation capacity of Mountains offer potential multipurpose dam sites, the these three dams would be roughly 30 times Nepal’s plains could support enhanced irrigation, and deep current total installed capacity. aquifers with good-quality groundwater resources could be tapped.16 Although many of these options Embankments have become a pervasive could be pursued by riparian countries, some would feature of the Ganges landscape. Construction require effective regional cooperation. Many such of embankments to control flooding began on a options (e.g. multipurpose dams in the Himalaya) large scale began during British rule. The majority of have been discussed for decades with little action. In embankments, however, were built following India’s particular, three proposed large dam sites in the Nepal independence.17 Between 1954 and 1997, around Figure 13 The Sites and Simulated Reservoirs of the Three Largest Dams under Consideration in Nepal Ganges Basin International boundaries State boundaries Rivers Source: Using Google Earth imagery. 16 See SMEC 2009 and Sharma et al., 2008. 17 Mishra 2008. 17 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks 16,200 kilometers of embankments were constructed Poverty is widespread, with average GDP per in India, and around 7,555 kilometers (including capita under $2 per day and poverty rates around 4,000 kilometers of coastal embankments) were around 30 percent. In Nepal, where the entire constructed in Bangladesh. This construction resulted in population resides within the basin, average GDP per the protection of 17 of the 40 million hectares prone to capita is $470 and the proportion of the population floods on the Ganges plain in India,18 and 3.5 million with a standard of living below the poverty line is 31 hectares in Bangladesh, about a quarter of its total percent.22 In India and Bangladesh, poverty in the land area.19 In Nepal, only a few hundred kilometers of Ganges Basin districts is higher than the national embankment has been constructed.20 average (Figure 14). India’s 2005 national poverty estimates show 27.5 percent23 of its population living Socioeconomic Context below the poverty line; however, in the vast majority The Ganges is the most populous river of states with some or all districts inside the Ganges basin in the world, home to more than 655 Basin, these percentages were higher, rising to million people in its total area of 1 million square around 40 percent in Bihar, Chhattisgarh, Jharkhand, kilometers.21 As a point of comparison, the next most Madhya Pradesh, and Uttarakhand.24 Poverty populous basin is China’s Yangtze River Basin with estimates for Bangladesh also show those districts in some 400 million people and considerably more the basin to have a slightly higher poverty rate than land area. The Indian state of Uttar Pradesh, which the national average. The districts of Bangladesh in falls entirely within the Ganges Basin, has roughly the Ganges Basin recorded total poverty rates (upper the same population as Brazil, the world’s fifth most poverty line) of 44 percent, as compared with the populous country (Table 2). national average of 40 percent.25 Table 2 Population Profile of the Ganges River Basin Country Basin Average Basin Area % of % of Basin % of % of Basin Population Population (sq. km) Country Area Country Population in 2000 Density per Area within within the Population in Country (2011 est.)a sq. km the Basin Countryb within the Thousands (2011 Basin Nepal 28,504 est.)194 147,184 100 12 100 4 Bangladesh 50,680 1,285 39,452 27.4 3 38 8 India 576,344 575 1,002,609 30.5 84 47 88 Total 655,528 551 1,189,246 Note: a. Population estimates include the total population of Nepal, and the populations of districts within the Ganges Basin for Bangladesh and India. Nepal’s 2011 population is estimated using the 2001 census figures and the presumed decadal growth rate calculated in that census. Estimates for Bangladesh use relevant district level populations from the 2001 census and the decadal growth rates for 2001-2011 from the 2001 census. Estimates for India use district-level data from the 2001 census and assume 2011 preliminary state population growth estimates and uniform growth across districts within a state (district level population growth rates are not available.) b. The residual basin area is in China. 18 NCIWRDP, 1999: 129, as cited in Bandyopadhyay 2009 19 Islam and Bari 2008. 20 Dixit 2009. 21 WRI 2007. 22 World Bank 2011. 23 Based on Uniform Recall Period consumption, in which the consumer expenditure data for all the items are collected for a 30 day recall period. Poverty lines in this case vary by state. Indian National Planning Commission. 24 Only Delhi, Haryana, and Himachal Pradesh had lower than average proportions of the population living below the poverty line (estimated at around 14.7, 14, and 10 percent, respectively) and Rajasthan and West Bengal were near the national poverty line at 22 and 24 percent, respectively. 25 Poverty maps produced by Bangladesh Bureau of Statistics, World Bank, World Food Programme, 2007. 18 Overview Figure 14 GDP Per Capita, 2005 GDP per capita in 2005 (Nominal, in USD) < 250 500 - 700 1000 - 1500 > 2000 250 - 500 700 - 1000 1500 - 2000 Source: Based on data from Central Statistical Organization, India and WDI 2010 (World Bank) The basin is one of the most densely populated areas more than twice the (already quite high) average on earth. Average population density in the basin is population density for the basin as a whole. 551 people per square kilometer, more than 10 times the global average (Table 2 & 3 and Figure 15). The huge population of the Basin, combined Bangladesh’s total population is similar to Russia’s, with pervasive poverty and extreme population but its population density is 120 times greater. density, mark the Ganges Basin as a unique global challenge. Population levels and poverty In the Indian states of the basin, those districts that rates in the basin approach those of Sub-Saharan fall within the basin boundaries have an average Africa. Figure 16a compares the total populations of population density more than five times that of the the Ganges Basin and Sub-Saharan Africa. In 2005, districts in the same state but outside the basin the population of the basin was equivalent to three- boundaries. Population density is particularly high quarters of the entire population of Sub-Saharan in the eastern basin where many districts have Africa.26 Figure 16a also shows the very large 26 The ratio for 2010/2011 remains virtually unchanged at 76 percent. 19 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Overview Figure 15 Population Density in the Ganges Basin Ganges Basin - Population Density Population Density in 2010 (persons per sq. km) 0 - 10 11 - 50 51 - 250 251 - 500 500 - 1000 1001- 2000 > 2000 Source: INRM (2011). proportion (over 70 percent) of the two populations In Nepal, 82 percent of the population is rural.27 In that live on less than $2 per day. The $2 per day India’s basin districts the figure is similar, around 80 headcount poverty rates differ by less than 10 percent. percent (which is higher than the national average In Sub-Saharan Africa, however, population density of 72 percent).28 In Bangladesh, 79 percent of the is very low, while in the Ganges Basin, population national population is classified as rural. The rural density is extremely high, see Figure 16b. populations of all three countries face higher poverty rates, on average, than their urban counterparts. The Basin today is overwhelmingly rural, but it However, population growth in the basin is high and is growing ever more populous and urbanized. the region is rapidly urbanizing, with the growth of 27 World Bank 2009. 28 2011 estimates. 20 Table 3 Population Density in the Ganges Basin Country Basin Population Population density (States) (2011 estimates in thousands) (people/km2) Nepal 28,504 194 Bangladesh 50,680 1,285 India 576,344 575 (Bihar) 103,681 1,101 (Chhatisgarh) 6,484 178 (Delhi) 16,677 11,245 (Haryana) 16,970 772 (Himachal Pradesh) 1,426 99 (Jharkand) 27,946 421 (Madhya Pradesh) 56,848 250 (Rajasthan) 45,402 288 (Uttar Pradesh) 199,429 828 (Uttarakhand) 10,108 189 (West Bengal) 91,372 1,030 Total 655,528 551 Figure 16a Figure 16b Comparison of Population Living on Less Poverty rates and Population Density in the Ganges than $2/day in the Ganges Basin and basin and Other Regions Sub-Saharan Africa % of People / Population km2 800 – 80 – – 600 700 – 70 – – 500 600 – 60 – – 400 Population (millions) 500 – 50 – 400 – 40 – – 300 300 – 30 – – 200 200 – 20 – – 100 100 – 10 – 0– 0– –0 Ganges Basin Sub-Saharan Africa Europe & Latin Sub- Middle East East South Ganges Central America & Saharan & North Asia & Asia Basin >$2/day <$2/day Asia Caribbean Africa Africa Pacific Population Density – People per sq. km of land area % Population living under $2 a day (PPP) Note: The chart is based on illustrative poverty estimates for the Ganges Basin. The estimates are for 2005. Population estimates are for all of Nepal and the Ganges Basin districts in India and Bangladesh. Population numbers for India and Bangladesh are mid-census estimates from national sources and for Nepal from the WDI. Poverty estimates use a $2 Purchasing Power Parity (PPP) poverty line for comparability across countries. Since virtually all of Nepal lies within the Ganges Basin, the poverty estimate (% of people below the $2 PPP poverty line for 2005) is taken directly from the WDI. For India and Bangladesh, however, only some districts lie within the Basin and therefore estimates were made using state-level poverty estimates ($1.03 poverty line) available from national sources (Ghani, 2010). The state level estimates were extrapolated to a $2 poverty line assuming that the national level difference between $1 and $2 PPP in poverty obtained from WDI is also a valid approximation in all the states. It was also assumed that state level poverty rates apply to the districts of that state which fall within the Basin. 21 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks megacities such as Delhi, Kolkata, and Dhaka, and Population and land use changes have a number of secondary cities as well. By 2025, the transformed the landscape of the basin. population of Delhi alone is anticipated to be 28 Forests and wetlands have all but disappeared in million – equivalent to the total national population the plains, replaced by increasing urban areas and of Nepal today (Figure 17). the expanded agricultural land needed to feed the burgeoning population (Figure 19). These changes Sprawling urban areas with expanding ecological also place significant pressures on water systems as footprints are becoming a dominant feature of the agricultural and urban/industrial water demands rise. Ganges plain (Figure 18). This trend will lead to changes in water demand and use patterns in the basin Pollution is a growing concern for those that could have significant local tradeoffs with other uses. living in the basin. Rapid urbanization and Figure 17 Urban Population and Growth in the Ganges Basin Population in 2000 Population in 2010 Population in 2025 Source: Visualization based on World Urbanization Prospects 2009 update, United Nations Population Division. 22 Overview Figure 18 Delhi City Expansion over 25 Years DELHI : Increase in population of 4.2 million and 60,000 hectares of agricultural land lost Delhi 1974 Delhi 1999 Land cover derived from Landsat Land cover derived from Landsat MSS acquired May 8, 1974 TM acquired May 21, 1999 Forest Agricultural Grassland Wetland Barren Water Urban Source: Harvard University, courtesy of Professor Peter Rogers. Figure 19 Land Use in the Ganges Basin Irrigated croplands Rainfed croplands Mosaic Croplands/Vegetation Mosaic Vegetation/Croplands Closed to open broadleaved evergreen or semi-deciduous forest Closed broadleaved deciduous forest Open broadleaved deciduous forest Closed needleleaved evergreen forest Open needleleaved deciduous or evergreen forest Closed to open mixed broadleaved and needleleaved forest Mosaic Forest-Shrubland/Grassland Mosaic Grassland/Forest-Shrubland Closed to open shrubland Closed to open grassland Sparse vegetation Closed to open broadleaved forest regularly flooded (fresh-brackish water) Closed broadleaved forest permanently flooded (saline-brackish water) Closed to open vegetation regularly flooded Artificial areas Bare areas Water bodies Permanent snow and ice Source: ESA Globcover 2009, European Space Agency. 23 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks industrialization in recent years have caused high River Basin Authority (NGRBA) and has launched a levels of pollution in many parts of the Ganges major initiative with World Bank support to reduce Basin, especially in the Yamuna near Delhi and the pollution of the Ganga River. Natural arsenic in Ganga between Kannauj and Varanasi (Figure 20). groundwater is an increasing challenge, not only in The levels of fecal coliform are some of the highest Bangladesh and West Bengal, but in many parts of found anywhere in such a large river. Domestic the Ganges plains. sewage is the major source of contamination. Newer pollution sources such as solid waste, industrial Physical exposure to water-related risks is sources (e.g. tanneries near Kanpur, distilleries, closely linked with social vulnerabilities in paper mills) and agricultural nonpoint sources (from the region. Poor and socially marginalized people the extensive agrochemical use in the agricultural have less access to institutions and services, limited areas) are increasing, adding a new dimension to income opportunities, and fewer assets and means this growing problem. To address this challenge, the to rebuild their lives after floods, droughts, and Government of India created the National Ganga storms. These least-advantaged populations tend Figure 20 Surface Water Quality in the Ganges Basin Fecal Coliforms (Count in thousands per 100 mL) < 50 0.1 - 0.5 1-5 10 - 25 50 - 100 0.05 - 0.1 0.5 - 1 5 - 10 25 - 50 > 100 Source: Based on data from the Central Pollution Control Board (Government of India). 24 Overview to live in areas with higher physical risks, while Studies in Bangladesh have shown that women and those with economic options tend to move away children are 14 times more likely than men to die during from the most physically insecure spaces. Typically, natural disasters.31 Recovery can also be particularly disadvantaged groups settle in the most drought- or difficult for women due to intra-family coping flood-prone areas and occupy the least productive mechanisms. In focus group discussions undertaken land. They do not have access to irrigation schemes for this study, women claimed that in the aftermath of but instead rely on unpredictable rainfall for a disaster, when there was limited food available to agricultural production. their families, they were often the last to eat.32 The poor and socially marginalized are often Institutions in the Basin overlooked during relief and reconstruction efforts. Social prejudice against the poor, lower castes, and Treaties women may impact the way relief is distributed. Deteriorating water quality also poses particular risks The basin has a half-century history of for the poor. Water pollution has a disproportionate29 incremental bilateral treaties, but no impact on those, generally the poor, who rely on the basinwide or multilateral treaties. Despite Ganges for their livelihoods (fishing, agriculture, or widespread perceptions of significant opportunities religious tourism) as well as for their personal and for cooperative development,33 only a few treaties domestic uses (bathing and household uses). and only bilateral ones have been signed between Ganges Basin riparians. Skewed sex ratios in the Basin suggest that women are substantially disadvantaged. Sex The first treaty, on the Kosi River, was signed ratios, the number of females per 1.000 males, are between India and Nepal in 1954. The treaty was often used as an indicator of gender parity because developed to attenuate routine devastating floods skewed sex ratios suggest inequity in survival and in the Indian state of Bihar. Soon after its conclusion longevity between genders. The sex ratios within in 1954, however, the treaty came under criticism the Ganges Basin are troubling. In Nepal, the sex in Nepal where it was perceived as inequitable, ratio is estimated to be 960, and in Bangladesh, for in part because it called for the construction of the districts in the basin, it is 961.30 Initial estimates embankments to contain the course of the Kosi, as from the 2011 Indian census show that while India’s well as the construction of the Kosi Barrage, both of national sex ratio has improved (to 940 from 917 in which are entirely within Nepal. The land associated 2001), it has worsened or stayed the same for the with the embankments and barrage (the built and Indian states in the Ganges Basin. inundated areas) was to be acquired by Nepal and then ceded to India. The Kosi Treaty was amended Women in the Basin are particularly vulnerable in 1966 so that the land would be leased to India to water- and climate-related hazards. Estimates rather than ceded, but many still felt the terms of have shown that women, the poor, and other socially that lease (199 years at a nominal annual rate) were marginalized groups face the highest risks from inequitable and that it did not properly compensate morbidity and mortality because of natural disasters. the loss of fertile farmland in Nepal. 29 Rabinowitz 2008. 30 BBS 2001. 31 Neumayer and Plumper 2007. 32 Ibid, and confirmed in Focus Group Discussions in Bihar and West Bengal and in Bangladesh (July-August 2010). 33 See, for example, Adhikari et al., 2000, Ahmad et al., 2001, Crow 1995, Dhungel and Pun 2009, Revelle and Lakshminarayan 1975, Rogers et al., 1989, Subba 2001, Verghese 1990. From the press see Rajeev Ranjan Chaturvedy and David M. Malone, ‘Hydro-diplomacy: a neglected opportunity for Nepal and India,’ The Hindu, June 28, 2011; Sadiq Ahmed, ‘Possible gains from regional cooperation,’ The Financial Express (Bangladesh), December 14, 2010; ‘Nepal-B’desh to cooperate on flood control,’ Kathmandu Post, November 1, 2004; ‘Data sharing to reduce water induced disasters’, Kathmandu Post, November 30, 2004. 25 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks The second treaty between India and Nepal, Although the basin’s treaty history shows a the Gandaki Treaty, was signed in 1959 with a progression toward good practice principles, it has focus on flood control, irrigation, and power. The been marked by contention and continues to cause Gandaki River, like the Kosi, brought annual floods some unease among the riparian countries.34 that damaged crops and property in both Nepal and India. This treaty is considered more favorable Outside the basin, but potentially relevant, to Nepal than the Kosi Treaty. Nevertheless, it, too, is the history of the Indus Treaty. The 1947 was met with strong objection in Nepal. Unlike partition of India and Pakistan made the Indus an the Kosi Treaty, the Gandaki Treaty has not been international river. The dependence of both countries amended. on its waters necessitated a cooperative resolution. After years of inconclusive bilateral negotiations, The third treaty between India and Nepal was the the World Bank was asked to mediate. Early Mahakali Treaty that entered into force in 1997. progress was made in agreeing on procedures, The Mahakali River runs north to south along commonalities, and on the total amount of water Nepal’s western border with India. The Mahakali available and under discussion. Still, the conflicting Treaty emphasized an integrated approach to water claims of the two states created a stalemate. In resources development, benefit sharing, and the 1954, the World Bank proposed allocating the need to revisit earlier activities and agreements western rivers (Indus, Jhelum and Chenab) to based on present needs. It also included provision Pakistan and the eastern rivers (Ravi, Beas and Sutlej) for the development of the Pancheshwar Dam to India. This proposal was eventually accepted (which remains unbuilt). It aimed to maximize the by both sides. To deliver equitable shares of water benefits for both countries, an approach that was to both countries, however, Pakistan had to invest absent in the Kosi and Gandaki treaties and is heavily in link canals, diversion structures, and dams. generally considered consistent with international The World Bank assisted the parties by negotiating good practice. But again, the treaty was met with a cost-sharing arrangement for these pivotal civil widespread controversy in both India and Nepal. works and mobilizing the necessary finance. The Indus Waters Treaty was signed on September 19, India and Bangladesh entered into a number of 1960. The World Bank is a signatory, though not a successive agreements from 1975 through 1988. guarantor, of the treaty.35 After prolonged negotiations, the two countries concluded a treaty on sharing the Ganges in 1996. Institutions The Ganges Treaty, whose provisions dictate inter alia the allocation of flows at Farakka Barrage (at Each of the Basin states has a unique the Indo-Bangladesh border), has also raised equity institutional structure for managing concerns in some quarters. The Ganges Treaty, transboundary waters. In Nepal, a dedicated allocated the low dry-season flows at Farakka transboundary waters office was established in between India and Bangladesh, but did not specify 2010 under the Water and Energy Commission how much water India could withdrawn upstream Secretariat (WECS)36 to support the government’s from Farakka Barrage, nor did it address high-flow dialogue on transboundary waters. In India and (flood) issues. Bangladesh, ministries of water resources hold the 34 Salman and Uprety 2002. 35 Sadoff et al., 2008 36 The Water and Energy Commission (WEC) was established with the broad objective of developing water and energy resources in an integrated and accelerated manner. The Water and Energy Commission Secretariat (WECS) is a permanent secretariat of WEC, established in 1981 under the then Ministry of Water Resources (MOWR) and is currently under the Ministry of Energy since the 2010 split of the MOWR into the Ministry of Energy and Ministry of Irrigation. The primary responsibility of WECS is to assist the Government of Nepal in the formulation of policies and planning of projects in the water resources and energy sectors. 26 Overview mandate for transboundary waters. Within India, numerous Indo-Nepal technical committees, a three- it is notable that jurisdiction over water resources tiered mechanism was agreed by the JCWR in 2008 management resides with the country’s 28 states. comprising: River basin management organizations are set up only for specific purposes such as constructing and 1. Joint Ministerial Level Commission on Water managing large interstate multipurpose projects or Resources (JMCWR) at the level of ministers of pollution abatement. The first basin-level initiative to water resources of India and Nepal, manage a large interstate river for water quality and 2. (continued existing) Joint Committee on Water environmental protection, the National Ganga River Resources (JCWR) at the level of secretaries of Basin Authority (NGRBA), was constituted in 2009 India and Nepal, and under the Environment Protection Act. The NGRBA 3. Joint Standing Technical Committee (JSTC) at was given a multi-sector mandate to ensure pollution the level of chairman, to rationalize technical abatement in the Ganga by addressing both water committees and subcommittees under JCWR quantity and quality aspects and by adopting a related to flood management, inundation river basin approach. Its powers are significant and problems, and flood forecasting. combine regulatory and developmental functions. The Government of India intends to develop the Regional bodies NGRBA as a model for other rivers in the country.37 Outside of these official bilateral mechanisms, there are no organizations with a clear mandate to Bilateral commissions facilitate cooperation in transboundary waters. There Communications and cooperation on the are, however, several relevant regional bodies. Ganges is currently undertaken through bilateral joint commissions. Despite discussions over The South Asian Association for Regional the years, there is no basinwide mechanism for Cooperation (SAARC) as it was originally intergovernmental communications or cooperation conceived was not mandated to address regional in the Ganges. Bilateral mechanisms, however, have water issues. In the context of climate change, been in place for decades and continue to evolve. SAARC has begun to consider some water issues. In the meantime SAARC has been instrumental in The Indo-Bangladesh Joint Rivers creating regional institutions mandated with disaster Commission (JRC) has been functioning since management and meteorological research. The 1972, following a joint declaration of the Prime SAARC Disaster Management Centre, established Ministers of Bangladesh and India. Its mandate is to in Delhi in 2006, focuses on training and exchange ensure effective joint efforts to maximize the benefits of good practices, and has a mandate to serve the from common river systems. It is headed by the water South Asian countries ‘by providing policy advice resource ministers of the two countries. and facilitating capacity building services including strategic learning, research, training, system The current institutional mechanism between India development and exchange of information for and Nepal is the Indo-Nepal Joint Committee effective disaster risk reduction and management.’38 on Water Resources (JCWR), which was formed The SAARC Meteorological Centre, established in by agreement between the Prime Ministers of Nepal Dhaka in 1995, promotes collective research in and India in 2000. In order to rationalize the meteorology and weather forecasting in the region.39 37 World Bank 2011. 38 SAARC Meteorological Research Centre 2011. 39 SAARC Meteorological Research Centre 2011. 27 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks The International Centre for Integrated facilitated work on the ‘South Asia Development Mountain Development (ICIMOD), established Triangle/Quadrilateral’ and related efforts that in Kathmandu in 1983, is a regional knowledge focused on developing analytical tools and improving development and learning center serving eight regional dialogue on the Ganges-Brahmaputra Basin. regional member countries of the Hindu Kush– Himalayas. ICIMOD aims to help mountain Today, the World Bank, in partnership with the people to understand changes in fragile mountain governments of Australia, Norway, and the United ecosystems, adapt to them, and make the most Kingdom, supports the South Asia Water of new opportunities, while addressing upstream– Initiative (SAWI). SAWI seeks to promote improved downstream issues. ICIMOD promotes transboundary water resources management within and among cooperation through partnership with regional partner the countries of the region, with an emphasis on institutions, facilitates the exchange of experience, transboundary cooperation and climate adaptation. and serves as a regional knowledge hub. It facilitates the Abu Dhabi Dialogue, a Track 2 forum launched in 2006 to enable a sustained dialogue of The Asian Disaster Preparedness Centre opinion makers and decision makers from the seven (ADPC) was established in Bangkok in 1986 at countries that share the rivers rising in the greater the recommendation of the United Nations office Himalayas (Afghanistan, Bangladesh, Bhutan, China, now known as UN Office for the Coordination of India, Nepal, and Pakistan); complemented by a Humanitarian Affairs (UN-OCHA) with the aim of knowledge forum of more than 50 regional research strengthening the national disaster risk management institutions and a small grants fund for collaborative systems in the region. In 1999 ADPC became an research. SAWI also supports knowledge independent entity, which is governed and guided development (this report is a product of SAWI) and by a board of trustees (21 members representing 15 innovative investments and actions that can enhance countries) and advised by a regional consultative regional capacity and promote cooperative. committee (32 members from 26 countries) and an advisory council (55 members from a wide range The International Union for Conservation of of agencies.) ADPC is active in developing and Nature (IUCN) recently launched the Ecosystems enhancing disaster risk management capacities, for Life: Bangladesh-India Initiative that uses a multi- frameworks and mechanisms, and facilitating stakeholder dialogue process to promote insights the dissemination and exchange of disaster risk across the three major rivers systems, the Ganges, management expertise, experience and information. Brahmaputra, and Meghna. There has also been a history of ‘Track 2’40 discussions on transboundary cooperation. Climate Context In the 1980s, nongovernmental groups in Nepal Climate has always been a challenge in (Institute for Integrated Development Studies), the basin. People have been living with both the India (Center for Policy Research), and Bangladesh positive and negative effects of water variability for (Bangladesh Unnayan Parishad) worked closely to centuries; these natural cycles of inundation have highlight the benefits of cooperation; researching, both beneficial and destructive aspects. On the publishing, and promoting improved regional beneficial side, short periods of inundation provide dialogue. In the mid-1990s, the World Bank soil moisture that typically increases production in 40 A ‘Track 2’ process is a nonformal process of engagement in which stakeholders such as academics, retired officials, opinion makers, and social activists engage in dialogue to further a particular agenda, resolve conflict, or build confidence. 28 Overview Box 2 Defining Floods and Droughts National institutions define floods and droughts based on hydrological information (i.e. the presence or lack of water), and typically measure rainfall or water levels of a particular area. On the local level, the comparison with purely hydrological flood or drought has little meaning. People use measures of floods that relate to their immediate surroundings: in a ‘normal’ year, flood waters would not reach the house, or would not surpass residents’ knees, whereas in an ‘extreme’ year, water levels would submerge their houses. Where the discrepancy between the two definitions of floods and droughts is most visible is in the distribution of relief aid. Relief and support from state and national governments is dependent primarily on the official definitions and not local definitions. Even when official droughts/floods are declared, the lag time between the actual drought/flood occurring and the declaration make it very difficult for the most vulnerable to cope. the winter (rabi) planting season. However, peak monsoonal climate of the Ganges Basin, many flows also cause more extensive and devastating key strategies are increasingly impractical. Flood floods and disrupt social life and economic activity. recession agriculture, for example, has been See Box 2 on the difficulties of defining floods adopted by societies worldwide to turn seasonal and droughts. flooding to their advantage. If an area was known to flood, communities would use it only The challenge grows with mounting for (supplemental) agriculture without building population and resource pressures. While infrastructure or housing that would be at high traditional societies have used a range of coping risk of inundation. The extraordinary population strategies to adapt to the extreme and unpredictable density of the Ganges Basin, however, has led to Figure 21 Climate Change Vulnerability Index, 2011 Climate Change Vulnerability Index 2011 Rank Country Rating 1 Bangladesh Extreme 2 India Extreme 3 Madagascar Extreme 4 Nepal Extreme 5 Mozambique Extreme Rank Country Rating 6 Philippines Extreme 7 Haiti Extreme 8 Afghanistan Extreme 9 Zimbabwe Extreme 10 Myanmar Extreme Legend Extreme risk High risk Medium risk Low risk Low Risk Low Risk Medium Risk Medium High Risk High Risk Extreme Risk Extreme No Data Source: Maplecroft (2011). 29 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks permanent habitation and commercial investments climate-vulnerable countries in the world (Figure in flood plains. Today, some 2 million people live 21). These rankings take into account both the within the embankments of the Kosi River,41 an area physical threats expected with climate change, and that in earlier generations was used only for flood the countries’ capacity to manage those threats. The recession agriculture. Ganges Basin could arguably be the most climate vulnerable basin in the world. The Ganges Basin today is one of the most climate vulnerable areas in the world. Melting The Ganges is a ‘hot spot’ for climate- glaciers, intensified monsoons and water-induced induced conflicts. Climate change can disasters, and sea level rise – all the ills of climate exacerbate existing environmental crises and change – are expected to manifest in the basin. The create new tensions. These dynamics can in turn countries of the basin have little capacity to deal lead to social destabilization and possibly conflict. with today’s weather and hydrological variability, Globally, conflicts related to degradation of fresh much less the intensification expected with climate water resources, decline in food production, change. increased disasters, and environmentally induced migration are anticipated. Within the Ganges, India The Maplecroft 2011 rankings of vulnerability to and Bangladesh are identified as hotspots, implying climate change placed the Ganges’ three main an increased risk for climate-induced conflicts riparians as the first, second and fourth most (Figure 22).42 Figure 22 Climate Conflict Constellations Climate-induced increase Environmentally-induced Hotspot in storm and flood disasters migration Climate-induced decline in Climate-induced degradation food production of freshwater resources Source: WBGU (2007). 41 Winrock International/ICIMOD 2010. 42 WBGU 2007 30 3. Analytical Framework Overall Framework 3. Social analysis through literature review, focus group discussions, and key informant interviews This report provides an integrated basinwide to understand the social impacts of and responses perspective of future development options in the to water variability. Ganges Basin. It aims to provide useful insights on critical basinwide implications of major options There are necessarily many constraints in for water infrastructure development and related undertaking such an ambitious study. Key constraints future scenarios of water use and climate. It does and limitations are described below. not provide economic, social, environmental, or technical feasibility analysis for individual projects, or First, much of the data used for analyses of this try to indicate which particular piece of infrastructure sort are either not collected or not accessible. For (e.g. a mega-dam) is better than another one, or how these infrastructure components should example, in India, there is no public access to critical be phased. hydrological information (especially flow data) to help calibrate the water simulation and economic The aim of the Ganges SBA is to begin to fill a optimization models. Substantial effort was required critical knowledge gap by building a nested suite to find suitable approximations for critical data of models and targeted analyses that can provide from the public domain and to resolve conflicting a comprehensive, interdisciplinary, and systemic information. Even for other basic information, the understanding of the Ganges Basin. Currently, team and its partners had to collate (and sometimes the team is not aware of any publicly available even computerize), analyze, and quality check knowledge base or full basin model for the Ganges. multiple datasets in order to slowly develop what is A series of commissioned studies and original now perhaps the most comprehensive set of relevant analyses were needed across a range of disciplines data for the analysis of the basin’s potential in a in order to ensure a converging picture of the basin regional context. dynamics. The three major components of this work included: Second, when this work was initiated, there was no easily accessible model of the entire Ganges Basin 1. Water systems modeling and analysis to examine of sufficient complexity to help answer the basin’s the dynamics of the Ganges Basin including: fundamental strategic questions. The team therefore surface water system, water balance, irrigation collaborated with some of the most capable use, water quality, climate change implications, institutions in the region, working closely with them floods and glacier melt. to develop a new generation of water systems’ 2. Economics modeling and analysis to explore modeling tools. economic tradeoffs, distribution of benefits from new development projects in the basin, and Finally, it would have been ideal for this work to economic benefits of additional low flows and have been carried out in a cooperative manner by flood mitigation strategies. empowered agencies of the riparian governments. 31 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks However, the Ganges is one of the few large demography, economy, etc. These data were used international basins in the world with no permanent to both create maps for this report and provide institutional mechanism that involves multiple inputs to the analytical work conducted. A detailed riparians. The work was undertaken in partnership literature, data, and web review was undertaken with regional experts and repeated consultations to provide useful information for this study. Key were held with regional stakeholders, and it is hoped existing research drawn upon in developing the that future research of this sort can be carried out by knowledge base includes a recent study by the Snowy a partnership of riparian countries. Mountain Engineering Corporation (SMEC, 2009) on groundwater management for the Ghagra-Gomti Despite these limitations, this report presents the best Basin. available evidence on the Ganges from a basinwide perspective. The knowledge base and models are Basin Systems Simulation Modeling. To better considered of sufficient certainty to inform evidence- understand systems linkages and to explore the based discussions around a set of core critical implications of a number of development and climate issues, and provide platform for ongoing dialogue scenarios in the basin, a MIKE BASIN simulation and further technical analyses. model was developed by the Institute for Water Modeling in Bangladesh along with associated Water Systems Modeling models such as a MIKE 11 hydrodynamic model and MIKE 21 salinity model (IWM, 2010). Figure The study takes a fresh, objective look at the 23 shows a schematic of the primary network challenges and opportunities in the Ganges representation used in both the basin simulation Basin today. It draws upon a rich history of work and economic optimization models. It indicates the on the Ganges, and presents significant original complexity of the hydrologic network of the Ganges research commissioned to develop a suitable Basin system and supports the conclusion that knowledge base and set of analytical tools to help modern basinwide modeling approaches are needed answer fundamental questions about the dynamics of to capture the interrelationships among development the water system. This new work helps us understand, options under consideration, and hence fully inform in a much more nuanced manner, options that have basin development decisions. been on the table for a long time, and points toward sustainable development paths that are important Basin Hydrological Model (Soil and Water in a regional context. Some of the new work Assessment Tool - SWAT). The INRM (Integrated conducted for this study includes: (1) development of Natural Resource Management Consultants) a knowledge base, (2) simulation modeling of basin consortium based in New Delhi (from the Indian systems, (3) a basin hydrological model, (4) a flood Institute of Technology IIT-Delhi and Texas A&M analyzer tool, and (5) a glacier melt analysis. University ) developed the SWAT model for this study (INRM, 2011). It was used to analyze the water Knowledge Base Development. A geographic balance, irrigation use, water quality, and climate information system (GIS) platform was developed change implications on hydrology in a more detailed drawing upon publicly available global, regional, spatial perspective. As Figure 24 indicates, the national, and subnational data on administrative SWAT model provided greater detail of specific units, climate, surface and ground water hydrology, catchments in the basin. The model was also used irrigation, hydropower, and other water uses, to examine the water quality implications of various wetlands, water quality, topography, soils, scenarios (Figure 25). 32 Figure 23 ‘Simplified’ Schematic of the Ganges Basin Water Systems and Economic Optimization Models INF2 0 9 _ 3 INF2 0 7 _ 5 INF2 0 9 _ 4 INF2 0 9 _ 3 3 INF2 0 7 _ 1 INF2 0 9UTTARKHAND _2 INF2 0 7 _ 5 INF2 0 9 _ 4 INF2 0 5 _ 4 INF2 0 7 _ 4 INF2 0 5 _ 3 Upper Arun INF1 0 0 _ 4 INF2 0 7 _ 1 INF2 0 9 _ 2 INF1 0 0 _ 1 INF2 0 5 _ 2 INF2 0 7 _ 3 INF2 0 5 _ 4 INF2 0 7 _ 4 INF2 0 5 _ 1 Upper Arun INF2 0 5 _ 5 NEPAL Tamur INF2 0 9 _ 3 INF2 0 7 _ 3 INF2 0 9 _ 3 INF2 0 5 _ 5 DAM209_6 Ya muna River DAM207_1 NEPAL Arun III Kaliganghaki I Tamur Saptakosi River Pan ch eswar d am DAM209_4 DAM209_3 F2 0 9 _ 4 INF2 0 9 _ 3 INF2 0 9 _ 4 Seti INF2 0 9 _ 4 DAM209_6 INF1 0 1 _ 1 DAM2 0 5 _ 1 DAM207_7 Arun DAM207_1 Arun III Kaliganghaki I INF2 0 7 _ 2 Saptakosi River Arun Marsyandi Trisuli Reservoir INF1 0 0 _ 3 DAM209_4 DAM209_3 9_2 II DAM207_5 DAM207_4 DAM207_6 Pu rn ag iri d am Seti 9_2 INF2 0 9 _ 4 Burhi Gandaki Sunkosi II DAM207_7 DAM209_2 Lower Arun DAM209_5 Lak h war Dam INF2 0 7 _ 2 Arun Marsyandi Trisuli Reservoir DAM2 0 5 _ 2 Upper DAM209_3 DAM207_5 DAM207_4 DAM207_6 Upper DAM209_3 9_2 DAM1 0 1 _ 1 Burhi Gandaki Sunkosi II DAM209_2 Lower Arun DAM209_5 Ban b h asa Head wo rk s River Dam Upper DAM209_3 INF2 0 9 _ 1 DAM2 0 5 _ 3 III INF1 0 0 _ 2 ap an i (Kamali) NEPAL NEPAL An d h i Kh o la Dam Tamur III HIMACHAL PRADESH NEPAL INF2 0 9 _ 5 Kaligandhaki DAM2 0 5 _ 8 Tamur Sap ta Gan d ak i Dam RiverRiver DAM2 0 7 _ 3 Ko si Hig Vy asi Dam h Dam Ch isap an i (Kamali) Dam INF2 0 9 _ 1 DAM209_6 DAM209_6 IT0 5 _ 1 An d h i Kh o la Dam DAM207_2 Ko tti Beh l Reserv o ir Arun INF2 0 9 _ 5 DAM209_6 INF2 0 5 _ 8 Kaligandhaki II III INF2 1 0 _ 1 DAM2 0 5 _ 8 Saptakosi NEPAL DAM2 0 7 _ 8 DAM1 DAM209_4 Sap ta Gan d ak i Dam Arun IRR2 0 5 _ 3 DAM2 0 9 _ 70 1 _ 2 Tamur DAM2 0 7 _ 3 Saptakosi DAM1 0 0 _ 6 Ko si Hig h Dam Arun DAM207_2 DAM209_4 INF2 0 8 _ 1 p er Gan UpINF2 0 9g_a6Can al East Gan g a Can al IRR2 0 5 _ 1 INF2 0 5 _ 6 INF2 0 5 _ 8 DAM2 0 7 _ 8 INF2 1 0 _ 1 Arun DAM209_6 INF2 0 7 _ 6 IT0 7 _ 1 IRR1 0 0 _ 1 IT0 0 _ 1 IRR2 0 5 _ 3 DAM2 0 9 _ 7 II IIII Arun INF1 0 1 _ 2 Kamala Dam IRR1 0 0 _ 2 INF2 0 8 _ 1 Saptakosi DAM209_4 Rap ti Dam INF2 0 9 _ 6 Mahakali Sunkosi BANGLADESH INF2 0 7 _ 6 Arun DAM209_2 Tamur DAM209_5 Lower DAM209_5 DAM2 0 9 _ 1 IT0 7 _ 1 Sunkosi IT0 9 _ 2 (Sarada) River Kamala Dam DAM209_2 F2 0 5 _ 7 DAM2 0 5 _ 9 IT0 5 _ 6 INF1 0 0 _ 5 Lower DAM209_5 Ku lek h an i Go mti riv er Rap ti Dam BANGLADESH IRR2 0 7 _ 1 IT0 9 _ 1 IT0 5 _ 3 INF2 0 5 _ 7 DAM2 0 9 _ 1 IT0 9 _ 2 DAM2 0 8 _ 1 GWR0 0 _ 1 IT0 3 _ 1 DAM2 0 5 _ 9 IT0 5 _ 6 Ku lek h an i DAM209_2 Lower DAM209_5 INF1 0 3 _ 1 IRR2 0 7 _ 1 IT0 9 _ 1 9_1 DAM2 0 8 _ 1 9 _ 1 INF2 Rap _5 0 9 ti Nep al INF2 0 9 _ 5 IRR2 0 9 _ 2 river Sunkosi river 0 8 _ 2 n a West Can al INF2Yamu 0 9 _ 1n a East Can al IRR2Yamu Mechi River o si Hig h Dam INF2 0 9 _ 5 Lu ck n o w City Su p p ly IRR2 0 5 _ 5 FL5 Rap ti Nep al IRR2 0 9 _ 2 river IRR1 0 1 _ 1 IRR1 0 1 _ 2 river 9o _si1 Hig h Dam INF2 1 0 _ 1 Mad h y a West Gan g a Mad h y a East Gan g a INF1 0 0 _ 6 INF2 0 8 _ 2 IRR2 0 9 _ 1 Mechi River Babai (Surya) DAM2 0 9 _ 7INF2 1 0 _ 1 INF2 0 INF2 9_5 10_1 WS1 0 3 _ 1 IRR2 0 5 _ 5 FL5 DAM209 _6 09_7 INF2IT0 059_ _76 IT0 7 _ 2 IRR1 0 0 _ 3 IRR1 0 0 _ 4 IT0 5 _ 2 Babai (Surya) 2si o Hig h Dam INF2 0 9 _ 6 Karnali (Ghagra) IT0 8 _ 1 IT0 1 _ 1 IT0 7 _ 2 mala _ 5 Dam DAM2 09_7 INF2 1 0 _ 1 IT0 5 _ 7 mala Dam BANGLADESH BANGLADESH IT0 0 _ 2 IT0 8 _ 1 M2 0 9 _ 1 IT0 9 _ 2 INF2 0 9 _ 6 BANGLADESH GWR1 0 1 _ 1 INF1 0 0 _ 7 IT0 5 _ 4 IT0 5 _ 5 M2 0 9 _ 1 IT0 9 _ 2 Western Gan d h ak FL1 3 GWR0 0 _ 2 mala Dam Ko si western can al IT0 9 _Ko si Eastern can al INF3 Sard a Sah _1 1 4ay ak GWR1 0 5 _ 7 IRR1 0 7 _ 2 Western Gan d h ak IT0 9 _ 3 River INF1 0 1 _ 3 BANGLADESH IRR1 0 9 _ 3 Ko si western can al INF3 1 4 _ 1 M2 0 9 _ 1 IT0 9 _ 2 IRR1 0 9 _ 4 IT1 0 _ 1 IRR1 0 5 _ 2 GWR1 0 5 _ 7 IRR1 0 7 _ 2 Ko si Eastern can al _2 IRR2 0 9 _ 2 GWR0 0 _ 3 IRR1 0 9 _ 3 IT1 0 _ 1 IRR2 0 9 _ 1 Can Hin d en R. Girija B IT0 5 _ 9 IRR1 0 9 _ 4 IRR2 09_2 EasternAg Ganrad ak al River River Mechi River Mechi IRR2 0 9 _ 1 Rap ti B INF1 1 0 _ 2 IT0 0 _ 3 Mechi IRR1 IRR1 0 7 _031 _ 3 FL7 INF3 1 3 _ 1 Rap ti B Eastern Gan d ak INF1 1 0 _ 2 Su ry a B IRR1 0 5 _ 6 INF3 1 3 _ 1 IRR2 0 9 _ 2 FL2 IRR1 0 5 _ 6 IRR1 0 7 _ 3 FL7 IRR2 0 9 _ 1 INF1 0 1 _ 4 GWR1 0 5 _ 2 Mechi IRR1 0 5 _ 4 FL4 Su ry a B FL6 IT0 1 _ 2 Lo wer Gan g a Can al IRR1 0 5 _ 4 FL4 FL6 Banganga River GWR1 0 1 _ 2 IRR1 0 0 _ 5 FL3 Kamala River INF1 0 5 _ 1 0 IT0 0 _ 4 UTTAR PRADESH Banganga River Kamala River IT0 9 _ 3 INF1 0 5 _ 1 0 i western can al IT0 9 _ 3 INF3 1 4 _ 1 INF3 1 4 _ 1 i1 0 5 _ 9 can astern western canalal IT0 5 Ko_ 8si Eastern can al INF3 1 4 _ 1 INF1 0 0 _ 8 IRR1 09 _3 Ko si Eastern can al INF1 0 5 _ 9 IT0 5 _ 8 R1 RR1 09 0_94_3 IRR1 IT1 00 _91_ 4 IT1 0 _ 1 IT1 0 _ 1 Kan r city Su p p ly (Bangladesh) i western can al IT0 9 _ 3 IRR1 0 9 _ 4 INF3 14p_u1 Ko si Eastern can al (Bangladesh) Mohananda River INF1 0 1 _ 5 WS1 0 0 _ 1 River RR1 0INF1 9_3 10_2 INF1 1 0 _ 2 IT0 1 _ 3 Mohananda River (India) River 05_11 FL7IRR1 0 9INF1 _ 4 1 0 _ 2 Delh i Water IT1Su0 _p1p ly INF3 1 3 _ 1 INF3 1 3 _ 1 IT0 0 _ 5 INF3 1 2 _ INF1 0 0 _ 9 1 (India) FL7 WS1 0 1 _ 1 INF3 1 3 _ 1 INF1 0 5 _ 1 1 INF3 1 2 _ 1 Jamuna River Gandhak River Upper Meghna Jamuna River Rapti River INF1 1 0 _ 2 INF1 0 0 _ 1 7 Gandhak River Upper Meghna Mohananda River Ag ra City Su p p ly Rapti River INF3 1 3 _ 1 INF1 0 0 _ 1 7 Mohananda River Bagmati River FL7 Bagmati River Kosi River Ghagara River WS1 0 1 _ 2 River Kosi River INF1 0 0 _ 1 4 BIHAR INF1 Gan 00 g es _10 e Barrag INF1 0 0 _ 1 1 INF1 0 0 _ 1 4 INF1 0 1 _ 9 INF1 0 1 _ 1 2 INF1 0 1 _ 1 8 INF1 0 0 _ 1 2 BIHAR Gan g es Barrag e INF1 0 0 _ 1 3 IT0 1 _ 4 (p lan n ed ) INF1 0 0 _ 1 3 (p lan n ed ) River River IT0 0 _ 1 9 River IT0 0 _ 1 6 IT0 IT0 0 _ 1 9 IT0 0 _ 1 6 Pa d _ 8 River 0ma River River IT0 0 _ 1 8 Pa d ma River IT0 0 _ 6 IT0 0 _ 1 8 (Bangladesh) (Bangladesh) IT0 0 _ 1 1 IT0 0 _ 1 2 IT0 0 _ 1 4 IT0 0 _ 1 5 FL8 IT0 0 _ 1 4 Meghna IT0 0 _ 1 3 IT0 0 _ 1 7 FL8 (Bangladesh) Ga ng es River INF1 0 1 _ 1 6 Ga ng es River IT0 0 _ 9 IT0 0 _ 1 0 IT0 0 _ 1 1 IT0 0 _ 1 2 IT0 0 _ 1 3 IT0 0 _ 1 5 IT0 0 _ 1 7 Mohananda River Mohananda Ga ng es River Ga ng es River River River River River IT0 0 _ 7 Meghna Mohananda IT0 1 _ 9 (India) (India) River River INF3 1 2 _ 1 INF3 1 2 _ 1 Farak k a IT0 1 _ 1 2 (India) Parwan Irrig atio n INF3 1 2 _ 1 Farak k a (Bangladesh) Jamuna Jamuna Meghna River _16 GWR1 0 1 _ 1 6 Upper Meghna Upper INF1 0_15 INF1 0 0IT0 1_5 IT0 1 _ 1 1 INF1 0 0 _ 1 6 Mohananda IRR1 01_ 04 INF1 0 0 _ 1 5 Jamuna River River INF1 0 0 _ 1 7 INF1 0 0 _ 1 7 River Mohananda River Mohananda Mu sak h an d Dam Upper IT0 1 _ 1 4 (India) INF1 0 0 _ 1 7 INF3 1 2 _ 1 IRR1 0 1 _ 1 2 Mohananda Kosi DAM1 0 4 _ 2 River IT1 1 _ 4 IT0 1 _ 1 6 River IT1 1 _ 4 Jamuna Kosi Upper INF1 0 0 _ 1 7 Gan g es Barrag e GWR1 0 1 _ 6GanINF1 g es Barrag 11_1 e IRR1 0 1 _ 1 0 IT0 1 _ 1 5 Mohananda Gan g es Barrag e IRR1 0 1 _ 1 1 Ran g wan Dam INF1 1 1 _ 1 icip al area Ad h u ara Mu n icip al area Lower Meghna Lower Meghna (p lan n ed ) (p lan n ed ) Kosi River IT0 0 _ 1 9 IT0 0 _ 1 9 (p lan n ed ) GWR1 0 1 _ 1 4 DAM1 0 1 _ 1 1 GWR1 0 2 _ 2 _1 IT0 RAJASTHAN 0 _ 1 6 IT0 0_19 IT0 6 _ 1Gan g es Barrag e Ma yura k shi River IT0 4 _ 1 WS1 0 4 _ 1 Ma yura k shi River Pa 0ma d IT0 0 _ 1 6 River IT0 1 _ 6 Pa d ma Massan River jo re Dam INF1 0 1 _ 1 1 IRR3 0 0 _ 6 Massan jo re Dam IRR3 0 0 _ 6 IT0 0 _ 1 4 IT0 0 Pa_1 d8ma River IT0 0 _ 1 8 IT0 2 _ 2 IT0 FL8 IT0 0_15 FL8 IT0 0 _ 1 7 (p lan n ed ) IT0DAM1 IT0 0 _ 1 8 Maith an DAM1 1 1 _ 1 IT00 0__1 154 Ga ng IT0es0River _15 FL8 IT0 0 _ 1 Ga9 ng es River Maith an 0 _0 INF1 11 7_1 81 _ 1 Dau d h an Dam GaDhngaoes lpIT0 0 _ 1 6 River IT0 0 ma Pa d _17 River n icip al area u r muDAM1 11_2 DAM1 0 1 _ 1 0 IRR1 0 2 _ 2 DAM1 1 1 _ 2 IT0Farak 0_1k 4a Farak k a IT0 0 _ 1 8 IT0 Farak 0_15 k a FL8 INF1 11 _2 WS1 0 1 _ 3 Nau g arh Dam INF1 1 1 _ 2 Baghirathi / Hoogly River IT0 0 _ 1 7 Ken River INF1 0 2 _ 2 Baghirathi / Hoogly River INF1 0 0 _ 1 6 Ga ng es River INF1 0 0 _ 1 6 DAM1 0 4 _ 1 GWR1 0 6 _ 1 INF1 0 1 _ 1 7 IT1 1 _ 2 IT1 1 _ 3 Meghna GWR1 Farak0 6 _ 1k a IT1 1 _ 2 INF1 0 1 _ 1 0 IT1 1 _ 3 END2 END2 River River IT1 1 _ 4 IT1 1 _ 4 Meghna INF1 0 0 _ 1 6 INF1 1 1 _ 3 Keo lari INF1 0 4 _ 1 INF1 1 1 _ 3 INF1 1 1 _ 1 IT1 1 _ 4 IT0 1 _ 7 GWR1 0 1 _ 1 0 END3 INF1 1 1 _ 1 _10 IRR1 0 1 _ 7 END3 Da mo d a r River Meghna Lower Meghna Lower Pan ch et Resev o ir Da mo IT0 d a r1River IT0 2 _ 1 Ka rma na sa Pan ch et Resev o ir River River Lower Ma yura k shi River IT1 1 _ 4 Ch amb al left b an k Ma yura k shi River e Dam Massan jo re Dam Ma yura k shi So n River Ch amb al rig h t b an k So n left So n Rig h t Ban k DAM1 1 1 _ 3 Kan g sh ab ati INF1 1 1 _ 1 So n left IRR3 DAM1 IRR3 g sh ab ati River / / Rig h t Ban k IRR1 0 1 _5 00_6 GWR1 1 10_1 3_ 7 0 0 _ 6 Kan INF1 0 1 _ 1 5 Massan jo re Dam IRR3 00_6 IRR1 0 6 _ 1 IRR1 0 6 _ 2 River Lower DAM1 1 1 _ 1 IRR1 0 6 _ 2 IRR1 0 1 _ 6 IT0 6 _ 1 DAM1 1 1 _ 4 aith 1 _an T0 61_ 1 IRR1 0 6 _ 1 Ma yura k shi River DAM1 1 1 _ 4 IT1 1 _ 1 IT1 1 _ 1 DAM1 1 1 _ 1 Ko ta Dam INF1 0 6 _ 3 / ith an Massan jo re Dam IT0 1 _ 1 3 To ns River IT0 6 _ 3 INF1 1 1 _ 4 111_2 IT0 6 _ 3 INF1 1 1 _ 4 IRR3 0 0 _ 6 DAM1 0 1 _ 5 GWR1 0 1 _ 1 3 River River 111_2 DAM1 1 1 _ 1 Ha ld ia River Baghirathi / Hoogly River Baghirathi Hoogly ith an Ha ld ia River Baghirathi Hoogly IT0 6 _ 2 111_2 IT1 IT1 1 _12_ 3 IT1 1 _ 3 IT1 1 _ 2 IT1 1 _ 3 END2 INF1 0 1 _ 7 END2 INF1 0 2 _ 1 IRR1 0 6 _ 3 Baghirathi Hoogly END2 Ran ap ratap sag ar JHARKHAND JHARKHAND GWR1 01_8 END3 END3 GWR1 0 6 _ 2 Da mo et Resev d a r River o ir IT1 1 _ 2 Da mo d a r River IT1 1 _ 3 END2 DAM1 0 1 _ 4 END3 WEST BENG AL et Resev o ir Da mo d a r River IT0 1 _ 8 BENG WEST AL INF1 0 1 _ 1 4 bM1 ati 1 1 _ 3 Kan g sh ab ati END3 END1 M1 1 1 _ 3 Kan g sh ab atiDa mo d a r River END1 INF1 0 6 _ 4 et _4 Resev o ir DAM1 1_4 Gan d h isag ar Dam INF1 0 1 _ 1 3 MADHYA PRADESH DAM1 IT1 11 11 _ 1_4 1_1 06_4 IT1INF1 M1 1 1 _ 3 Kan g sh ab ati IT1 1 _ 1 DAM1 0 1 _ 3 INF1 0 6 _ 2 North Kael River INF1 0 6 _ 2 IRR1 0 1 _ 8 INF1 0 6 _ 1 North Kael River Ha ld ia River DAM1 1 1 _ 4Ha ld ia River IT1 1 _ 1 Ha ld ia River Ha ld ia River INF1 0 1 _ 6 CHHATTISGARH ISGARH BENGAL WEST BENGAL Pard k h WEST BENGAL Cha mb a l River IRR1 0 1 _ 9 END1 END1 Riv er Dam (Ex istin g ) END1 WEST BENGAL Riv er Dam (Ex istin g ) END1 Irrig atio n Irrig atio n Div ersio n Div ersio n In tern atio n al In tern atio n al Bo u n d ary Bo u n d ary Dam (Plan n ed ) Dam (Plan n ed ) State Bo u n d ary State Bo u n d ary Riv er River Riv er Dam (Ex istin g ) Dam (Ex istin g ) Dam (Existing) State Boundary Riv er Dam (Ex istin g ) Riv er Irrig atio n Dam atio n Irrig (Ex istin g ) Div ersio n Div ersio n Irrig atio n Diversion Div ersio n Irrigation In tern atio n al In tern Irrig atio atio n n al Div ersio n Bo u n d ary In Botern u n atio d aryn al Dam (Plan n ed ) Dam (Plan n ed ) Bo u n d ary Dam (Planned) Dam (Plan n ed ) In tern atio n al State Bo u n d ary State Bo und Boaryu n d ary International Boundary State Bo u n d ary Dam (Plan n ed ) State Bo u n d ary Source: IWM (2010). 33 ANALYTICAL FRAMEWORK Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 24 Catchments in the MIKE BASIN Model (left) and SWAT Model (right) Basins Ocean SWAT Sub-basin Betwa Ganga Hoogly Mahananda Chambal Ghaghra Ken Sindh Gandak Gomati Kosi Son Tons Yamuna Source: INRM (2011). Figure 25 Water Quality Modeling in SWAT Non-Monsoon Months Monsoon Months BOD Load (ppm) 0.0 Average Rainfall Year 0.0 - 0.5 0.5 - 1.0 1.0 - 2.0 2.0 - 3.0 > 3.0 Source: INRM (2011). 34 ANALYTICAL FRAMEWORK Flood Analyzer Tool. This model was developed analysis. It is important to note that these scenarios by RMSI, Pvt. Ltd., New Delhi, to better understand were not chosen based on their likelihood, rather the history and nature of floods in the Basin and the they were chosen to help represent the range of losses from various flood scenarios (Figure 26). possible future developments and to provide insights regarding some fundamental questions about the Glacier Melt Analysis. This This analysis, carried dynamics of development in the basin. out by Professor (emeritus) Don Alford, Professor Richard Armstrong, and Dr. Adina Racovitaneu, The scenarios in Table 4 explore the role of estimated glacial melt contribution and climate additional infrastructure in providing systemwide change-induced glacier melt enhancement in the benefits in the Ganges Basin. Some of the key Ganges Basin. storage scenarios considered in the systems simulation modeling are summarized in Table 4 In addition, the authors of this study undertook a and Figure 27. These results also present insights number of further analyses relating to knowledge- regarding the role climate change may play in base development, climate change, and use of the infrastructure investment decisions. new tools described above. Water System Model Criteria and Indicators Water Systems Modeling Scenarios Impacts of the various development options A number of scenarios for the future of were examined at particular locations. In any the Ganges Basin were considered in this system model, just as it is possible to analyze many Figure 26 Flood Risk Management Analytical Framework RMSI Flood Risk Modeling Historical Weather • Rainfall • Temperature • Solar Radiation • Relative Humidity • Wind Speed GIS Input Bio Physical • River Network Distributed Hydrological Model • Soil • Catchment Properties • SWAT • Land use • Roughness • DEM • Reservoir Simulation of flows • Discharge • Stages Identification of Exposure at Risk • Loss of life • Livestock • Infrastructure • Agricultural Assets Vulnerability Function • Stage Vs Damage • Rainfall Vs Damage Flood Loss Assessment • District level • State level Source: RMSI (2011). 35 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks scenarios, it is also possible to examine an extensive flow data upstream at the proposed Chisapani43 set of output results (e.g., flows at various sites and dam site in Nepal, and also at Hardinge Bridge time periods). To keep the study manageable, results near the end of the system in Bangladesh. Additional were examined at particular locations of interest. In data (especially in India) would enable improved Figure 28, the yellow circles indicate where flows calibration of the models. However, this analysis were analyzed for the potential impact of major should be adequate for the scale of the river system upstream dam development. and the level of the strategic questions posed. The water systems modeling work focused The model is not always able to accurately on a cluster of key biophysical criteria and characterize the flood peaks, possibly due to indicators (Table 5), which present the ‘backbone’ reliance on sparse rainfall data (as many of the of new information in this study. Complemented by remote catchments of the rugged Himalaya have socioeconomic information, they form a picture of neither meteorological stations nor gauges). Hence, alternative futures in the Ganges. the model does not fully reflect the heterogeneous nature of variability in the many mountain catchments and subcatchments in the system. This Water Systems Model Calibration and Testing issue could be partially addressed by improved Models are a simplification of reality. Despite many monitoring and integration of increasingly reliable data challenges, the models on which the insights modern satellite information into the available presented in this report are based have been hydrometeorological data systems. reasonably calibrated and tested (IWM, 2010). Good flow calibration results were obtained by Simulated flows in India could not be calibrated or IWM’s MIKE BASIN model for the available observed validated due to the lack of publicly available daily Table 4 Water System Modeling Scenarios Scenaio Year Infrastructure April 1998- A Current Baseline Existing June 2008 B Business as Usual Gorai River Restoration C (B+Gorai RRP) D (C+Ganges Barrage) Ganges Barrage (and Gorai Restoration) E (B+Kosi) Kosi High Dam 2025 F (B+Mahakali) Mahakali Dam G (B+25 GW installed) Mahakali, Kosi and Chisapani, + KaliGand I&II+Dams H (G+other major storages in Nepal) All major Storages in Nepal built I (B+Br-Gan .link) Brahmaputra-Ganges link in Bgd J1: Existing J ([B; H] Climate Change 2050 J2: All major storages Source: IWM (2010). 43 The Chisapani Dam site on the Karnali River is shown here for illustrative purposes. Similar results were achieved for all other major Nepali basins. 36 Figure 27 (a) Schematic Representation of Storage Options Impact Analysis Points Barrage (Planned) State Boundary Scenario C Scenario E Dam (Planned) River International Boundary Scenario D Scenario F 37 ANALYTICAL FRAMEWORK 38 Figure 27 (b) Schematic Representation of Storage Options Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Impact Analysis Points Barrage (Planned) State Boundary Scenario G Scenario I Dam (Planned) River International Boundary Scenario H Source: IWM (2010). Note: Scenario C considers dredging in the Gorai River, Scenario D considers the Ganges Barrage in Bangladesh, Scenario E considers the Kosi Dam, Scenario F considers the Pancheswar Dam, Scenario G considers large dams with 19gigawatt total capacity, Scenario H considers all planned dams in Nepal, Scenario I considers the Jamuna-Ganges link in Bangladesh, and Scenario J considers climate change scenarios. Figure 28 Major Impact Locations for the Water Systems Model CHINA Seti 1 a Ba nd gh Seti 6 Karnali-1B na ira ti Bh lka Arun Kaligandhaki i Lower Arun III Seti Marsyandi Trisuli Burhi Gandaki A er Sunkosi II Tamur i NEPAL Pancheswar Kosi High r Kaligandhaki ii Dam UTTARAKHAND Bheri Andhi Sapta Gandhaki R ive Karnali Purnagiri Chisapani 4 Khola Dam da an h an Bangladesh Mo Mechi Gomti Girija Gandak HARYANA Chatara Babai Barrage Barrage Kotu a ng Mahakali(Sarada) ga m Yamuna Ra ki Lower Sarda Deo Barrage Kosi Kamala Bagmati Gandak Mohananda (Bangladesh) Rapti Jamuna Ganges Ghagara Mohananda (India) Upper Meghna BIHAR Ganges Hardinge Allahabad Barrage Bridge Padma Ganges Patna Ganges Farakka Baruria Ilshaghat UTTAR PRADESH Hisna Arial Khan Gorai Chandara Mayurakshi Matabangha Sind Maithan Lower Meghna Damodar Baghirathi/Hoogly Ken Karmanasa JHARKHAND Haldia Betwa Tons Chambal Rih Son WEST BENGAL and North Koel Madhya Pradesh CHHATTISGARH Impact Analysis Points Barrage (Planned) State Boundary Dam (Planned) River International Boundary Source: IWM (2010). 39 ANALYTICAL FRAMEWORK Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Table 5 Key Criteria and Indicators for the Water Systems Models Criteria Indicator Hydrology Flows in major rivers (monthly hydrographs, by year and average) Descriptive statistics (average, changes) Schematics Flooded areas (in Bangladesh) Energy Basin hydropower production (by site and total) Environment Salinity intrusion (maps, values at key locations) Key pollution levels at key locations (e.g., BOD, DO) Navigation Navigability of key reaches Demands Key water demands for urban and irrigation (annual and monthly) flow datasets; however, they seem to be consistent data from Naryanghat on the Gandak River, with other proxy data (e.g. results of other models Chisapani on the Karnali (Ghaghara) River, Banga such as the SWAT model, monthly averages from the near Belgaon on the West Seti River, Jamu on the literature) and the good calibration obtained further Bheri River, and Chatara Kotu on the Kosi River in downstream (e.g. as shown at the Hardinge Bridge Nepal; as well as at Hardinge Bridge on the Ganges in Bangladesh) also provides a certain degree of in Bangladesh. The Nash-Sutcliffe coefficients44 confidence in the accuracy of the models. for calibration and validation of daily flows are greater than 0.74 and 0.73, respectively, in all The other models used were also calibrated the calibration points of the model. The simulated successfully. For example, the MIKE 11 monthly volumes in the monsoon consistently show hydrodynamic model, developed over many years good agreement for calibration years; they are at the IWM, was able to reproduce observed generally within 10 percent and always within 14 data within Bangladesh. The MIKE 21 advection- percent of observed values. The simulated monthly dispersion salinity model, developed in 2008 at volumes for low-flow conditions (excluding Hardinge IWM, also shows reasonable calibration. The SWAT Bridge where there are inadequate observed values models show very good calibration as well for for the dry season) are within 35 percent of observed the catchments modeled. The calibration of these values. Discharge data of stations situated within models is illustrated in Figures 29-33. the Ganges Basin are essential to increase the calibration points and thereby improve performance Figure 29 shows good calibration of the MIKE of the model. Overall, the model can be considered BASIN Model at the Chisapani Dam site in Nepal’s adequate and acceptable for making relative Karnali Basin. The basin simulations show good comparisons at the basin level. agreement based on daily, monthly, and annual comparisons with observed data. Calibration of Figure 30 shows similarly good model fits for the the basin model was done using daily discharge MIKE BASIN model near the end of the river system, 44 Nash-Sutcliffe efficiency coefficients (R squared) are model accuracy statistics used to assess the predictive power of hydrological models. A coefficient of 1 means a perfect fit between modeled discharge and observed data. 40 ANALYTICAL FRAMEWORK Figure 29 Calibration and Validation of the MIKE BASIN Model (Karnali Basin in Nepal) 14000 – Flow Calibration Nash-Sutcliffe coefficient = 0.79 14000 – Flow Validation Nash-Sutcliffe coefficient = 0.73 12000 – 12000 – 10000 – 10000 – Cumecs 8000 – Cumecs 8000 – 6000 – 6000 – 4000 – 4000 – 2000 – 2000 – 0– 0– l l l l l l l l l l l l l l l l 1/01/1998 20/07/1998 5/02/1999 24/08/1999 11/03/2000 27/09/2000 15/04/2001 1/11/2011 20/05/2002 6/12/2002 1/01/2003 20/07/2003 5/02/2004 23/06/2004 11/03/2005 27/09/2005 15/04/2006 1/11/2006 Simulated Observed Simulated Observed 100% – 14000 – 12000 – 80% – Average Daily Flow (cumecs) Exceedance Probability 10000 – 60% – 8000 – 40% – 6000 – 4000 – 20% – 2000 – 0% – 0– 1000 – 2000 – 3000 – 4000 – 5000 – 6000 – 7000 – 8000 – 9000 – 10000 – 11000 – 12000 – 13000 – 14000 – 15000 – 16000 – 17000 – Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Graph shows minimum, maximum, Monthly Volume (MCM/month) 0.05 percentile and 0.95 percentile values Observed Calibration Validation Within 90% limit Outside 90% limit Within 90% limit Source: IWM (2010). Simulation Observed Figure 30 Calibration and Validation of the MIKE BASIN Model at Hardinge Bridge in Bangladesh 90000 – 90000 – Flow Calibration Nash-Sutcliffe coefficient = 0.89 Flow Validation Nash-Sutcliffe coefficient = 0.85 80000 – 80000 – 70000 – 70000 – 60000 – 60000 – Cumecs 50000 – 50000 – Cumecs 40000 – 40000 – 30000 – 30000 – 20000 – 20000 – 10000 – 10000 – 0– 0– l l l l l l l l l l l l l l l l 1/01/1998 20/07/1998 5/02/1999 24/08/1999 11/03/2000 27/09/2000 15/04/2001 1/11/2011 20/05/2002 6/12/2002 1/01/2003 20/07/2003 5/02/2004 23/08/2004 11/03/2005 27/09/2005 15/04/2006 1/11/2006 Simulated Observed Simulated Observed 100% – 70000 – Average Daily Flow (cumecs) 60000 – 80% – Exceedance Probability 50000 – 60% – 40000 – 40% – 30000 – 20% – 20000 – 10000 – 0% – 8000 – 16000 – 24000 – 32000 – 40000 – 48000 – 56000 – 64000 – 72000 – 80000 – 88000 – 96000 – 104000 – 112000 – 120000 – 128000 – 136000 – 0– l l l l l l l l l l l l Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Monthly Volume (MCM/month) Observed Calibration Validation Within 90% limit Outside 90% limit Within 90% limit Simulation Observed Source: IWM (2010). 41 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks measured on the Ganges River at Hardinge Bridge Although this model focuses exclusively on these in Bangladesh. economic values, it does not suggest that these are the only values to be considered in the development Figure 31 shows excellent calibration of the MIKE of multipurpose infrastructure in the basin. The 11 hydrodynamic model in Bangladesh, measured Ganges is a river of enormous cultural, religious, at Hardinge Bridge in Bangladesh. and social significance, and these types of values also must be a central consideration. Ecosystem Acceptable calibration of the MIKE 21 salinity sustainability, recreation and tourism, navigation, model, measured at Khulna on the Pussur River in municipal and industrial water supplies, and equity Bangladesh, is shown in Figure 32. concerns within and across borders should all be factors in development decisions. Economics is just Economic Optimization Modeling one important part of the decision calculus. The Ganges economic optimization model attempts to maximize total annual economic benefits by The model is formulated as an annual, nonlinear, varying releases of water from a set of assumed constrained-optimization problem with a monthly infrastructure facilities. The total annual economic time step. The model determines the annual pattern benefits are the sum of the economic value of of water allocations that maximize the systemwide four components: (1) hydropower production from economic benefits from hydropower, agriculture, new and existing dams; (2) irrigation water for flood reduction, and downstream low flows. It the cultivation of agricultural crops; (3) reducing calculates the economic benefits by water use and flood damages; and (4) incremental low flows to by country. Minimum flows in specific upstream Bangladesh above the minimum legally required at reaches of the river and at the Farakka Barrage Farakka Barrage. are imposed in the model as constraints on river Figure 31 Calibration of the MIKE 11 Hydrodynamic Model at Hardinge Bridge in Bangladesh 80000 75000 70000 65000 60000 55000 50000 45000 40000 35000 30000 25000 20000 15000 10000 5000 0 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Simulated Observed Nash-Sutcliffe Coefficient = 0.94 Source: IWM (2010). 42 ANALYTICAL FRAMEWORK Figure 32 MIKE 21 Salinity Model: Modeled River System of the South West Khulna Legend: International Boundary BWDB Routine Station Model Boundary Water Level Station Schematized River Water Level and Discharge Catchment Boundary Rainfall Station 8 0 8 16 Kilometers Name of the Catchment Area Rainfall and Evaporation Ground Water Well Bangladesh Transverse Mercator Projection [IT214] D:\P0014\P5482s_av\Avdata\Aprfile\Av_0305\0305_av_6regions.apr [*KAR* 27 May, 2007] Layout: SW-A3 Source: IWM (2010). 43 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 33 MIKE 21 Salinity Model: Comparison of Simulated and Measured Salinity in the Pussur River Khulna-Simulated [kg/m^3] Khulna-Measured [kg/m^3] 20 18 16 14 12 Salinity (kg/m3) 10 8 6 4 2 0 January February March April May June July August 2007 2007 2007 2007 2007 2007 2007 2007 Source: IWM (2010). flow. In the analyses presented here, for example, are in Nepal, with the exception of the proposed upstream minimum flows must be sufficient to satisfy Pancheshwar Dam site on the Mahakali River, which all municipal demands, and downstream flows must is a border river shared by India and Nepal.45 Most at least be in accordance with the minimum flow of these reservoir nodes allow storage of inflows specified in the Ganges Treaty between India up to reservoir capacity, beyond which flows spill and Bangladesh. downstream (three of these new dams are run-of- the-river hydropower projects without water storage). The economic optimization model schematic Reservoir releases determine hydropower production (Figure 23) shows how the model characterizes and the amount of water available for downstream the Ganges system as a network of nodes and irrigation. links. There are five basic types of nodes: reservoirs, irrigation withdrawals, flood outflows, flood returns, There are 34 irrigation nodes in the optimization and intermediate nodes. The model includes 29 model, some of which, in reality, correspond to major existing storage reservoirs (all but one of very large command areas served by irrigation which are in India), plus 23 potential new dams. All canals. Some of these command areas currently of these new dams and the reservoirs behind them are only partially irrigated with surface water due 45 The Mahakali River runs north to south, with the right (western) bank in Indian territory and the left (eastern) bank in Nepal. The international border runs down the center of the river so half the Pancheshwar Dam and reservoir would be in each country. 44 ANALYTICAL FRAMEWORK to constraints on water delivery during the low- system); confluence (where multiple rivers meet); and flow period. At these nodes, the model removes distribution (where a river splits). In total, 77 of the water from the river system and partitions it into model nodes receive inflows from local catchments. four components. The first portion of this water is used to satisfy irrigation water demands for crops The mathematical model’s objective function is grown in the command areas (the amount of water expressed The mathematicalas: model’s objective function is expressed as: required in different areas is estimated based on crop water requirements obtained from the (1) United Nations Food and Agriculture Organization (FAO) crop water model, CROPWAT). The second where: where: model’s objective function is expressed as: The mathematical component accounts for losses to nonproductive evapotranspiration from canals and fields; The ourmathematical model’s Z total = total objective function(in economic benefits economic benefits is millions (in expressed millions ofof as: US$); US$); (1) analysis assumes this portion to be equal The 60 tomathematical model’s h objective economic function value is expressed ofhydropower hydropower as: (US$/kW-hr); where: p = economic value of (US$/kW-hr); (1) percent of the water actually used by crops (the first component), or 30 percent of the The water diverted annual hydropower generated in project at node k mathematical where: Z model’s = total objective = Annual economic function hydropower benefits is (inexpressed generated millions of as: US$);in project at (1) node k (in GW-hr/yr); (in GW-hr/yr); to irrigation areas. The third portion of diversions – 20 percent overall, or 40 percentThe mathematical Z model’s where: of the crop = h p total = objective irr economic economic p economic function =benefits economic value of (in is expressed value millions value hydropower as: water ofirrigation of irrigation of US$); (US$/kW-hr); water (1)(US$/m3); (US$/m3); water requirement – is assumed to flow back into volume of irrigation water delivered to area j, in The flows. mathematical where: Z p model’s h = total objective economic function benefits is millions (in expressed as: of US$); (1) the Ganges system via return Finally, the = economic= Annualvalue =of hydropower volume hydropower state/country m(US$/kW-hr); irrigation of generated water in project (in millions delivered ofat 3 to k ); area mnode j, in state/country m (in million (in GW-hr/yr); model allows additionalThe mathematical diversion where: of water h into objective model’s function is expressed as: Z = economic =ptotal economic= irr p Annual l of = value benefits hydropower economic p economic hydropower (in = millions ofof generated value economic value of (US$/kW-hr); US$); irrigation value inof lowflows flows project water low at(1) node (US$/m3); (US$/m (US$/mk (in3); 3 ); GW-hr/yr); groundwater recharge when the canal capacity is volume of low flows to Bangladesh during the lean (1) not fully utilized. This recharge Z water where: h is not p = total lost economic irr to p = Annual the benefits (in hydropower millions of generatedUS$); in project at node = economic =value ofvolume hydropower (US$/kW-hr); tokarea(in GW-hr/yr); 3 economic = value of = of seasonirrigation irrigation volume (January of water water low – flows(US$/m3); May), delivered to above Bangladesh the inFarakka state/country j,during the leantreatym (in millions season (Januaryof m ); – May) system; the model The addsmathematical it to storage model’s objective function is expressed in groundwater minimum as: millions (inmillions ofofmm ); ); 3 where:ph minimum (in 3 reservoirs beneath each irrigation Z node. = total Thisvalue = economic irr =pAnnual economic stored = of hydropower economic benefits hydropower = p (in l volume = value millions of economic of generated (US$/kW-hr); irrigation of irrigationUS$); in valuewater ofwater project low at(US$/m3); delivered flowsnode to k (US$/m (in area 3 j, in state/country m (in millions of m3); GW-hr/yr); ); channel capacity at economic cost of exceeding groundwaterThe canmathematical model’s then be pumped Z objective (at a cost)function and is expressed as: = total economic US$); k, in state/country m (in millions of US$); benefits (in millions ofnode (1) p = Annual hydropower generated in project at node k (in3 GW-hr/yr); h irr l =of 3 The mathematical used throughout the year to model’s p help objective = economic meet function value irrigation = economic p volume = is expressed hydropower value economicof irrigation ofvolume irrigation as: water (US$/kW-hr); water delivered (US$/m3); to area ); j, during in state/country m (in millions of m ); where: h = value of costof low low flows of flows pumping (US$/m (1)to Bangladesh recharged the lean season groundwater (US$/m (January 3 ); and– May), above th water demands when surface p =flows economic irr insufficient. arevalue hydropower ofvalue (US$/kW-hr); minimum (in millions 3 of m ); p = Annual= economic = l hydropower pvolume of of irrigation generated water water inof volume project (US$/m3); at of node recharged groundwater k (in3jGW-hr/yr); mpumped toofarea 3 j, The water balance for groundwater reservoirs = only=irrigation economic volume value of low delivered low flows flows (1) to to area (US$/m Bangladesh , in ); state/country during (in millions the lean season (January m – ); above the Fara May), where:Z = total economic benefits (in millions of US$); in state/country 3 m (in millions of m ). 3 incorporates flows out of the modeled irr = Annual surface hydropower minimum generated in(in millions project tom of at node ); k (in GW-hr/yr); 3 p = volume of =irrigation water delivered area3 j, in state/country m (in millions of m ); where: h p l = economic value = economic of irrigation valueof volume oflowwater low flows flows(US$/m3); to Bangladesh (US$/m ); during the lean season (January – May), above the Farakka water systemZand = does not include economic = irr ptotal economic benefitsrecharge value of hydropower (in from millions of US$); (US$/kW-hr); The model of m3 );uses a monthly time step t and 3 ‘green water’ (water p in=the stored economic l soil) value or fromof minimum irrigation local (in water millions (US$/m3); 3 p Z h = total economic benefits (in millions = = volume economic of irrigation = volume valueUS$); of of of waterlow determines flows delivered low flows to Bangladesh (US$/mto area); the, in value jduring of the state/country the lean mdecision season millionsvariables (in(January of m ); above the Farakka treaty – May), precipitationpand infiltration. = economic= Annual value hydropower of hydropower generated (US$/kW-hr); in project thatat node 3yield k (in the GW-hr/yr); highest outcome of the objective 3 minimumwater = volume of irrigation (in millions delivered of mto );area j, in state/country m (in millions of m ); p h = economic irr l p of hydropower value = volume = economic value of low (US$/kW-hr); flows to of low flows function Bangladesh 3 during the lean season (January – May), above the Farakka treaty (US$/m ); Z. This model-determined pattern of water There are also eight =pAnnual = leconomic flood hydropower outflow value of irrigation generated nodes. minimum in project Seven (in water millions at (US$/m3); of node 3 k (in GW-hr/yr); ); 3 mreleases p = economic value of low flows (US$/m ); and allocations to water users is subject are located on the irr = northern Annual hydropower Ganges=generated volume tributaries of inlow flowsat project tonode Bangladeshk (in GW-hr/yr); during to constraints the lean season on flow (January – May), continuity in 3 the above river, the Farakka treaty water p = economic valueof = volume irrigationwater ofirrigation waterdelivered (US$/m3); 3 to area j, in state/country m (in millions of m ); (Yamuna, Upper irr Ganga, Ghagara, minimum Rapti, (in Gandak, millions = volume of low flows to Bangladesh of m ); balanceduring the and lean partitioning season (January at –irrigation May), above nodes, the Farakka treaty p Bagmati, and = economic Kosi) value of irrigation water (US$/m3); l and one is on the main Ganges. 3 river channel capacity, low flow =pvolume of irrigation = economic minimum valuewater (in of millions delivered low flows m area to 3 of(US$/m ); j); , in state/country m (in millions of m ); 3 and municipal/ At these nodes, monthly flows in excess of natural industrial water requirements, 3 groundwater = volume of irrigation water delivered to area j, in state/country m (in millions of m ); river channel p lcapacities leave the river network and = economic valueof = volume oflow lowflows flowsto (US$/m Bangladesh 3 ); during and the surface lean season water storage (January capacity, – May), above the installed Farakka treaty cause flood l damage. A minimum fraction(in these of ofmillions river 3 3spills m );); hydropower capacity, irrigation water requirements, p = economic value of low flows (US$/m are then assumed=to return volume of lowto the flows river at the flood to Bangladesh during the and land availability. lean season (January – May), There aboveis also the a requirement Farakka treaty return nodes, which are minimum = volume located of low millions (in flows just to of downstream 3 m ); Bangladesh during the lean that season reservoirs all (January – May), above thethose (including Farakka for groundwater) treaty of the flood outflow nodes. The minimum (in millions of m ); other 3 intermediate end the year at the same level at which they began, nodes in the Ganges economic optimization model though optimal initial levels are determined by the account for inflow (i.e. where runoff enters the model. 45 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks In addition to these modeling efforts, a short study example diversions to Kolkata). Finally, a model user was commissioned on the economics of ‘hard’ can alter river channel capacities to reflect changes versus ‘soft’ flood mitigation strategies. in river geomorphology or the effects of enhanced embankment protection (assuming there are no There are a number of important limitations of breaches). the Ganges optimization model formulation. First, and perhaps most important, the model does not The consequences of constructing different sets incorporate hydrological uncertainty. It assumes that of upstream storage infrastructure are measured managers of the system know the pattern of inflows relative to a baseline that closely resembles current a year in advance and can adapt monthly operation conditions. It is not possible to precisely characterize ahead of time to optimize water allocations for the the present situation of Ganges water management year. Second, an annual model cannot describe the because the amount and precise pattern of consequences of a sequence of years of abnormally surface water withdrawals for different basin low or high flows. However, because there is little irrigation schemes in India are unknown. Instead, physical opportunity for over-year storage in the we estimated overall crop water requirements existing or potential infrastructure projects on in different irrigation schemes based on state- the Ganges, decisions on optimal releases from level data for the major crops in the existing mix, reservoirs will be made without consideration accounting for local climatic conditions and the of multiyear consequences. Third, estimates of differing cropping intensities in irrigated areas within annualized capital costs were made separately using Bangladesh, India, and Nepal.47 Thus, instead of old cost data inflated to present values. Capital costs constraining irrigation water withdrawals according of dam construction and new and expanded canals to existing surface water demands in the basin, the for irrigation were not directly included in the model model solves for the theoretical area of land that itself.46 Fourth, upstream water quality concerns should be irrigable given existing cropping patterns, have been included only through the minimum flow yields, market prices, and water use at the field constraints. Fifth, the Ganges economic optimization level according to the irrigation water partitioning model cannot precisely replicate the provisions of the parameters discussed above. Farakka Treaty (established in 1996) for allocation of water between India and Bangladesh. The economic optimization model was used to examine the impacts of four options for new Economics Optimization Model Data and infrastructure projects. The hydrological year used in Scenario Analysis the base case is the year 2000, for which the overall runoff into the Ganges was 502 billion cubic meters A user of this economic optimization model assumes (compared with an average of 508 billion cubic that a particular set of infrastructure projects is in meters over the 10-year period 1999–2008; range place; the model does not solve for the optimal set 460–545 billion cubic meters). None of the major of projects. A user can explore the consequences of river tributaries had exceptional hydrology in 2000. building different sets of new dam projects, and test the sensitivity of results to different hydrological flows The four options examined are: (using low, average, and high flow years). He/she can impose minimum flow restrictions or prioritize 1. Existing storage and flow regulation projects demands along critical stretches of the river (for (status quo, baseline case) 46 The purpose of these models is to look at basinwide dynamics, not to assess the costs and benefits of specific projects. Project-level analysis would require significant additional economic, social, and environmental analysis. 47 Japan International Cooperation Agency 1985; BBS (Bangladesh Bureau of Statistics) 2004; Indiastat 2005. 46 ANALYTICAL FRAMEWORK 2. Three proposed mega-dams in Nepal (Similar insights on the community-based flood management to Scenario G for the water systems models): strategies and the role of embankments in the Pancheshwar Dam on the Mahakali/Sarda River, basin. This analysis complements a literature review Chisapani Dam on the Karnali River, and the Kosi with new qualitative research, including focus High Dam on the Kosi River group discussions, semi-structured household-level 3. Only building smaller dams and run-of-the-river questionnaires, and open-ended interviews with local projects in Nepal, of which we include 20 (we and regional key informants and experts. In total, 68 include only the largest dams among many on a focus group discussions were conducted with men long list of possible projects) and women in communities facing a variety of water 4. All major proposed storage in Nepal built (similar management issues, including biodiversity loss, to Scenario H for the water systems models) salinity intrusion, water quality, floods, and droughts. Figure 34 shows the sites for the focus group Sensitivity analysis was conducted to explore the discussions. effects of several modeling assumptions on the results: (1) varying the relative economic value of low The key challenge was that the diversity of flows to the delta; (2) varying the economic value populations in the Ganges Basin makes it difficult of irrigation water; and (3) testing the effects of low, to ascertain impacts that can be generalized for the average, and high years of flow on both physical entire basin. The social analysis aims to address and economic outcomes in different portions of this challenge by investigating key areas to better the basin. Sensitivity analyses were combined understand localized views and responses to on the first two assumptions by constructing nine flooding and to generate key themes around flood cases representing all low, medium, and high management from the local level. It does not attempt combinations of the economic value of water to to draw a representative sample of the basin. irrigation and downstream low flow augmentation. These assumptions are shown in Table 6. Focus group discussions were organized in sites that face problems of (1) chronic flooding, (2) drought, Social Analysis (3) water quality issues, and (4) salinity intrusion. The social analysis complements the hydrological Focus group discussions were conducted with men and economic modeling sections by providing a and women in about 20 districts across India and demographic overview of the Ganges Basin, and Bangladesh in coastal areas and the lower plains. Table 6 Assumptions of Irrigation and Low-Flow Values in the Economic Optimization Model Economic value Low (US$/m3) Medium High Value of low flows to the delta above Farakka Barrage minimum for Jan-May 0.00 0.05 0.10 Value of water in irrigation 0.01 0.05 0.10 47 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 34 Site Map of Focus Group Discussions Focus Focus Focus Group Focus Locations Group Group Locations Locations Group Locations Drought Drought Drought Drought Flood FloodFlood Flood Water Water Quality Water Quality Quality Water Quality Salinity/ Salinity/ Salinity/ Biodiversity Biodiversity Biodiversity Salinity/ Biodiversity 48 4. Ten Fundamental Questions Fundamental environmental, economic, Ganges Basin. Instead, it was created to stimulate and social questions must be answered to discussion of some of the most critical issues with guide informed decisions on the sustainable which riparian countries will need to grapple as they management and development of the Ganges manage and develop their shared water resources. Basin’s resources. This section asks key questions that can help focus future efforts to explore the Question 1. potential and limitations of water resources Is there Substantial Potential for Upstream development in the Ganges Basin. We pose ten Reservoir Storage in the Himalayan fundamental questions, describe the commonly held Headwaters of the Basin? perceptions48 on the answers to these questions, and then provide answers and insights based on the Perception: Yes new information obtained from our modeling and Much has been written about the potential for large analysis. The ten questions are: water storage structures in the Himalaya. It is generally assumed that this potential could be harnessed 1. Is there substantial potential for upstream reservoir through large multipurpose dams to produce storage in the Himalayan headwaters of the basin? hydropower, deliver more timely irrigation water, and 2. Can upstream water storage control basinwide regulate the extreme flows of the Ganges River. flooding? 3. Can upstream water storage augment low flows Findings: Not Really downstream? 4. Are there good alternatives or complements to Although many sites are attractive for the reservoir storage? development of multipurpose water storage 5. Is there substantial untapped hydropower infrastructure, the steep terrain and deep gorges potential in the Ganges Basin? allow surprisingly little water to be stored behind 6. What is the magnitude of potential economic even very tall dams. Developing the full range of benefits from multipurpose water infrastructure, structures under consideration in this report would and what are the tradeoffs among different provide additional active system storage equivalent water uses? to only about 18 percent of annual average flow, 7. What are the cost- and benefit-sharing dynamics which is not very significant on a basinwide scale. of upstream water storage development? 8. Is infrastructure the best strategy for protecting Even if every one of the 23 large dam sites identified communities from floods? in Nepal were developed, the aggregate active 9. Is it possible to control sediment in the Ganges? storage on the river system would be only about 10. What will climate change mean for the basin? 130–145 billion cubic meters, of which about one third already exists. This amount of storage is quite This list is not an exhaustive set of questions about small compared with the 500 billion-cubic-meter the dynamics of and development options for the average annual flow of the Ganges River 48 By necessity, these summarized perceptions are broad generalizations that do not represent the range of perspectives and insights offered by researchers, journalists, and government officials in the region and abroad. Many have written on these issues and come to conclusions that are similar as those reached in this report. 49 49 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks (Figure 35). For comparison, storage capacity on not create the substantial storage that is generally many rivers is 100–200 percent of the mean annual available behind tall dams in less steep areas. flow. For example, the Colorado River’s storage capacity is roughly 250 percent of mean annual Table 7 presents the major existing and proposed flow. Storage on the Nile is about 300 percent. dams in the Ganges system with heights of more than 100 meters. Even though many of these dams The topography of the Ganges system simply does would be among the tallest in the world, they would not allow for storage of large volumes of water. provide surprisingly little storage. In Egypt’s flat Furthermore, developing even the modest 130–145 terrain, the Aswan High Dam, with a height of 111 billion-cubic-meter storage potential on the Ganges meters, can store 162 billion cubic meters of water, would be very expensive; the 23 large infrastructures whereas the Andhi Khola Dam site on the Kali proposed would require capital investment of Gandaki River in Nepal, with a comparable height roughly US$35 billion (2010 dollars) and likely of 110 meters, would store only 0.9 billion cubic take at least 30 years to construct.49 Why is there so meters. little storage capacity when there are so many dam sites? The Himalaya offer many opportunities for A distinction is made between a dam’s active (live) the development of multipurpose storage dams that storage and its gross (or total) storage. Most dams could produce hydropower and provide water for are designed to have only a portion of their storage drinking, industrial supplies, and irrigation. However, actually accessible every year while the remaining the rugged topography and steep mountains (Figure (dead) storage is reserved for sediment storage. 36: Gradients of Selected Himalayan Rivers) do not To understand the potential of system storage to allow for large reservoirs, thus Himalayan dams do regulate flows, one must compare the active storage with the mean annual flow or high flows of the river. For example, as shown in Table 7, the Chisapani Figure 35 Dam on the Karnali River in Nepal has the highest Current and Potential Surface Water Storage in the Ganges Basin proposed storage in the Ganges system at 28.2 billion cubic meters of gross storage; however, its 600 – usable live capacity is only 16.2 billion cubic meters. Since the average annual flow of the Karnali River at 500 – the Chisapani site is approximately 44 billion cubic meters (with monsoon flows alone ranging from 22 400 – to 47 billion cubic meters depending on the year), Volume (km3) 300 – even this dam, with the largest storage capacity of any identified dam site in the Ganges Basin, would 200 – not be able to provide over-year storage or store the 100 – full monsoon flow. 0– Despite often polarized views on this debate, Average annual Baseline Active Total Protential flow Storage Active Storage of All dams are not good or bad per se. As the following Dams (baseline + questions indicate, in addition to detailed 23 dams, including mega dams) individual project-level analyses, it is critical to 49 Dams could arguably be built in the middle and lower reaches of the river basin, but alluvial plains are not generally favorable for dam construction, and the combination of high temperatures and flat reservoirs with high surface area-to-volume ratios would lead to large evaporation losses. Plus, because of the very high population density in the Ganges plain, dams with large surface area would have great impacts in terms of resettlement. 50 Ten Fundamental Questions understand the systemwide implications of, and Findings: Not Really alternatives to, dams. Although a moderate amount of flow could be stored at the subbasin level, this storage is Question 2. unlikely to significantly reduce flooding because Can Upstream Water Storage Control Basin it is generally not the level of peak flows in major Wide Flooding? (usually embanked) tributaries that causes flooding, but rather localized rainfall, high flows in smaller Perception: Yes tributaries, and embankment failures. Himalayan storage reservoirs are commonly seen as the answer to the flooding that plagues the Ganges At the basinwide level, the storage potential is plains and delta, especially in areas of Bangladesh, simply too small to meaningfully regulate the full Bihar, and eastern Uttar Pradesh. river system. The modest scale of potential active Figure 36 Gradients of Selected Himalayan Rivers River Slopes - Karnali Basin 7,000 – 6,000 – 5,000 – Elevation (m) 4,000 – Bheri Seli 3,000 – Mugu Kamali 2,000 – Humla Kanali 1,000 – W.Rapti-Jhimruk Khola 0– W.Rapti-Marikhila l l l l l 0 100 200 300 400 500 Distance from Nepal-India Border (km) River Slopes - Gandaki River Basin 7,000 – 6,000 – 5,000 – Elevation (m) Narayani 4,000 – Rapti 3,000 – Maryandi 2,000 – BhuriGandaki 1,000 – Trisuli KaliGandaki 0– l l l l l l l l l l 0 50 100 150 200 250 300 350 400 450 500 Distance from Nepal-India Border (km) 51 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Table 7 Existing and Proposed Dams in the Ganges Basin over 100m High, with Global Comparators Dam River Total height (m) Gross Storage Capacity (BCM) Existing Tehri Bhagirathi 261 3.5 Marsyangdi Marsyangdi 240 6 Lakhwar (Under construction) Yamuna 204 0.6 Utyasu (Under construction) Alaknanda 175 3.7 Kalagadh Ramganga 128 0.3 Kulekhani Bagmati 107 0.1 Proposed Budhi Gandaki Budhi Gandaki 300 3.2 Upper Karnali Karnali 260 7 Bheri 4 Bheri 260 15.8 Kali Gandaki A Kali Gandaki 260 6.9 Pancheshwar Sarda 250 6.8 West Seti (Seti 6) West Seti 240 3.1 Chisapani Karnali 240 28.2 Sapta Koshi High Koshi 220 13.5 Seti 1 West Seti 195 1.5 Sun Khosi Sunkoshi 180 1.5 Kali Gandaki 2 Kaligandaki 160 5.1 Purnagiri Sarda 150 3.4 Tamur Mewa Tamur 150 1.9 Seti Seti 145 4 Trisuli Trisuli 140 11.0 Andhi Khola Kali Gandaki 110 0.9 International Dams Gross Storage Capacity (BCM) River Total height (m) Nurek1 Vakhsh, Tajikistan 300 a 10.5 Hoover2 Colorado, USA 221 35.2 Three Gorges 3 Yangtze, China 175 39.3 Aswan4 Nile, Egypt 111 169 Sources: This table was compiled from a variety of sources and expert interviews to reflect the range of large dams under discussion by governments and stakeholders. It is not an official list of planned investments. 1. Ghasimi 1994, p. 138. 2. Cech 2010, p. 223. 3. Chinese National Committee on Large Dams, 2011. 4. Abu-Zeid and El-Shibini 1997, pp. 209-217. Note: a. the tallest dam in the world. 52 Ten Fundamental Questions storage severely limits riparians’ ability to ever Flooding across the Ganges Basin is extensive and truly regulate this river system, even assuming an devastating, but so routine that it often receives aggressive development of storage infrastructure. On little attention. Figure 37 shows flooded areas the positive side, fewer dams will preserve a more over the years throughout the Ganges plains and natural hydrology in the river system, which provides delta. Upstream storage has long been considered a wide variety of services. a promising way to control these floods.50 Given the Figure 37 Flooded Areas in the Ganges Basin Ganges Basin Flooded lands in: International boundaries 2008 2007 2006 2005 States 2004 2003 2001 Rivers Source: Based on data from RMSI Pvt. Ltd. and Dartmouth Flood Observatory. 50 For example: Sanjeev K. Verma, ‘Dams in Nepal Only Way to Check Floods,’ The Times of India (Patna Edition), August 27, 2008; ‘India and Nepal Negotiate Dam Construction Project’, NDTV News, May 26, 2011, http://english.ntdtv.com/ntdtv_en/news_asia/2011-05-26/india-and-nepal-negotiate-dam-construction-project.html (Accessed September 6, 2011); ‘India-Nepal to Talk on Building Dams to Stop Floods,’ Webindia123.com, May 25, 2011, http://news.webindia123.com/news/articles/ India/20110525/1757253.html (accessed September 2, 2011); and ‘Nepal-India Meet on Inundation in Progress,’ Kathmandu Post, October 8, 2002. Opposing views are fewer, but also expressed, see Surendra Phuyal, ‘Dams Do Not Solve Flood Problems of Bihar,’ March 1, 2001; Navin Singh Khadka, ‘The Mother of All Floods,’ The Nepali Times, August 8-14, 2003. 53 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks flat topography of the plains and delta, attention flood preparedness and early warning systems, has focused on dams in the upstream mountainous along with land zoning and insurance, are essential regions. The floods in the Ganges plains and delta, flood-protection strategies. however, are the result of several phenomena: (1) heavy rainfall and overland flow outside the main Over the years, because of the particularly stem of the rivers, (2) breaches in embankments, devastating nature of the regular floods in eastern (3) rising rivers that are not fully embanked, or (4) Bihar near the Kosi River (also known as the overtopping of embankments. Upstream storage ‘Sorrow of Bihar’ because of these destructive and improved embankment construction and events), special attention has been given to the management may help in some cases. However, potential of the Kosi High Dam for reducing flood many floods are caused by rising waters on rivers impacts. The dam site is in Nepal approximately 40 that do not have significant upstream dam sites, or kilometers north of the Nepal-India border. Box 3 by heavy rains that find no drainage. In these cases, gives an idea of the causes, frequency, and severity Box 3 A Chronology of Recent Floods in Bihar 1998: High river discharges in most rivers in North Bihar in the first week of July cause embankments of Burhi Gandak, Bagmati, Adhwara and Kosi to be partially damaged. 1999: Unexpectedly heavy rains in October threaten the Kamla Balan river system and Kosi spurs. 2000: Kamla Balan and Bhutahi Balan catchments receive heavy rainfall in first and last week of July, causing flooding. In first week of August, Eastern Kosi embankment punctured. 2001: North Bihar is very flood affected. Western Kosi embankment, Bhutahi Balan right embankment, Bagmati left embankment and Burhi Gandak left embankment are partially damaged. 2002: North Bihar again experiences serious flooding caused by overtopping of Kamla Balan left embankment and Khiroi right embankment. 2003: Flood levels at Patna breaks 1994 record in Ganga and downstream. Bhagalpur breaks 1978 record. Status in rivers other than Ganga and Gandak is normal. 2004: Initial monsoon rains in the first week of July break previous three years’ flood record and surpass the 1987 flood in north Bihar. Bagmati, Burhi Gandak, Kamla Balan, Bhutahi Balan, and Adhwara group of rivers set new flood level records. Embankments breach in 53 locations, inundating a vast area of north Bihar and causing widespread damage and loss of life. Kosi remains normal. 2005, 2006: Normal floods. 2007: Very serious flooding in north Bihar. Heavy rainfall at beginning of flood season, with regular continuing rainfall in July and August, keep the Burhi Gandak and Bagmati rising. About 28 embankment breaches occur, affecting nearly the whole of north Bihar with floods and consequent heavy losses of life and livelihoods. 2008: Kosi embankment breached on August 18 at Kusha in Nepal causing the entire river to divert to an old channel, flooding areas that had not been flooded in hundreds of years. Source: Primarily from Bihar Flood Management Information System (FMIS) 54 Ten Fundamental Questions of these floods. Figure 38: Flood-Related Deaths The models indicate that in many years, current flood and Flood-Affected People in Bihar demonstrates peaks in the Kosi River (in red) can be brought down how Bihar has always been impacted by floods, by building such a dam (in blue) and by leaving a with hundreds dying and tens of millions of people substantial ‘flood cushion’51 when operating the affected year after year. dam. The exceptions are years such as 2003 when a closely occurring ‘second peak’ event occurs. It is often assumed that if a large dam, such as the Even if the dam reservoir is empty at the beginning proposed Kosi High Dam, were built upstream of of the monsoon, it would be completely filled after Bihar, these devastating floods could be controlled. capturing the first flood peak. It could not be re- To examine this question, the simulation models emptied in time to hold back the second flood peak. were run with various operating rules. The rules were chosen to balance the often-competing uses Even the very large proposed Kosi High Dam, of storage – to control floods, generate hydropower, however, cannot eliminate flood peaks and spread and meet irrigation and other demands. Flows were the hydrograph smoothly throughout the year simulated on the Kosi River near the proposed Kosi because the dam, which provides only 9.5 billion High Dam site for four infrastructure options: cubic meters of live storage, would be built on a (1) existing infrastructure, (2) with the proposed Kosi river with an average annual flow of 55 billion cubic Dam, (3) with the three proposed mega-dams, and meters (much higher in many years). The dam could (4) with all major planned dams in Nepal. thus regulate only a small part of the monsoon Figure 39 presents the results. flows, even in low-flow years. Figure 38 Flood-Related Deaths and Flood-Affected People in Bihar 1600 – – 35,000,000 1400 – – 30,000,000 1200 – Flood-related Death – 25,000,000 People Affected 1000 – – 20,000,000 800 – – 15,000,000 600 – – 10,000,000 400 – – 5,000,000 200 – 0 – | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | –0 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Deaths People Affected Source: Disaster Management Department, Government of Bihar. 51 A flood cushion is created by lowering the water level in a dam reservoir to make space to capture anticipated flood waters. Lowering dam reservoir levels, however, creates tradeoffs with hydropower and irrigation uses where higher levels are generally more productive. 55 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 39 Flood Peaks on the Kosi River under Different Infrastructure Scenarios 8000 – 7000 – 6000 – 5000 – Flow (m3/s) 4000 – 3000 – 2000 – 1000 – 0– l l l l l l l l l l l l l l l Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 Jul-01 Jan-02 Jul-02 Jan-03 Jul-03 Jan-04 Jul-04 Jan-05 Jul-05 Jan-06 Jul-06 Base Scenario E and G Scenario H Scenario E = Kosi Dam, Scenario G = Megadams (Kosi, Pancheswar, and Chisapani) and Scenario H = all major planned dams in Nepal Note: The shape of the flows downstream of the Kosi High Dam in this graph is an artifact of the modeled operating rules considered in this MIKE-BASIN simulation model run. In reality, these flows are much smoother. The important question, however, is not The role of embankments (levees): The Kosi whether the Kosi High Dam can reduce River, like other major tributaries of the Ganges flood peaks in the Kosi River; but whether flowing from Nepal to India, is fully embanked. reducing flood peaks in the river will diminish Moreover, the Kosi embankments have never been flooding events in Nepal and Bihar. The overtopped. Bringing down the flood peaks answer, unfortunately, is ‘not really’ – for the within the Kosi embankments is unlikely to following reasons: affect the lands outside the embankments, and it is unlikely to make much of a difference Figure 40 superimposes basin boundaries over the inside the embankments where people expect areas that were impacted by floods over the past flooding. Embankments are generally oversized to decade. The image shows that most of the flooding allow for river movement and extremely high flood in Nepal and Bihar lies outside the Kosi flows. Therefore, in theory, flood flows in embanked subbasin. The development of the Kosi High Dam or rivers (even without an upstream dam) should not any other flood-control infrastructure upstream in the overflow and cause flooding damage. Kosi River will impact only a small part of the flood- affected areas downstream. The majority of floods are However, people cultivate land and even live within a consequence of intense local rainfall and/or high the embankments in this poor, densely populated flows in other river systems that would not be affected area. In fact, some 2 million people live in 380 by building the Kosi High Dam. villages within the Kosi embankment.52 In addition, 52 Singh et al., 2009. 56 Ten Fundamental Questions Figure 40 Flooded Areas and Kosi Basin Boundaries Major rivers Ganges Basin International boundaries Kosi Basin Indian States Sub-basins Flood Intensity (past decade) Capital cities Major cities Cities and towns in Kosi Basin Other cities Low High Very High Source: Based on data from RMSI Pvt. Ltd. and Dartmouth Flood Observatory. 57 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 41 Embankments in the Ganges Basin Flooded lands in: 2008 2007 2006 2005 2004 2003 2001 Major rivers Ganges Basin Embankments International boundaries Kosi States Source: Based on data from RMSI Pvt. Ltd. and Dartmouth Flood Observatory. 58 Ten Fundamental Questions many embankments in the basin were poorly Embankments have a mixed history in Bihar. constructed and are generally poorly maintained In 1952, there were only 160 kilometers of (Figure 41). The Kosi ‘floods’ of 2008 were caused embankments in Bihar. The ‘Kosi Project,’ inspired by by a breach in the Kosi embankment in Nepal (which a 1953 visit of high-level officials to the Hwang-Ho is maintained by the Government of Bihar under embankments of the Yellow River in China, was a the Kosi Treaty). This breach made more than 3 massive embankment-building campaign beginning million people homeless as the Kosi burst out of its in 1955. Bihar now has about 3,500 kilometers of embankments and moved to an old river channel embankments, mostly in flood-prone north Bihar abandoned a few centuries ago. The event led to a (Figure 42).53 Still, large areas of the state remain major six-month engineering effort to guide the river flood prone despite (or, some contend, partly back within its embankments. Further illustrating the because of) the embankments. The longstanding disconnect between peak river flows and flood events, debate over the value of embankments is discussed the 2008 breach actually occurred when flows later in this section. were quite low, nowhere near flood levels, which indicates an urgent need to improve embankment A single infrastructure project like the Kosi High maintenance systems Any intensification of flows, Dam cannot eliminate floods in Bihar. A balanced for example as a consequence of climate change, approach examining all possible structural and would reinforce the need for robust embankment nonstructural interventions is needed. Investments maintenance systems coupled with ‘soft’ flood- in real-time hydromet systems and modernization of management systems. (See Question 8.) forecasting and warning systems may be the Figure 42 Timeline of Major Damage to the Kosi Embankments 2008: Eastern Embankment breaches at Kusha in Nepal 1963: Western Embankment breach at Dalwa in Nepal (loss lesser as river receded after eroding embankment) (recently-constructed embankment section collapsed) 1991: Western Embankment near Joginia in Nepal (less loss as river receded just after 2km breach) 1971: At Bhatania approach near Bhimnagara 1980: Eastern Embankment in Saharsa district 1984: Eastern Embankment in Saharsa district (500,000 displaced, 96 villages submerged) (major disaster even though not high flow, 2000: Eastern Kosi afflux bund punctured 1968: At 5 locations in Dharbanga (due to highest flow recorded) 2.3 m people displaced) 1960s 1970s 1980s 1990s 2000s Source: Bihar Flood Management Information System (FMIS) 53 Singh et al., 2009 and Mishra 2008. 59 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks best strategy in the short run, and possibly even any notable difference in the monsoon flows in the in the longer run. Co-benefits of such investments main river channel near the India-Bangladesh border. include enhanced information for farmers to time their planting and fertilizing, and the collection Similarly, the models produced flood maps for the of time series hydromet data needed for climate Ganges delta in Bangladesh corresponding to two change monitoring and modeling. infrastructure options: (1) the base case and (2) with all potential dams built. The maps (Figure 44) The broader, basinwide question is show that there is no perceptible difference on the unequivocally answered by our analysis. area flooded in the Ganges-dependent parts of Can Himalayan dams control floods in the Bangladesh even when the full suite of dams is built main-stem Ganges as far downstream as in Nepal. Bangladesh? No. The storage capacity of Himalayan dams is so The models were run to simulate changes in flow small compared with the full flow of the river measured on the Ganges main-stem at Hardinge that once the modified flows of a dammed Bridge in Bangladesh (near the India-Bangladesh tributary reach the main-stem, the river’s border). The simulation hydrographs under the base- ‘memory’ of that storage is lost. The flow in any case scenario and a few scenarios with all 23 major given tributary is only a fraction of the peak monsoon Nepal dams (including the three megadams) show flow in the main-stem of the Ganges. Even if several that the flood peaks are virtually indistinguishable tributaries are dammed, the effect is insignificant (Figure 43). There is no change in the flood peaks because there is so much water in the main-stem. because the system storage is insufficient to make This is particularly true in the years with highest flows. Figure 43 Flood Peaks at the India-Bangladesh Border under Different Infrastructure Options Base Scenario F Scenario G Scenario H 60,000 50,000 40,000 30,000 20,000 10,000 0 Jan-99 Jul-99 Jan-00 Jul-00 Jan-01 Jul-01 Jan-02 Jul-02 Jan-03 Jul-03 Jan-04 Jul-04 Jan-05 Jul-05 Jan-06 Jul-06 Source: IWM (2010). Note: The different scenarios relate to which dams were considered operational as follows: Scenario E = Kosi Dam, Scenario F = Pancheswar Dam on the Sarda, Scenario G = Mega Dams (Kosi, Pancheswar, and Chisapani), Scenario H = All planned major dams in Nepal 60 Question 3. significant if all the large dams under consideration Can Upstream Water Storage Augment Low were built, approximately doubling low flows in the Flows Downstream? driest months. Shifting even a minor portion of the flood flows to the dry season could significantly Perception: Yes increase low flows especially in a very dry years. Low-flow augmentation may be large relative to In addition to holding back floods, these reservoirs current low flow, but it is negligible compared with are expected to release water stored during the wet peak flow, so the integrity of the hydrological system season for use in the dry season. This release would as it currently stands is unlikely to be threatened by augment low flows for ecosystems, agriculture, and infrastructure development. other uses across the basin, especially in the dry months preceding the monsoon. However, the economic value of this additional low-flow augmentation is unclear because of soil Findings: Yes, But... waterlogging and low agricultural productivity in India and Bangladesh. Water is not currently the In physical terms, the modeling results confirm this crucial constraint to agricultural productivity in the expectation. Low-flow augmentation could indeed be specific parts of the Ganges Basin that could receive Figure 44 Flood-Impacted Areas in the Ganges Delta under Different Infrastructure Options Negligible impact on the main-stem Ganges Legend Legend Rivers Rivers District Boundary District Boundary Polder Area Polder Area Flood Depth (cm) Flood Depth (cm) Flood Free Flood Free 10 - 30 10 - 30 >30 - 60 >30 - 60 >60 - 90 >60 - 90 >90 - 180 >90 - 180 >180 - 360 >180 - 360 >360 - 500 >360 - 500 >500 >500 Base Case All Potential Dams Built Simulated Extent of Flood Area for 2004 Peak Flows in Bangladesh Coastal Region Source: IWM (2010). 61 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks additional flows. Even if these dams were built (at high that would be possible under different development costs and likely over decades), increased productivity scenarios. The ‘with dams’ options (blue and purple would require agricultural modernization that would be lines) are much smoother than the base-case option beneficial regardless of upstream dam construction. (red line), meaning the dams would lessen flood peaks and raise low flows. In particular, note that The effects of increased low flows may make in the dry months of November through March the important contributions to enhancing ecosystem and scenarios with upstream regulation have significantly navigation services in the Sundarbans, an important higher flows than the base case (Figure 45). issue that requires additional research. In the main-stem Ganges River, the scenario with Nepal’s rivers contribute about 70 percent of low flows all Nepal dams built shows that low flows in most to the Ganges. Most of these low flows are sustained of the dry months could be doubled, even allowing by groundwater base flow and snow or glacier for some additional water withdrawals upstream melt, since current storage in the system is limited. (Figure 46). However, the distribution and use of Furthermore, much of this low flow is currently used in these additional low flows (which could reach India. Barrages in Uttar Pradesh and Bihar divert water about 54 billion cubic meters per year) would from the Himalayan tributaries that provide most of the depend on the outcome of negotiations among the system’s low flows for use in large irrigation systems. riparian countries. Increased storage capacity upstream would allow for delayed releases of modest amounts of monsoon The three mega-dams together would add about 33 water that ordinarily flow through the system with billion cubic meters per year to dry season flow, and the flood. Even a minor portion of the massive flood the smaller Himalayan projects together would add peaks can make a sizeable difference in increasing the about 22 billion cubic meters. The Kosi High Dam minimal low flows in the Ganges today. by itself would provide only a marginal amount of low-flow augmentation. The volume of potential low- Figure 39 shows the transfer of water from the flow augmentation varies only slightly with annual wet to the dry season in the Kosi tributary system hydrological variability. Figure 45 Figure 46 Low Flows on the Kosi River under Different Low Flows on the Ganges at Hardinge Bridge Infrastructure Options, 1998–2007 15000 20,000 18,000 12500 16,000 Flow (MCM/month) Flow (BCM/month) 10000 14,000 12,000 7500 10,000 8,000 5000 6,000 2500 4,000 2,000 0 – Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Nov Dec Jan Feb Mar Apr May Base With Kosi High Dam Base All Nepal Dams Source: MIKE BASIN Model, IWM (2010). Source: IWM (2010). 62 Ten Fundamental Questions The economic model suggests that the optimal purposes: to increase surface water irrigation in allocation of this low-flow augmentation is Nepal and/or India, to increase diversions to Kolkata sensitive to assumptions about the value of water. through the Hooghly River, or to increase low flows If the economic productivity of water in India and into the delta and the Gorai region. The best option Nepal is high relative to its value in Bangladesh, is not obvious given that evidence suggests the upstream irrigation schemes (potential new ones in productivity of irrigation water in the Ganges plains Nepal, and existing ones in India) could use these is low,55 and given the uncertain impacts or benefits additional flows (Table 8). Thus, if new Nepalese of low-flow augmentation in the Ganges delta (e.g. irrigation schemes were developed alongside the for salinity intrusion management). All of these dam projects, the economic model would allocate options need to be investigated further.56 them up to 32 percent of the additional water in the dry season, while Indian irrigation schemes would One important issue associated with low flows is the be allocated the balance.54 If the value of water health of the Gorai distributary system in southwest downstream were higher for irrigation or ecosystem Bangladesh. The Gorai, home to tens of millions of uses, then the economic optimization model would people and a fragile mangrove ecosystem, is believed allocate a larger share of water to flow downstream. to have once been the main outlet of the Ganges. In reality, the distribution and use of these additional But the Ganges has meandered eastward and now low flows would likely depend on the outcome of bypasses the Gorai and joins the Brahmaputra to negotiations among the riparian countries. form the primary Ganges-Brahmaputra-Meghna outlet east of the Gorai. Over time, sediment from the It is essential to interpret these low-flow Ganges’ enormous sediment load was deposited in augmentation results carefully because there the main river creating a sand bar at the mouth of the are alternative strategies for obtaining many Gorai. Today, a flow of 925 cubic meters is needed of the non-power co-benefits of these dams, at Hardinge Bridge to overtop this sand bar that and the best uses and values of enhanced otherwise cuts off the supply of Ganges main-stem low flows are uncertain. Although these models water to the Gorai River distributaries. If all the Nepal do indicate that upstream storage can substantially dams are built, the number of days when flows are increase low flows, it is not clear how valuable this less than the critical 925 cubic meters could in theory would be in economic terms or how best to allocate be halved (if dry-season abstractions did not increase the water. The water could be used for a variety of upstream), substantially enhancing flow into the Gorai Table 8 Low Flow Augmentation in Irrigation, as Allocated by the Economic Optimization Model Low Flow Augmentation in Irrigation 3 Mega-dams +20 Smaller All Major in Nepal Dams in Nepal Storages in Nepal Volume of additional water for upstream irrigation (BCM/year) 28 (23-28) 33 (28-33) 38 (32-38) Volume of additional water flowing to Bangladesh (BCM/year) 5 (2-5) 9 (5-9) 16 (12-16) Source: This table is derived from the Ganges SBA economic optimization model and assumes the marginal value of low-flow augmentation in all three countries is US$0.05 per cubic meter. For sensitivity analyses on these values, see Table 11. Note: The first number indicates the average year, with numbers in the bracket indicating the range. 54 The distribution of this water is sensitive to assumptions about the net economic benefits from irrigated agriculture in India and Nepal, and from low-flow augmentation in Bangladesh. 55 Sharma 2008. 56 Chowdhury 2005, Molden et al., 2001, and Rogers et al., 1998. 63 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks during the dry season. But even with the development Augmenting low flows in some areas may of these large dams, significant sustained dredging actually cause harm by increasing marginal efforts, requiring both capital investments and waterlogged areas and reducing productivity. institutional strengthening, would likely be needed. In contrast, modest river-training works combined with The net economic benefits of augmenting low flows a program of regular dredging at the mouth of the in a systemwide context are unclear. Gorai, could potentially sustain the Gorai even in the absence of upstream dam development. Could augmented low flows from upstream storage help manage water quality in India? Surprisingly, augmented low flows could actually Not really. reduce the productivity of some land. Many parts of India’s eastern Uttar Pradesh and Bihar have high In recent years, rapid urbanization and industrialization groundwater levels even in the pre-monsoon (lowest have produced more sewage and industrial pollutants, flow) season, which has led to significant waterlogging which flow directly into the Ganges. The Ganges Basin of the soil. In Uttar Pradesh alone, about 5 million is highly polluted, especially in the Yamuna near Delhi, hectares are waterlogged and a million hectares in the Kannauj- to-Varanasi stretch in eastern Uttar are saline (sodic) because of secondary salinization Pradesh, and also in the Ramganga-Kali tributaries due to high water tables and blocked drainage. in western Uttar Pradesh. Would upstream storage in Many of these areas recover slowly during the dry Nepal help improve the water quality downstream by season as they drain and soil moisture evaporates. increasing flows to dilute pollutants in the dry season? Figure 47 Ganges Water Quality in Critical Stretches Confluence of Nepal rivers Greatest Pollution 64 Ten Fundamental Questions Unfortunately, it does not appear promising. The and can be sustainably used. Increased strategic Himalayan rivers join the Ganges downstream of and sustainable use of this groundwater, within an Varanasi and therefore would not provide dilution appropriate policy and energy-pricing environment, benefits to the critical stretches, which are all upstream and in conjunction with a well-managed surface water (Figure 47). There might be water-quality benefits system, could provide water-supply benefits on a scale along the Ganges in Bihar, assuming low flows were comparable to the full suite of dams considered in this passed through the system and not abstracted for report, and it could possibly do so more immediately, irrigation, but they would be very modest relative the at national, state, or local levels, and at lower water quality challenge in this stretch of the Ganges. financial, social, and environmental cost. Moreover a It is also possible that water-quality benefits could be conjunctive-use strategy could be designed that would derived from judicious operation of existing Indian also help manage waterlogging in the basin, and reservoirs, particularly the Tehri Dam. enhance the reliability of water supplies to tail-end users in surface irrigation schemes and/or irrigators in Salinity could be affected by upstream storage the eastern reaches of the Ganges plain. dams. However, salinity levels in Bangladesh do not appear very sensitive to the different dam options. There This study has shown that surface water can be may be more complex and far reaching implications augmented during low-flow seasons if large-scale of salinity changes near the Bangladesh coast if the multipurpose water infrastructure is developed, and relative flows of the Ganges distributaries and the that irrigation is one possible use of the enhanced Padma/Jamuna/Meghna River change. In the extreme, low flows. Additional irrigation water could be used changes in these distributaries could potentially affect to extend the area covered by the winter (rabi) crops the direction of freshwater currents in the Bay of Bengal and improve the summer (kharif) crop by enabling that serve as a buffer against salinity increases in the moderately improved flood management in the Ganges-dependent coastal area. There is a clear need tributaries on which dams were built. to better understand how changes in water quality in the Gorai (southwest Bangladesh) might affect ecosystems The time and costs (financial, social, and and communities in this fragile delta region. environmental) involved in building 23 large dams, however, would be high, and similar Question 4. agricultural gains and/or low-flow enhancements Are there Good Alternatives or Complements could be achieved by other means. to Reservoir Storage? Most agricultural yields in the Ganges Basin are just Perception: No a fraction of Asian and global benchmarks, and Many believe that large human-created storage even of other areas in India. Increasing agricultural (dams) is the only option of adequate scale to productivity is a continual challenge. Investments meet the basin’s needs, given the region’s growing to enhance productivity could yield dramatic populations and economies. Although underground gains even in the absence of additional water aquifers, lakes, glaciers, snow, ice, and even soils are from upstream storage. Enhancing the productivity all forms of natural water storage, it is widely believed of existing agriculture would be much more efficient that these storages are relatively small, that the than expanding the irrigated area because it would not basin’s groundwater is being drastically overexploited, necessarily require additional land or water resources. and that its glaciers are melting rapidly. Investments in market infrastructure, cropping patterns, seeds, fertilizers and agrometeorological information Findings: Yes, underground could probably raise farmer productivity at less cost. Such investments would then enhance the economic Vast, aquifers in the central and lower reaches of value of any additional water, and hence the economic the Ganges Basin hold water in natural storage benefits of upstream storage if it were built. 65 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks The real strategic story, however, lies further estimated at just 33.5 percent (as compared with below the surface – the Ganges Basin has development in the Indus of 77.7 percent).57 one of the world’s greatest aquifer storages. The basin was formed by alluvial deposits from the The storage available in the shallow alluvial Himalaya, resulting in an aquifer that is several aquifers of eastern Uttar Pradesh and Bihar kilometers deep in some areas. It is a complex, is approximately 30– 50 billion cubic meters, multilayered system interspersed with clay layers comparable to the low-flow augmentation and perched aquifers and possibly an extensive (approximately 40–60 billion cubic meters, see deep aquifer as well, though this has not yet been Table 11) that could be achieved with explored (Figure 48). Although groundwater construction of 23 large and mega dams in overexploitation is a challenge across much of India, the Himalaya. Moreover, the water from upstream groundwater development in the Ganges Basin is dams would suffer evaporative and leakage losses Figure 48 Ganges Basin Groundwater Potential Groundwater recharge (mm/yr) Very High Medium Low Very high 300 100 20 2 low 0 In major groundwater basins Area of heavy ground water abstraction with In areas with complex over-exploitation hydrogeological structure In areas with local and shallow aquifers Source: Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) and UNESCO. http://www.whymap.org/whymap/EN/Products/products_node_en.html 66 Ten Fundamental Questions as it traveled downstream, and the timing of water to the extensive waterlogging and sodicity availability could not be targeted as precisely as the problems of the basin. Conjunctive use is being pumping of groundwater directly by a farmer onto undertaken today, but not in a planned manner. In his or her own fields. response to erratic supplies of surface water, many farmers have already started exploiting the plentiful The untapped potential of groundwater good-quality groundwater to irrigate crops and/or to storage was recognized most notably in a provide supplementary irrigation conjunctively with 1975 Science article, ‘The Ganges Water surface water. Surface water supplies are especially Machine.’57 The authors envisaged a massive unreliable at the tail ends of large, over-designed program of targeted groundwater pumping in irrigation systems. These systems were intended to the dry season to irrigate winter crops. In the wet spread the available water out over large areas rather season the groundwater would naturally recharge than meet demands reliably. For example, in the from the monsoon rains and the extensive ‘leaky’ Sarda-Sahayak canal system in eastern Uttar Pradesh, surface-water canal systems, with additional the designed performance covers 64 percent artificial recharge (pumping) of wet season flows irrigation intensity in kharif season (wet/summer) and into the aquifer. If this proposal proved practical, an only 36 percent in rabi season (dry/winter). enormous amount of water storage could be utilized. A well-managed scheme of conjunctive This seasonal use of the groundwater aquifer for surface and groundwater use could be water storage deserves careful economic comparison designed to diminish waterlogging and with Himalaya storage options. Groundwater storage better manage the water table. Waterlogging and pumping could prove to be a low-cost means of is most common at the head of large surface providing additional irrigation water during the dry irrigation schemes. The leakage from these schemes, season and preventing waterlogging. Large dams in combined with rainfall and the inability of the water the Himalaya could provide supplemental irrigation to drain back into canals, has caused extensive water during the dry season, but they would not waterlogging often up to a kilometer away from reduce waterlogging (and might exacerbate it); major irrigation canals (Figure 49). If farmers at the would take longer to plan and build; and would entail social and environmental disruptions and Figure 49 hazards. The main economic benefit of large dams Waterlogging Along the Sarda-Sahayak Canal System in India in the Himalaya would be hydropower generation, not irrigation. Groundwater storage and pumping would consume large amounts of electricity, so there could in fact be important complementarities between groundwater and Himalayan hydropower. Our findings suggest that the basic construct of the Ganges Water Machine – although not necessarily at the full scale envisaged in the paper – is sound. Ambitious, well-managed conjunctive use programs in targeted parts of the Ganges Basin could deliver substantial water storage, additional dry-season water, and a response Source: Nagaraja Harshadeep Rao (2010). 57 Revelle and Lakshminarayan 1975. 67 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks head of these canals irrigated their winter crops with be adjusted to encourage groundwater use where pumped groundwater, waterlogging could be better groundwater levels were high and/or land is controlled and the productivity of their land could be becoming waterlogged. Groundwater use could be enhanced. The surface water they would otherwise discouraged where water tables are falling. Energy have used could then be sent down to tail-end users pricing policies could be used to incentivize changes or left in the river for downstream/eastern farmers, in groundwater usage. Sophisticated groundwater or for other uses such as municipal supplies or mapping and monitoring would be needed. ecosystem and navigational services. An immediate opportunity to implement this The policy environment needed to convince these approach exists in Uttar Pradesh. Figure 50 farmers to use groundwater rather than surface water shows high groundwater levels throughout the dry in the dry season would admittedly be challenging, season in the Ghaghra-Gomti Basin, a subbasin of but tools are available. For example, the rosters the Ganges in the eastern part of Uttar Pradesh, which dictating water delivery from surface canals could has significant potential for enhanced groundwater Figure 50 High Groundwater Tables in Ghaghra-Gomti Basin in Uttar Pradesh, India Uttar Pradesh Ghagra Gomti Basin Pre-Monsoon Water Levels Location of GGB Pre Monsoon 2004 in Uttar Pradesh Legend Canals GGB System Boundary Pre-Monsoon 2004 0-3 3-5 5-8 0 20 40 80 120 >8 Kilometers Post-Monsoon Water Levels Post Monsoon 2004 Legend Canals GGB System Boundary Post-Monsoon 2004 0-3 3-5 5-8 0 20 40 80 120 >8 Kilometers Legend Canals GGB System Boundary 0 - 3 m deep 3 - 5 m deep 5 - 8 m deep > 8 m deep Source: SMEC (2009). 68 Ten Fundamental Questions irrigation. If supported by a well-designed conjunctive- Question 5. use program, additional groundwater use could Is there Substantial Untapped Hydropower significantly enhance land, water, and agricultural Potential in the Ganges Basin? productivity. A detailed study58 suggests that in this Perception: Yes subbasin, 2.5 million tubewells (in addition to the 1.75 million now in place) could The Himalaya have enormous hydropower potential. sustainably pump more than 20 billion cubic This power is seen as a source of domestic energy meters of additional groundwater, a scale supplies as well as a source of export revenues for of lean-season water supply augmentation Nepal where potential supplies far outstrip potential roughly comparable to that provided by demand. It is also seen as an important source the full suite of large dams currently under of clean energy in a region that is experiencing high consideration in the Ganges Himalaya.59 growth. These findings do not suggest that upstream Finding: Yes dams are necessarily a poor investment, nor do In Nepal alone, it is estimated that more than they suggest that downstream benefits should be 40,000 megawatts of economically feasible potential ignored. This section explores just a subset of the hydropower exists in the Himalayan headwaters of the benefits those structures could potentially provide. If Ganges. Less than 2 percent has been developed. The upstream multipurpose dams are found to be suite of dams examined in this report, the largest 23 economically, socially, and environmentally in Nepal, would have an installed capacity of about justified by the bundle of benefits they can 25,000 megawatts, producing an estimated 65-70 produce (predominantly hydropower, as will terrawatt hours of power annually (and saving up to be discussed later), then additional dry-season 52,000–56,000 tonnes of carbon equivalent per year.) water could be an important co-benefit. The net value of this potential hydropower is estimated Although upstream storage is probably not the best at some $5 billion annually, quite significant relative to option for delivering increased dry-season irrigation Nepal’s 2011 gross domestic product (GDP) of $18.9 water, it could be an attractive complementary billion (current US $).61 investment to more immediate interventions in To answer this question, a number of modeling conjunctive use. For example, immediate investments runs (with both the water simulation and economic to improve the conjunctive use of groundwater and optimization models) were carried out to represent surface water could enhance agricultural productivity, the current baseline condition and scenarios with which, in turn, would raise the value of any additional combinations of the three often-discussed mega-dams low-season agricultural water that might eventually in Nepal (Pancheshwar Dam on the Mahakali/Sarda be delivered by upstream dams. Alternatively, if River; Chisapani Dam on Karnali/Ghagara River; and the productivity of agriculture were strengthened Kosi High Dam on the Kosi River), as well as for 20 to the extent that demand for irrigation water was smaller dams in Nepal. The results were not surprising. diminished, enhanced low flows could be readily allocated to a range of other important in-stream Yes, there is substantial hydropower potential uses including ecosystems and navigational services.60 in Nepal. Just the three mega-dams with 58 SMEC 2009. 59 In comparison, the 23 dams under consideration could yield some 38 billion cubic meters of additional water for irrigation (Table 8). Evaporative losses and leakages, however, can be anticipated to approach 50 percent before the water would arrive on farms downstream. Add to this the inefficiency of farmers being unable to control surface water timing as effectively as they can control groundwater application, and the productivity gains of the two scenarios become roughly comparable. 60 This is not to imply that ecosystems and navigational services should be subordinated to agricultural water uses. It is only to note that there should be little concern that investments focused on the productivity of irrigation water would lead to a situation in which the water that was saved would have no other use or value. 61 World Bank 2009, World Development Indicators. 69 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks 19,000 megawatts of installed capacity being implemented and explored. India and Nepal could produce 35–45 terawatt hours of have agreed to build a cross-border transmission electricity annually. The remaining 11 dams line. Discussions are underway regarding a similar in the water systems model, representing investment between India and Bangladesh. 4,600 megawatts of installed capacity, could generate at least 18 terawatt hours Whereas most observers tend to focus on the annually. Including the 20 smaller dams in installed capacity of a power plant (in megawatts) the economic model yields another 26–30 when discussing hydropower potential, which is terawatt hours per year. Current hydropower important for high-value peak load potential, the production in the entire Ganges Basin is about 12 actual power generation (e.g. in megawatt-hours) terawatt hours annually and the current installed from the system is critical for assessing economic hydropower capacity in Nepal is only about 644 benefits.65 Power generation reflects the hydrology of megawatts.62 The new dams considered in this study the river and the size of the reservoir. For example, are all located in Nepal (Pancheshwar is on a border as shown by the modeling analysis, the Kosi High river with India), where domestic demand is much Dam has an installed capacity of only 3,500 less than the magnitudes of potential production megawatts, but can produce more power than the discussed here. Nepal’s peak demand is projected Chisapani Dam with an installed capacity of more to grow to 1,733 megawatts by 2019–2020.63 than 10,000 megawatts. Similarly, the 20 smaller dams have just over a quarter of the installed The Government of India has repeatedly stated its capacity of the three mega-dams, but they can interest in importing Nepal’s surplus, hydropower. generate more than half the power of the full suite of This could slow the growth in greenhouse gas dams (Figure 51) indicates that seasonal variations emissions in India and be beneficial for the India- in hydropower production from storage dams in Nepal trade balance. If this power were sold in India, where a conversion factor of 0.8 kilograms the Ganges Basin would probably be considerable, per kilowatt hour is used to reflect the power mix and given the limited storage available and the short calculate carbon savings, 65–70 terawatt hours of monsoon season. This is even more so in the case hydropower would save more than 52,000–56,000 for run-of-the-river projects that have no storage tonnes per year of carbon equivalent. Additionally, dams, unless they are regulated by a significant power exports from Nepal to India could help storage upstream that can provide a more consistent correct Nepal’s persistent balance-of-payments flow throughout the year. Thus, rather than delivering deficit with India. Today, Nepal imports power power consistent with full installed capacity from India. (megawatts) of these dams throughout the year, actual power generated will be lower and marked by Although it would take many years to design and seasonal fluctuations (Figure 52). build large hydropower in Nepal, particularly if transboundary negotiations are required, it is clear In addition to intra-annual (seasonal) variability, it that this is a region with rising energy demand is important to recognize that these flows are highly in the medium term. India alone has a projected variable from year to year. Hydropower production shortfall of about 100,000 megawatts by 2017.64 A will therefore display strong inter-annual fluctuations range of cross-border transmission projects are now since the system has no over-year storage. 62 Nepal Electricity Authority 2010. 63 Nepal Electricity Authority 2011. 64 Karki 2007. 65 Installed capacity is the theoretical capacity of all of the turbines in a power plant if they were run at full design capacity year round. In a monsoonal climate like the Ganges in the absence of very large-scale storage, there will be many months each year without adequate river flows to run all turbines at their full capacity. 70 Ten Fundamental Questions Our results indicate that there is indeed substantial a statement could be made about its feasibility. potential for regionally significant hydropower Constructing large dams in the difficult Himalayan generation in Nepal. Importantly, however, this report terrain and building transmission lines from isolated does not provide analysis of specific projects. The and inaccessible areas could be very costly and could development of any specific project would require result in significant environmental and social impacts financial, environmental, social, and technical (i.e., that would need to be mitigated. It should also be engineering, seismic, sediment) analyses before possible to significantly benefit isolated communities Figure 51 Hydropower Potential in the Ganges Basin 1,000 900 Hydropower Generation (MWh) 800 700 600 500 400 300 200 100 0 Kosi Chisapani Pancheswar Tehri Burhigandaki Sapta Gandaki Utyasu Andhi Khola Palamaneri Srinagar Tamur Seti1 Maneribheli Ranapratapsagar Kalagarh Gandhisagar Kota Maithan Kotli Behl Panchet Lower Arun Seti-6 west Rajghat Upper Trisuli Malatila Rihand Massanjore Kaligandaki II Karnali1B Kulekhani Kangshabati Base 3 Megadams All Dams Figure 52 Monthly Generated Hydropower (Based on Model Results) 500 450 400 Power Generation (MW-hr) 350 300 250 200 150 100 50 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Base Kosi High Dam Pancheshwar Dam Chisapani Dam All Dams 71 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks in project areas by enhancing connectivity of roads, objective for both is to store peak flows to achieve telecommunications, and power. steadier dry-season releases), and because flood control is limited, regardless of how operating rules Question 6. are designed. There is a tradeoff in the quantity of What is the Magnitude of Potential water used for irrigation in the Ganges plains versus Economic Benefits from Multipurpose Water low-flow augmentation in delta. Infrastructure, and What are the Tradeoffs Among Different Water uses? The potential economic benefits from new hydropower generation associated with Perceptions: Big gains, big tradeoffs developing the full suite of hydropower investments described in this report was There is a general sense that development of estimated to gross US$7–8 billion annually multipurpose infrastructure will bring significant (roughly US$5 billion net) above the current economic benefits, but no common perception about hydropower benefits produced in the basin (about the relative values of hydropower, flood control, and US$2.5 billion). This estimate assumes that 25 low-flow augmentation. percent of the power will be sold at peaking tariffs in India. If the energy from these dams were not used It is widely believed that the design and operation for peaking purposes, anticipated benefits would of multipurpose dams will significantly skew the be reduced by about 25 percent. Conversely, if the distribution of benefits among different water uses dams could be operated to supply greater than 25 (and hence users.) The tradeoffs are believed to be percent peaking power, the benefits would be higher. very large and, therefore, a matter of concern and Table 9 presents the economic optimization model contention. outcomes for various infrastructure options in an average year. Findings: Big gains, but modest tradeoffs While flood damages in the Ganges Basin are The gross economic benefits of additional significant, the report’s findings suggest that hydropower from the 23 new dam projects the construction of upstream multipurpose considered in this report were estimated to range water storage would not have a large effect from US$3–8 billion per year (depending on on flooding events. Impacts on peak flows in the infrastructure scenario and assuming that 25 the main-stem Ganges, particularly in wet years, percent could be sold as peaking power in India to would be relatively small. Thus, the economic yield an average power value of $0.1 per kilowatt value of flood savings associated with these hour). Since these 23 projects are estimated to cost infrastructure development options would be small about US$2 billion per year, the total net value of (Table 10). On the tributaries, and particularly in hydropower would likely be about US$5 billion the Gandak and Kosi Rivers, the reduction in peak per year. Benefits from additional irrigation and flows would be larger. But these major tributaries, ecosystems water are difficult to predict but in the on which the large dams would be built, are range of US$1–2.5 billion. extensively embanked. Along the Kosi, for example, embankments have never been overtopped by For the most part, the economic tradeoffs among floods. Flooding events on embanked tributaries hydropower, irrigation, and flood control objectives result more from embankment failures and localized are small. This is because there is little difference heavy monsoon rainfall that cannot be quickly in the optimal water releases for power production drained due to these embankments and the raised versus those for downstream water supply (since the river beds they have created. The evidence in this 72 Ten Fundamental Questions Table 9 Range of Economic Optimization Model Outcomes for Different Infrastructure Options Status Quo 3 Proposed 20 Proposed All Dams Mega dams Smaller Dams (Existing & Proposed) 1. Hydropower production (amounts above status quo shown in parentheses) a. Production (TW-hr/yr) 25.3 70.8 (+45.5) 51.7 (+26.4) 101 (+75.7) b. Value (billions of US$/yr) 2.5 7.1 (+4.6) 5.2 (+2.7) 10.1 (+7.6) 2. Low flows for irrigation (amounts above status quo shown in parentheses) a. Volume of water (BCM/yr) 83 111 (+28) 117 (+34) 121 (+38) b. Incremental value above status quo (billions of US$/yr) N/A +1.4 +1.7 +2.0 3. Low-flows augmentation in the delta a. Volume of water (BCM/yr) N/A +4.8 +9.0 +15.4 b. Incremental value above status quo N/A +0.24 +0.45 +0.77 (billions of US$/yr) 4. Change in monsoon season flows (%) a. Ganges at Farakka - -7 -8 -12 b. Kosi at Chatra - -7 - -14 c. Ghagara downstream of the Rapti inflow - -11 -6 -17 d. Gandak at India/Nepal border - -1 -22 -20 5. Infrastructure costs a. Capital cost (billions of $US) - 15.3 19.1 34.4 b. Annualized capital cost (billions of $US/yr) - 0.8 1.0 1.9 Note: Assumes that the marginal value of additional water in irrigation and that the marginal value of additional low flows to ecosystems in the delta are both US$0.05 per cubic meter. Calculations assume a 5 percent discount rate and 50-year time horizon. The values of low flows for irrigation and ecosystem services in the delta in the status quo are unknown and are listed as ‘N/A.’ report suggests that flood damages are unlikely to problems in the Ganges are in western Uttar be significantly reduced through the development Pradesh along the Ganga and Yamuna before of new, large-scale upstream infrastructures. Cost- these tributaries merge. By the time the Nepalese effective flood management will require a sharpened tributaries join the main stem of the river, water focus on forecasting and warning systems, and quality problems are less pronounced, so low-flow localized ‘hard’ (i.e., embankment management, augmentation of the tributaries does not solve the safe havens) and ‘soft’ (i.e., disaster preparedness, most dire upstream problems. insurance) responses. Agricultural and ecosystems values for With regard to water quality, as discussed augmented low flows are particularly difficult earlier, the construction of large storage to determine, as discussed in the economic structures in the Nepal Himalaya is unlikely optimization modeling section. On the one hand, to deliver much in the way of water quality evidence suggests that the current marginal benefits in India. The most serious water quality economic value of increased surface water for 73 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Table 10 Percent Reductions in Peak Flow in the Ganges Main-Stem and Major Tributaries Infrastructure Scenario Hydrology River +3 Mega dams + 20 Small Dams + All Dams Dry year Kosi 11 11 22 Ghagara 18 6 22 Gandak 1 27 27 Ganges main stem 6 8 11 Average year Kosi 7 7 14 Ghagara 11 6 17 Gandak 1 22 20 Ganges main stem 7 8 12 Wet year Kosi 6 6 9 Ghagara 11 8 15 Gandak 1 24 24 Ganges main stem 4 6 9 irrigation is quite low in India and Nepal.66 The Figure 53 irrigation water value used in the calculations Distribution of Economic Benefits from All presented in Table 9 (US$0.05) may overstate Proposed Large Dams current economic returns in agriculture. On the other hand, in the future, agricultural modernization and increased returns to water could change this picture dramatically. Similarly, it is difficult to place a value on dry-season water for ecosystems services, salinity control, and navigation. Although the essential value of water to communities in the delta is apparent, there has been no systematic measurement of that value. The current evidence is not sufficient to provide a robust estimate of the ecosystems value of water at the scale required for this report. Moreover, the value Hydropower that society places on ecosystems tends to rise with Irrigation incomes, and this is a rapidly developing economic Low flow for ecosystems region. Given the importance and sensitivity of assigning a value to water in any ecosystem, and in particular to an ecosystem as unique and fragile as the Sundarbans, this report concludes that those values remain to be substantiated. For simplicity, from development of all of the proposed large dams similar hypothetical values were placed on irrigation in the Nepal Himalaya would be roughly 74 percent and ecosystems water. Using these crude estimates, from hydropower, 19 percent from irrigation and 8 the distribution of incremental economic benefits percent from ecosystem services (Figure 53). 66 Chowdury 2005, Molden et al., 2001, Rogers et al., 1998, and Sharma et al., 2008. 74 Ten Fundamental Questions Recognizing the uncertainty of these values, Ganges delta, the important salinity-control functions various scenarios were modeled to explore nine of downstream flows, and navigation values. combinations of economic values for irrigation in Economic optimization in this scenario pushes Nepal and India (low-medium-high values) and 37 billion cubic meters of the additional water to low-flow augmentation (low-medium-high values) downstream low-flow augmentation in the delta, for ecosystems values in the delta (Table 11). Not with none allocated to irrigation. Total economic surprisingly, the resulting water allocations and benefits under this scenario are $11 billion, economic benefits of these two competing objectives 67 percent from hydropower, 33 percent from are sensitive to assumptions about the value of water low-flow augmentation. for irrigation in India and for low-flow augmentation in Bangladesh. Case 7 (lower left cell in Table 11) assumes that the value of irrigation water is several times higher than Case 1 (upper left cell in Table 11) illustrates a it is today, and that no value is attached to low-flow scenario in which irrigation water has very low value augmentation. This would be the case if significant (which the literature suggests is currently the case67) improvements were made in agricultural productivity and no value is assigned to low-flow augmentation in while no values were recognized for enhanced low the lower reaches of the Ganges system. In this case, flows in the delta. Of the additional low-flow water in the model calculates that it is economically optimal to this scenario, 28 billion cubic meters are allocated to allocate 38 billion cubic meters of the additional low irrigation while 5 billion cubic meters are allocated flow to irrigation, with just 6 billion cubic meters to to low-flow augmentation relative to the base case. low-flow augmentation in the delta. Total economic Total economic benefits under this scenario benefits under this scenario are $8.2 billion, are $11.7 billion, 67 percent hydropower and 95 percent derived from hydropower. 33 percent irrigation. Case 3 (upper right cell in Table 11) assumes Case 9 (lower right cell in Table 11) reflects a that the value of irrigation water remains small, but scenario in which irrigation values are high and that significant value is attached to downstream low-flow augmentation values are high as well. In flows in the delta–a value 10 times that associated this case, the model calculates that it is economically with low-productivity agriculture. This could be a optimal to allocate 38 billion cubic meters of the reasonable assumption, given the unique ecosystems additional low-flow to irrigation, and 19 billion cubic and associated biodiversity and tourism values of the meters to low-flow augmentation in the delta. Total Table 11 Irrigation and Low-Flow Outcomes for Different Water Assumptions with Full Infrastructure Development Value of Irrigation Outcome Value of Low-Flow Augmentation ($/m3) Water ($/m3) 0.00 0.05 0.10 0.01 Additional surface water irrigation (BCM/yr) 38 0 0 Additional low flow to Delta (BCM/yr) 6 35 37 0.05 Additional surface water irrigation (BCM/yr) 38 38 25 Additional low flow to Delta (BCM/yr) 5 16 25 0.10 Additional surface water irrigation (BCM/yr) 38 38 38 Additional low flow to Delta (BCM/yr) 5 16 19 67 Chowdhury 2005, Molden et al., 2001, Rogers et al., 1998. 75 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks economic benefits under this scenario are steady across all of these scenarios, varying $13 billion: 56 percent of economic benefits only about 6 percent. derive from hydropower, 29 percent from irrigation, and 14 percent from low-flow To illustrate how results can change depending on augmentation. the values assigned to additional irrigation water and enhanced low flows to the delta, the four cases These scenarios paint a fairly broad picture of the described above are presented in Figure 54. It possible economic futures of Ganges development. is clear that gains in agricultural productivity or Total economic benefits vary from $8 to 13 greater substantiated values in ecosystems services billion (gross) depending on the productivity of could change the distribution of benefits from large agriculture and the value assigned to low flows. The upstream reservoirs. In all cases, however, it should absolute value of hydropower remains fairly be noted that: Figure 54 Economic Benefits for Four Assumptions of Irrigation and Low-Flow Values Case 1: Value of new irrigation is low $0.01/m3 Case 3: Value of new irrigation is low $0.01/m3 Value of low flow in Bangladesh is low $0/m3 Value of low flow in Bangladesh is high $0.1/m3 $378 $3,646 Increasing Value of Irrigation $7,409 $7,841 Hydropower Hydropower Irrigation Irrigation Low Flow Low Flow Case 7: Value of new irrigation is high $0.1/m3 Case 9: Value of new irrigation is high $0.1/m3 Value of low flow in Bangladesh is low $0/m3 Value of low flow in Bangladesh is high $0.1/m3 $1,875 $3,833 $3,833 $7,388 $7,839 Hydropower Hydropower Irrigation Irrigation Low Flow Low Flow Increasing Value of Low Flows Note: Incremental economic benefits by type, for four combinations of economic values of additional irrigation (low-low, low-high, high-low, and high-high) in Nepal/ India and low flows in Bangladesh. 76 Ten Fundamental Questions • the majority of benefits will be generated from combinations of downstream economic values are hydropower and the absolute levels of these used across four infrastructure combinations. Panel benefits are not substantially diminished when the A depicts tradeoffs between hydropower production value of other uses increases, and and irrigation water. Varying the economic value • greater agricultural productivity, and of water used for irrigation changes the volume restoration of the Gorai, will only be achieved of water that the optimization model allocates to if complementary investments and reforms are irrigation, resulting in shifts along the x-axis under undertaken, and those investments and reforms each of the four infrastructure scenarios. Although should be of significant value even in the absence irrigation water usage varies significantly in Panel of upstream reservoirs. A for each of the scenarios, it is notable that power production does not vary greatly (i.e., there is Sensitivity analyses undertaken in this study provide new very little shift along the y-axis.) This means that information on the tradeoffs between operating water enhanced irrigation water use does not significantly infrastructure with the goals of maximizing hydropower, compromise power production: there is little tradeoff irrigation, flood control, and/or downstream low-flow between these upstream–downstream uses. Panel augmentation in the Ganges Basin. B illustrates tradeoffs between hydropower and low-flow augmentation for ecosystem services and There appears to be little tradeoff between navigation, and Panel C presents tradeoffs between hydropower production, on the one hand, hydropower and flood control. All three panels and downstream irrigation and/or low- exhibit similarly small tradeoffs between flow augmentation, on the other, because hydropower and downstream uses, across all four hydropower producers and all of the downstream infrastructure scenarios. users want the monsoon flood peaks to be smoothed and dry season flows increased. As shown in Figure There is, however, a tradeoff between the two 55 hydropower benefits decrease very little, by about downstream uses – irrigation water use in 5 percent, even when the economic value of water the plains and low-flow augmentation in the downstream is assumed to be $0.1 per square meter delta – because they are both consumptive (moving from Case 1 to Case 9.) This is because uses. If the economic value of low flows in the flood waters are stored behind hydropower dams delta is high, the economic optimization model during the flood season and released gradually over allocates less water for irrigation, and vice versa. the course of the year to generate power, which This is consistent with the results presented in Table enhances dry season flows and thus meets the 11. Even so, Figure 56 shows that increasing objectives of both water uses. The fact that there is infrastructure development can allow both surface little tradeoff between hydropower production and water irrigation and low-flow augmentation in the downstream water uses means that increases in delta to increase relative to the status quo. With full irrigation in the plains or low-flow augmentation in development, 40–60 billion cubic meters per year of the delta do not come at the expense of significant additional dry-season water would become available amounts of hydropower in upstream Nepal. that could be shared between these two competing Hydropower production is relatively insensitive uses. In reality, of course, actual use will be to changes in the economic value of water to determined not only by the relative economic values downstream users. of water to different users, but also by political, cultural, and social considerations. Figure 55 also illustrates the tradeoffs between hydropower production, on the one hand, and Finally, the economic optimization model downstream water uses, on the other. Nine was run to test the sensitivity of the results to 77 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 55 Tradeoffs between Water Uses 120 (Panel A) 120 (Panel C) Millions Millions 100 100 Hydropower production (MW-hr) Hydropower production (MW-hr) 80 80 60 60 40 40 All dams All dams Status Quo Status Quo 20 20 Mega Dams Mega Dams Small dams Small dams 0 0 80 90 100 110 120 130 30 35 40 45 50 55 60 65 Irrigation water used (bcm) Total flood overflows (bcm) 120 (Panel B) Millions 100 Hydropower production (MW-hr) 80 60 40 All dams Status Quo 20 Mega Dams Small dams 0 0 5 10 15 20 25 30 35 40 45 Low flow augmentation (bcm) Note: Tradeoffs between hydropower production and irrigation water usage (Panel A), low flow augmentation in the Delta (Panel B), and overbank flows during the flood season (Panel C) low- and high-flow years. When the Ganges percent for the three mega-dams, and a reduction optimization model was run with the hydrology for of 11 percent for full infrastructure development. wet and dry years, it was found that the incremental The reduction is lower if all dams are assumed to be value of hydropower produced by new infrastructure built because the dry years for individual tributaries would decrease with flows in the basin as expected. do not coincide, so building infrastructure in different This model run provides some sense of how climate rivers reduces the variability in (or spreads the risk change may affect the variability of the annual results. to) hydropower production that results from extremes A ‘typical’ dry year in the Ganges Basin corresponds in the most affected tributaries. Conversely, the to a reduction in additional hydropower of about 16 incremental value of dams to irrigation and low flows 78 Ten Fundamental Questions Figure 56 Question 7. Tradeoff between Irrigation Water Use and Low- What are the Cost- and Benefit- Sharing Flow Augmentation Dynamics of Upstream Water Storage 45 All dams Development? Status Quo 40 Mega Dams Perceptions: Big benefits upstream and Small dams 35 downstream Low flow in Bangladesh (bcm) 30 Perceptions differ by country, but it is generally 25 perceived that downstream countries will benefit greatly from upstream development and therefore 20 should share the costs of that development, perhaps 15 by sharing the initial capital costs. Some stakeholders believe that, in fact, the majority of benefits will 10 accrue downstream. 5 Findings: Big benefits, mostly in hydropower 0 80 85 90 95 100 105 110 115 120 125 If upstream multipurpose dams were built today, with Irrigation Water used (bcm) current low agricultural productivity and little flood benefit, this study finds that the overwhelming share of in the delta increases somewhat (by about 2 percent) economic benefits would be derived from hydropower. in a dry year because the water storage provides In the future, if agricultural productivity rises dramatically, higher incremental dry-season flows. Overall, the distribution of benefits could change. The principal incremental annual benefits would decrease by 8–10 unknown in this equation is the ecosystem and percent in a typical low-flow year. navigation values of enhanced low flows in the delta, which could be significant. The study’s findings suggest, In a wet year, hydropower production would not however, that the benefit-sharing calculus is simpler than change appreciably compared with an average previously assumed because downstream flood control year (increases by just over 1 percent with full and agricultural benefits are smaller than anticipated. development), because of the limited storage The benefits and costs to be shared at least in the near capacity in the dams in Nepal. The value of term will be predominantly associated with hydropower. the dams for providing irrigation and low-flow augmentation in such years also decreases The new information provided in this study has compared with an average year (by 8 and 17 implications for benefit and cost sharing in the percent for full development and three-dam development and financing of Himalayan dams. development options, respectively). Table 12 considers the following four possibilities: Table 12 Benefit Assumptions for Himalayan Dams Low-flow augmentation Low-flow augmentation augmentation to the to the delta delta is worth very little is worth a lot Increased dry-season water to Indian agriculture is worth very little Case A Case B Increased dry-season water to Indian agriculture is worth a lot Case C Case D 79 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Case A assumes low values for both irrigation Case B is more complicated. If low-flow water and low flows/environmental flows. Case B augmentation to the delta is valuable,69 those assumes that irrigation water is not valuable, but economic benefits can be added to the hydropower that environmental flows are. Case C assumes that benefits because there are low tradeoffs between irrigation water is very valuable, significantly more the two uses. In Case B, Bangladesh, India, productive than it is today, but that environmental and Nepal all gain from the construction of the flows have little worth. Case D sees quite high values Himalayan dams. Nepal and India share the benefits from both uses. of hydropower generation (assuming the excess power produced in Nepal is exported to India), and It is unclear which scenario reflects current Bangladesh benefits from the low-flow augmentation circumstances. The literature suggests that surface (increased environmental flows).70 water supplies to Indian agriculture are worth very little in economic terms, around $0.01 per cubic Under this scenario, Bangladesh and India should meter.68 They may even have negative value if both be willing to share in the costs of building applied to waterlogged areas. With regard to the the Himalayan dams: Bangladesh should invest value of low-flow augmentation in the delta, the for the low-flow augmentation and India should literature tells us very little. Given the ecology and invest as part of a power trade agreement with biodiversity of the delta and the dependence of delta irrigation co-benefits. The magnitude of each populations on navigation, however, we must assume country’s contribution would depend largely on the there is appreciable value to low-flow augmentation current values of power, irrigation, and low-flow in the downstream reaches of the river. augmentation. Although this study has provided very broad indications of the relative magnitudes of these Although many stakeholders believe the values, the negotiations for benefit and cost sharing basin is described by Case D, the findings of of any specific project would require extensive, joint this study suggest that Cases A and B better analysis of costs and benefits. describe the Ganges today. Furthermore, the distribution of costs and benefits Consider Case A. This is a simple story: the under this scenario would be affected by the level of economic benefits from the Himalayan dams are water withdrawals in India. The water systems model simply hydropower and perhaps some Nepalese assumes that Indian withdrawals would be made to irrigation. There are few downstream economic the full capacity of its current infrastructure. Even with consequences for India or Bangladesh. One this assumption, low flows could be doubled in the implication of this case is that the benefit-sharing driest months if the Himalayan dams were built. In calculus between Nepal and India for hydropower contrast, the economic optimization model, allocates development is, in fact, much simpler than previously water where its value is highest. This means that if assumed – Himalayan dams produce hydropower low-flow augmentation in the delta is more valuable benefits almost exclusively (95 percent). If this is than irrigation, the additional low flows would be the case, India and Nepal should not delay in allowed to pass through India to Bangladesh. The negotiating straightforward power development and values presented in Figure 54 Figure 56 which trade agreements. were derived from the economic optimization 68 Chowdury 2005, Molden et al., 2001, Rogers et al., 1998, and Sharma et al., 2008. 69 The authors believe there are very important values to low-flow augmentation in the delta. Due to the lack of quantitative research, however, specific values have not been included in this report. 70 The water systems models assume that Indian off-takes would increase to their full channel capacity, until no more water could be drawn from the system with existing infrastructure. These benefits could be even higher if Indian off-takes did not increase. 80 Ten Fundamental Questions model, therefore, assume that India would allow the and that basinwide flood-protection benefits are increased low flows to pass through to Bangladesh. likely to be negligible. India might do so if: • as this study suggests, groundwater is, in fact, a An immediate benefit-sharing opportunity better option than increased surface water flows for the region that is not explored in these for supplementing dry-season irrigation, scenarios is cooperative investment in regional • increased environmental flows were desirable hydrometeorological data collection and within India, or information management, coupled with forecasting • the benefits of regional cooperation were and warning systems. compelling. Question 8. Assurances regarding flow abstractions in the plains, Is Large Infrastructure the Best Strategy for and an agreed valuation of low-flow augmentation, Protecting Communities from Floods? would be two key challenges in negotiating a benefit-sharing agreement. Perception: Yes Building infrastructure is the most effective and Case C is worth a comment. If the unit values for reliable way to protect communities from flooding. irrigation water are high, the economic optimization model allocates Nepal 10–12 billion cubic meters Findings: Not everywhere, and not exclusively for new irrigated agriculture. This withdrawal is substantial, and it would be for new, not existing, There is no simple solution to floods. In some areas irrigated areas in Nepal – although it could involve of the world, a focus on large infrastructure (dams hydropower tradeoffs. Given the poor availability of and embankments) has been fairly effective. In the spatially specific data on agricultural productivity in highly variable monsoon-driven Ganges system, with the basin, the economic optimization model assumes its thousands of tributaries, these solutions are not as that the value of water in agriculture to India and effective. To protect communities in the Ganges Basin Nepal is the same. If irrigation values are high, and a shift in focus is needed from flood control to flood differentiated among countries, the economically management; marked by a greater emphasis on optimal distribution of enhanced low flows among regional forecast and warning systems, embankment all three riparians could change. asset management, drainage, and, importantly, more localized ‘soft’ responses including disaster Case D reflects the current mindset of most preparedness, land zoning, safe havens, insurance, stakeholders. It is widely assumed that irrigation and training and communications campaigns. Flood water and low-flow augmentation is extremely protection for basin communities and their livelihoods valuable to Bangladesh and India. Many believe that requires a broad, balanced combination of ‘hard’ irrigation water is extremely valuable, particularly in and ‘soft,’ local and transboundary responses. India, and that flood control from upstream dams is extremely valuable for the whole system. The limited Floods are not new to the Ganges Basin, and local empirical evidence reviewed in this assessment, populations have been coping with the challenges however, suggests that irrigation has very low of periodic inundations for centuries. Accounts productivity, such that the benefits from low-flow from as early as the 12th and 13th centuries71 augmentation to Indian agriculture would currently record methods of adaptation to the ferocious and be quite small (though this could change over time) unpredictable monsoon flooding in the plains, but 71 Mishra 2008. 81 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks also highlight the benefits of floods.72 By the late 19th However, the longer-term impacts of these century, floods were generally seen as something embankment systems have been mixed, to be controlled, and large-scale infrastructure and mounting criticism is challenging the was seen as the best means to achieve this goal.73 paradigm of such structural investments Embankment systems and barrages were built in to control flooding. Some authors point to the an attempt to control water flows for irrigation and fact that embankment systems have altered the to contain floods. These were conceived with an hydrological characteristics of the basin77 because expectation that a large water storage infrastructure high silt loads, typically deposited in the plains areas would someday be built far upstream in the during flooding, are carried further downstream, Himalaya, which, along with the embankment raising river beds, exacerbating drainage and systems, would provide full control of floods.74 congestion, and, ultimately, increasing the risk of catastrophic flooding from embankment failure. In This analysis makes clear that the expectation that Bangladesh, it was found that embankments not only upstream storage can fully control floods across the increase siltation in the river beds and floodplains basin is untenable. The emphasis should now shift but also raise flood water levels, which, in turn, from the idea of ‘controlling’ floods to the idea of increase the water velocity.78 As Figure 57 shows, ‘managing’ floods through better management and much of the flooding today in Bangladesh is actually maintenance of the existing embankment systems due to waterlogging and drainage congestion, complemented by nonstructural investments, for rather than riverine flooding. This type of flooding, example, in forecasting, zoning, insurance, temporary because it stays on the land longer, can be more relocations, flood-friendly architecture, and changes harmful in the long run to agricultural production.79 in cropping patterns, described later in this section. When embankments fail, it can be Embankments remain the most pervasive catastrophic. Embankment breaches or failures— flood control technology in the Ganges like the devastating Kosi embankment breach Basin.75 Embankment systems gained prominence of 2008—bring on sudden severe flooding that under British rule in India. It is interesting to note,76 catches communities off guard. At the same time, however, that, despite the public popularity of the embankments lead communities to believe that they idea of flood control, there was significant debate are not at risk of flood. This false sense of security among both British and Indian engineers as early as manifests in a lack of preparedness, it reduces social the turn of the last century as to whether these systems awareness of risk and encourages behaviors such as were viable in the monsoonal, silt-laden Ganges settlements in historic flood plains, thereby actually Basin. That debate continues in the region today. increasing vulnerability.80 Embankment management is essential. Regardless of upstream development, Embankments do provide short-term and asset management systems for embankment localized benefit to agricultural land, lives, monitoring and maintenance are an imperative for and property that face chronic flooding. protecting communities in the Ganges Basin. 72 Bandyopadhyay 2009 and Verghese 1990. 73 Bandyopadhyay 2009. 74 Mishra 2008. 75 Embankments, sometimes called levees, are continuous earth bunds on one or both sides of a river constructed to protect surrounding lands from inundation. 76 See Mishra 2008 for an interesting account of the early debate over embankments along the Ganges. 77 Moench and Dixit 2007. 78 Hossain and Zakai 2008. 79 Planning Commission of India 1981. 80 Dixit 2009, Moench and Dixit 2007, and Bandyopadhyay 2009. 82 Ten Fundamental Questions Figure 57 Flood Typology of Southwestern Bangladesh Water logging Riverine flooding Tidal Flooding Source: Rashid (2009). High population (Table 13) growth in the basin and that big cities find it increasingly difficult to cope has exacerbated the problem of flooding. Over with rising flood waters and dense populations. the years, flood plains have been taken over by human settlements, and traditional flood detention Flooding disproportionately affects poor and areas have been converted to residential areas. The socially vulnerable populations in the basin. spreading of concrete and paving in these settled The poor and socially marginalized typically live areas have left the land with less capacity to absorb with higher risks of exposure to flooding. These rainwater resulting in increased runoff into the rivers, populations also have less access to institutions and especially in growing urban centers. Large-scale services. Poor communication and transportation felling of forests has also left land vulnerable to networks make many communities difficult to access erosion and increased runoff. A 2007 report by the during and after flooding, and many localized floods World Health Organization noted that urban flooding may not register on the state or national scale so is a growing problem in cities in the Ganges Basin, those communities may not be classified as in need 83 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Table 13 lag in or lack of relief to reach the poor means, in Decadal Population Growth Rate Estimates turn, that those most vulnerable populations face the greatest difficulty in recovering from shocks and Country/State Decadal Population Growth Rate Estimate disaster events. (2001-2011) Bangladesha 14.7 The poor also have more limited income opportunities and fewer assets, which make Nepalb 25.4 them more vulnerable to extreme poverty and Indiac 17.6 Bihard 25.1 destitution.83 Many of the households surveyed in Chattisgarh 22.6 Bihar take loans from local moneylenders to rebuild Delhi 21.0 their homes and to purchase inputs for agriculture Haryana 19.9 or livestock.84 In the post-flood period, many Himachal Pradesh 12.8 respondents said that rates increased from 5 percent Jharkhand 22.3 Madhya Pradesh 20.3 per month to 10 percent per month for a loan, Rajasthan 21.4 creating difficulties in repayment and undermining Uttar Pradesh 20.1 their recovery. Uttarakhand 19.2 West Bengal 13.9 Women face particular challenges from Note: a Estimated 2001-2011 decadal growth rate as per the 2001 Bangladesh Census; b Estimated 2001-2011 decadal growth rate as per the 2001 Nepal diminished water quality and agricultural Census; c Average population growth rate for India 2001-2011, preliminary productivity. Research from the Sundarbans area of results of the 2011 India Census; d State-wide decadal growth rates for India 2001-2011, preliminary results of the 2011 India Census. Bangladesh has shown that increasing contamination of drinking wells and lower agricultural production has placed disproportionate pressure on women. of relief. Social prejudice against the poor and lower Because women typically collect water for drinking castes may also impact the way in which relief is and domestic uses, less water availability means distributed. For example, during the 2008 floods in they travel further distances to complete this task. India, reports emerged that relief supplies in Bihar Interviews with women have shown that they have were going to the highest castes first81 and that adjusted by drinking less water during the day to lower castes were often the last to be rescued.82 This conserve the number of trips needed to fetch water.85 “During floods, those who have cattle take “[In the floods of 2007]… we lost them to higher places and feed them with everything, our livestock, livelihood, and dry fodder. Also, many people sell them our houses were damaged. I don’t think we at lower prices. The person who is buying have recovered yet… at this point I think [them] bargains and takes animals at much we won’t recover.” lower prices. Many businessmen come to – Female respondent, Muzzafarpur District, Bihar, buy these cattle during floods… We can’t India, July 2010 pawn animals but yes we pawn our jewelry.” – Female respondent, Khagaria District, Bihar, India 81 Ramesh 2007. 82 Rabinowitz 2008. 83 Maxwell Stamp 2010, chapter 4, note 48. 84 Focus Group Discussion, Madhubani District, Bihar, India 85 Ahmad forthcoming. 84 Ten Fundamental Questions Also, lower agricultural production caused by saline Although well-managed embankments intrusion has resulted in greater food insecurity for cannot control flooding, they can form part women because the intra-household allocation of of a larger flood management solution in food often disadvantages women and young girls.86 the Ganges Basin. Decades of investments in embankment systems have created localized It is clear that to protect basin communities, and short-term benefits for many of the basin’s and in particular the poor and socially populations who rely on these buffers to protect vulnerable, current strategies are inadequate. their land, assets, and livelihoods. In addition, Much of the current literature shows that while elevated embankments are also often the first point embankments continue to be the preferred flood- of evacuation for flood-affected populations, who control intervention in the Ganges Basin, they have rely on them for refuge and to await relief. Over failed to solve the problem of excessive flooding the longer term, embankments can have significant during the rainy season.87 Moreover, the illusion social and environmental consequences, so their of security provided by embankments often means management and maintenance require a fresh look. that softer measures, such as early warning systems, Still, maximizing the current embankment systems’ preparedness and disaster response have been benefits by improving maintenance, drainage, and overlooked; there is little systematic response to silt removal is essential for protecting communities disastrous events. and key assets. The findings of this report confirm the Information, forecast and warning limitations of large infrastructure strategies systems are clearly a priority. As experience for flood control in the basin, and point in Bangladesh has shown, community-based to the need for a shift in focus from flood preparedness and early-warning systems can control to flood management. Rather than trying contribute significantly to reduced loss of life and to control floods, complementary nonstructural property caused by cyclones. A reliable, real-time flood management interventions are needed to hydrometeorological monitoring system (ideally manage them. Flood management has been on a regional scale to track the movement of increasingly advocated in recent years by a range the monsoon) will be fundamental to managing of basin opinion makers. Nonstructural, or ‘soft’ floods in the region. Technical innovations in data interventions, are not new to the Ganges Basin. gathering (satellite and land-based), information Indigenous settlement patterns and architecture in management, modeling and forecasting protocols, the Indian floodplains show elevated housing built and communications technologies have dramatically on bamboo posts, excavated ponds serve water use increased the potential of these systems to quickly needs but also act as flood buffers, and strategies and economically provide life-saving warnings to of high mobility during flood seasons through the communities. Additional benefits of these investments use of boats and seasonal movements to higher could be timely agrometeorological information to grounds.88 Many of these measures are still used help farmers time their planting, fertilization, and today by people living in flood-prone areas of the harvesting, and the collection and management of basin. Box 4 shows that a strategy of nonstructural information for monitoring of and adaptation to management of floods can be effective. climate change. 86 ibid. 87 Ahmad Ahmad 1992 and Dixit 2009. 88 Bandyopadhyay 2009. 85 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Box 4 Are Embankments a Good Flood-Control Strategy? A Case Study of the Kosi River On August 18, 2008, the Kosi River breached its embankment in Nepal close to the Bihar border. The Kosi’s westward loop was cut off, flooding a vast, roughly triangular area with the apex of the triangle at the breach site and the base of the triangle 150 kilometers to the south. According to official sources, 493 people were killed and some 3,500 reported missing after the disaster. In all, 3.3 million people in Bihar were affected and, at the peak of the flood, 440,000 were living in camps. In February and March 2009, a survey was conducted of 10 flood-affected villages in Bihar. Eight were flooded by the Kosi after it breached the embankment (‘unexpectedly flooded villages’). The other two, located near the Ganga and the Kosi, are flooded annually during the monsoon by their respective rivers, thus they are adapted to flooding. In fact, both of these villages have most of their fields inside an embankment. The following year, in April and May 2010, the researchers resurveyed the 10 villages. They also surveyed eight more villages for comparison. Some of these additional villages were regularly flooded; others were not regularly flooded by river overflow, nor were they unexpectedly flooded due to the embankment breach (‘control villages’). The researchers compared these three types of villages – unexpectedly flooded, regularly flooded, and not flooded – over the period July 2008 to March 2010. Their objective was to see whether a strategy of allowing floods but building dispersed infrastructure to cope with them would be better than the current government strategy of flood protection based on embankments. The study found that, in fact, the regularly-flooded villages were, on average, no worse off than the control villages. The most striking finding was that the gross value of crop output in the regularly flooded villages was the same or higher than that in the control villages, despite the fact that three out of four of the regularly-flooded villages in the sample are located inside embankments, and, therefore, are highly exposed to seasonal and concentrated river flooding. The second major finding was that mean wages of agricultural and casual workers were no lower in the regularly-flooded villages than in the controls. Third, these regularly-flooded villages do no worse on measures of schooling, health, wealth, and household amenities. There was one big difference between the regularly-flooded villages and the controls: in the regularly- flooded villages, agricultural output varied much more sharply over the year, which caused dips in the proportion of households getting sufficient food during the monsoon. These results suggest that a strategy of gradually moving away from reliance on embankments and instead building infrastructure to live with floods would (1) not result in a net loss of agricultural or other output or health indicators (2) save money currently going into embankment maintenance, and (3) prevent the apparently inevitable disasters that occur every few years when there is a major embankment breach. The infrastructure to replace embankments, apart from obvious measures like raising buildings on stilts and digging new channels for river flow, should include the social infrastructure of employment generation or other social and food security during the monsoon for areas that will face increased flooding. Source: Adapted from E. Somanathan 2011. Based on surveys undertaken by E. and Rohini Somanathan. 86 Ten Fundamental Questions Other ‘soft’ interventions could include Figure 58 large-scale flood-plain management, disaster Sedimentation in an Irrigation Canal in Uttar Pradesh preparedness, land-use planning, modification of cropping patterns, flood zoning, raising of villages and/or safe havens, insurance, microfinance, and education and communications campaigns.89 Flood protection for basin communities and their livelihoods requires a broad, balanced combination of ‘hard’ and ‘soft,’ local and transboundary responses. Question 9. Is it Possible to Control Sediment in the Ganges? Perception: Yes Source: Nagaraja Harshadeep Rao (2010). Watershed management and upstream storage can control sediment loads. it affects the morphology of the river, the floodplains, and the delta. About 95 percent of Findings: Not Really the sediment load is delivered during the monsoon, The high altitude and steep terrain of the sediment so sediment loads are extremely sensitive to source regions, as well as the nature of the sediment unpredictable and highly variable flood flows. These and the ongoing tectonic processes, make it variations influence the erosion and deposition impossible to undertake the scale of watershed dynamics of the river, for example at existing bridge management interventions that would be necessary areas, river training works, and the intake points for to have any measurable impact on basinwide irrigation schemes. They also affect navigation and sediment yields. drainage by changing the level of the river bed, and decrease flows to distributaries as sedimentation The volume of sediment is so large that capturing it clogs irrigation offtakes (Figure 58.) behind large dams would be extremely costly; the reservoirs of these large, expensive structures would A particular challenge posed by sediment in fill quickly and thereafter produce very few benefits. the Ganges is the dynamics of high sediment loads in embanked stretches of the river. The As shown earlier (Table 1) the Ganges is one of Kosi, which is largely embanked and estimated to the most sediment-laden rivers in the world, carrying carry more than 100 million tonnes of sediment every more suspended sediment than the next three most year, is a good example. A substantial quantity of sediment-laden rivers combined. The Ganges- the highly variable sediment gets deposited within Brahmaputra system carries about 2.9 million tonnes the Kosi’s embankments, raising the river bed above of silt daily. the level of the surrounding land in some stretches, causing the river to move to possibly more dangerous The high level of sediment transport in the courses within the embankments, and enabling even Ganges system is of great concern because low flows of water to come close to embankment 89 WHO 2007, Moench and Dixit 2007, and National Committee on the Development of Backward Areas 1981. 87 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 59 Schematic of Embankments in Sediment-Laden Rivers River Cross Section Without Embankments Populations either have temporary settlements near the flood plain, reducing the risk or choose to settle away from the flood plain. Without embankments, water rises over a larger area during floods. Sediment builds up over time but stays constant beyond a certain point. River Cross Section With Embankments Embankments need continuous Populations settle close to maintenance to avoid breaches, embankments assuming they are safe, especially if they are poorly constructed. in fact they are at increased risk to If sediment build up is significant, they breaches and overtopping may need to be raised indefinitely Water logging often occurs outside Sediment rapidly builds up within the confines of the embankments even after rivers embankment, raising water levels within the recede if drainage is inadequate. embankment above the level of the surrounding land. capacity (Figure 59). The Yellow River in China, amount of sediment entering the system, and (2) which, along with the Amazon, has silt loads infrastructure designed to capture and regulate comparable to the Ganges, is a striking example of sediment once it is in the system. The volume of this phenomenon. The Yellow River’s embankments sediment in the Ganges is so extreme that have trapped so much silt that at some locations the capturing sediment in large infrastructure river bed is six meters higher than the surrounding would not be economic; these large expensive landscape. Rivers, of course, are supposed to be the structures would simply fill up too quickly. lowest points in the landscape to facilitate drainage Any infrastructure developed in the Ganges system of both river and rain water. In the case of the Kosi, will need sophisticated systems for flushing sediment sediment build-up has rendered other embankment downstream.90 defenses, such as drainage gates, inoperable because they have become buried under the sediment. To assess the potential for watershed management to control sediment in the Ganges, it is necessary Both the volume and the source of sediment to identify the geographic sources of the sediment. in the Ganges make it extremely difficult Figure 60 shows that the vast majority of sediment to manage. There are two general strategies for in the Ganges Basin comes from the High Himalaya managing sediment in a river system: (1) watershed (3,000–8,848 meters), and, to some extent, management to stabilize soils and diminish the from the Lesser Himalaya or Mahabharat Range 90 Significant advances have been made in sediment flushing techniques, China’s Three Gorges Dam is a notable in this regard. 88 Ten Fundamental Questions Figure 60 Sediment Flow in the Ganges-Brahmaputra System (million tonnes per year) Ganges Basin Brahmaputra Basin Source Regions Tethyan Himalaya <10% High Himalaya 80% + 10% Lesser Himalaya 20% + 10% 729 590 794 480 Siwaliks <10% Plains <10% Peninsular <10% Ganges Farakkah Bangladesh 1,000 450 65 328 550 Subaqueous Delta Floodplains Hooghly Floodplains & Sinks Delta plains 95 Bengal Fan Source: Prepared by IWM based on data from Wasson 2003. (2,000–3,000 meters). The altitude and terrain crippling water stress as well as more severe and of the sediment source regions, as well as more frequent droughts and floods. the nature of the sediment and the ongoing tectonic processes, make it impossible Findings: Uncertainties are great, but to undertake the scale of watershed immediate actions can be taken management interventions that would be Climate change uncertainties in South Asia and the necessary to have any measurable impact Ganges Basin, in particular, are extreme, but the on basin sediment yields. Nepal, in particular, range of mean basin runoff predictions is roughly has an impressive history of community forestry comparable to the recent historical record and the management, with strong results in terms of local basin’s highly variable climate today. Moreover, erosion management and livelihood benefits. These even the most extreme scenarios do not change the activities, however, are predominantly undertaken basic findings and recommendations of this report. in the Siwaliks or Churia Hills at elevations of just A focus on managing current hydrological variability 600–1,200 meters above sea level, far below the is, therefore, a good place to start in addressing the main sediment source regions. future climate change challenges of the Ganges. Question 10. Climate Change in the Ganges Basin What will Climate Change Mean for the Basin? Everywhere, climate change presents uncertainties. Perceptions: Enormous change But in South Asia these uncertainties are compounded by a profound lack of data and the Many fear that the Himalayan glaciers will melt inability thus far to construct a credible methodology and change the Ganges River from a perennial for modeling predictions of how monsoon patterns to a seasonally flowing river, and that changing might change, in particular with regard to the temperatures and precipitation patterns will create relationship between climate and hydrology. Added 89 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks to the complexity of the massive monsoon system Temperature in the basin will rise. The extent is the diversity of microclimates in a region where of the temperature rise will depend on the level altitudes can range almost 8,800 meters across a of coordinated global actions to mitigate carbon distance of 200 kilometers. releases into the atmosphere. All climate models are in accord that the Ganges Basin will experience The Fourth Intergovernmental Panel on Climate significantly increased warming. Mean annual Change (IPCC) report91 left a ‘white spot’ over South temperature at the country level is projected to Asia and the greater Himalayan region suggesting increase 1.2 – 1.5 °C (A2 scenario)92 by mid-century that data were insufficient to support credible and 2.8 – 3.9 °C (A1B scenario)93 to 3.5 – 4.8 °C analysis It is one of several key regions having (A2 scenario) by 2100. As shown in Figure 61, the greatly divergent predictions of future changes in GCMs agree that temperatures will increase, though precipitation. A new generation of global circulation they disagree on the level and spatial distribution of models is being developed and efforts are underway change. to downscale existing models to a regional basis in South Asia. But none of this information is yet Evaporation losses in the Ganges system available, leaving tremendous uncertainty in any will increase, as will system water demands. discussion of South Asian, and Ganges-specific, Increased temperatures expected under climate climate futures. change scenarios will result in increased evapotranspiration losses from catchments and This study estimated temperature, rainfall, and runoff increased evaporation from reservoirs and streams. for the Ganges Basin using all of the 16 United Crop water requirements will increase substantially Nations Framework Convention on Climate Change as temperatures increase. Other changes (e.g. (UNFCCC)-recognized Global Circulation Models increased cooling requirements) will also put (GCMs). Although there appears to be a clear pressure on water systems. trend toward increasing temperatures, predictions regarding rainfall and runoff vary widely and point Glacier melt rates will increase. A study done to the possibilities of either increasing or decreasing as input to this report94 indicated that glacier melt water availability. The range of model results contributes only about 4 percent of the Ganges underscores their uncertainty, and their predictions annual flow (see Figure 62.) Melting occurs can mask extremes, but the results do suggest that mostly during the high-flow season in the Ganges. the scale and focus of today’s climate challenges In contrast to Europe and North America, where – unpredictable and intense rainfall, alternating glacier melt contributes to low summer flows, the extremes of flood and drought – will continue to be Himalayan glaciers melt during the monsoon season the key climate challenges in the coming decades. when temperatures are highest but rainfall is also A focus on managing current hydrological variability heaviest. Thus, while changes in glacier melt will be (whether or not it is attributable to climate change) a fundamental challenge for some melt-dependent is, therefore, a good place to start in addressing the mountain communities, it is not a major driver of future climate change challenges of the Ganges. basinwide hydrology. 91 IPPC 2007. 92 ‘The A2 storyline and scenario family describes a very heterogeneous world. The underlying theme is self-reliance and preservation of local identities. Fertility patterns across regions converge very slowly, which results in continuously increasing global population. Economic development is primarily regionally oriented and per capita economic growth and technological change are more fragmented and slower than in other storylines.’ (IPCC Special Report Emissions Scenarios. IPCC, 2000) 93 The A1 storyline is a case of rapid and successful economic development, in which regional average income per capita converge - current distinctions between ‘poor’ and ‘rich’ countries eventually dissolve. The A1B scenario assumes a balance across energy sources. (IPCC Special Report Emissions Scenarios. IPCC, 2000) 94 Alford and Armstrong 2010. 90 vTen Fundamental Questions Figure 61 Temperature Predictions for the Ganges Basin for 16 GCMs Ganges - Differences between GCMs, in terms of Change in Temperature, by the 2050s CM3 CGCM3.1-T47 BCM2.0 MK3.0 (CNRM) (CCMA) (BCCR) (CSIRO) Change in Temperature (Degrees Celsius) > +4 CM2 CM2.1 GISS-ER CM3.0 + 3.5 (gfdl) (GFDL) (INM) +3 +2.5 +2 CM4 MIROC3.2- ECHO-G ECHAM5 (IPSL) Medres (MUIB) (MPI) +1.5 +1 This map shows the temperature change projected by the considered climate model, under the A2 scenario CGCM2.3 CCSM3 PCM1 HADCM3 for 2040 - 2069 as compared to 1961 (MRI) (NCAR) (NCAR) (UKMO) - 1990. Map displays gridded data (cell size=0.5dd). Source: WCRP’s CMIP3 (Meehl et al. 2007), downscaled by Maurer et al. (2008). Disclaimer: The boundaries, colors, denominations, and other information shown in any map do not imply any judgment on the part of the World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Melt is likely to increase in the future. For Although changes in glacial area (e.g. the well- example, the zero-degree isotherm (the steady- publicized retreats of some glacier ‘tongues’) state equilibrium line altitude, where total annual are apparent in aerial photographs and high- accumulation equals total annual ablation and resolution satellite images (Figure 63), they can be the glacier net balance is zero) could move in the misleading. Although a glacier might retreat at its summer from its current height of about 5,400 terminus, it could still be growing in mass. It is the meters to about 6,100 meters by the end of the mass and volume of the glacier that is relevant for century. This movement would increase melting in water storage and supply, but the changes in glacier many glaciers, but it would still leave almost half mass or volume are much harder to measure that Nepal’s Himalayan glaciers above the the reduction in the tongues. Given the complexity new isotherm. of glacial dynamics, the response of glaciers to 91 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 62 Share of Glacier Melt in Nepal’s Himalayan Rivers 16000 14000 Streamflow (MCM) 12000 10000 8000 6000 4000 2000 0 1 2 3 4 5 6 7 8 9 Basin 14149 7765 5624 6672 5192 6929 4153 2091 9510 4-6 km 3119 2197 1682 2669 1007 2130 828 247 2194 Glacier Melt 418 421 1248 878 482 496 160 52 484 Source: Alford, et al., 2010. Note: Relative streamflow, in million cubic meters per year, of: (green) glacier melt, (red) 4000-6000 meter altitudinal belt, and (blue) basin total, for glacierized gauged basins in the Nepal Himalaya. Basins are: 1. Bheri, 2. Kali Gandaki, 3. Budhi Gandaki, 4. Marsyangdi, 5. Trisuli, 6. Dudh Kosi, 7. Tama Kosi, 8. Likkhu, 9. Tamor. variations in temperature and precipitation are not to the deposition of rock and debris carried by well known. Further complicating these analyses the glacier. As these lakes grow, water pressure are recent concerns about the acceleration role of builds behind the natural dams, which can burst, aerosols and the Asia Brown Cloud (a persistent threatening communities and infrastructure layer of air pollution over the South Asia region). downstream. There are currently some twenty glacial Field-based glacier measurements are sparse in the lakes in Nepal that are considered GLOF risks.95 High Himalaya. However, it seems clear that glacial Figure 63 melt under climate change will not be important in Rapidly Growing Glacier Lake the Ganges from a regional hydrologic perspective. The Ganges system as a whole is unlikely to be significantly affected by glacier melt, but melting glaciers will have serious local impacts. Communities living in some glaciated sub-basins, for example, could face dramatic changes in water availability. In the Nepal Himalaya, the annual contribution of glacier ice melt to total river volumes varies among the nine catchment basins from 2 to 30 percent. Similarly, glacier melt increases the risk of glacial lake outburst floods (GLOFs.) Natural dams (moraines) form when glaciers retreat/melt, due Source: ICIMOD (2011). ICIMOD photo. 95 ICIMOD 2010. 92 Ten Fundamental Questions Figure 64 Water Balance and Snowmelt Contribution in Himalayan Basins WATER BALANCE AVERAGE (1969 - 2001) PER MAJOR BASIN Prec: Precipitation (BCM), Etr: Real Evapotranspiration (BCM), SW: Soil Water Content change (BCM), Surq: Surface run off (BCM), Groq: Return flow (BCM), Perc: Water into vadose zone (BCM, and Ssnw: Snow melt (BCM) Sub-Basins Atrai Betwa Chambal Gandak Ganga Ghaghra Gomati Gorai Hoodly Ken Kosi Mahananda Sindh Son Tons Yamuna Source: Derived from the Ganges SBA SWAT model, using IPCC climate scenarios (from INRM). Snow accumulation and melting regimes could contributes about 30 billion cubic meters annually to change. A critical change in the basin hydrology the 500 billion cubic meters of flows. could result from changes in snow. Given that temperatures during the monsoons are expected to be Sea level will rise. The delta regions of the warmer and the zero-degree isotherm is expected to Ganges Basin are very flat and fertile, and very rise to a higher altitude, some of the precipitation that vulnerable to sea-level rise. Significant inundation today falls as snow will become rain, resulting in lower and salinity intrusion are predicted. As illustrated snow accumulation and higher runoff. Consequently, in Figure 65, a predicted one-meter rise in sea during the spring thaw, there will be less snow to level would inundate 2,062 square kilometers (1.5 melt, resulting in lower water flow in the pre-monsoon percent of the country and affect 1.52 million people low-flow season. This could have a significant impact (1.12 percent of the population.) A significant in some catchments where snowmelt is a major increase in storm surges is also predicted to input. Figure 64 indicates that snowmelt currently accompany the one-meter rise in sea level. 93 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Figure 65 Predicted Sea-Level Rise and Storm Surges in Bangladesh Future storm surge zone Current storm surge zone Other coastal zone < 10m International boundaries Capital city Cities Source: Based on analysis carried out by the World Bank (2010), major lakes and rivers (RWDBII, CIA 2006), populated places (GRUMP, CIESIN, Columbia University, IFPRI, the World Bank, and CIAT, 2004). Data sources: sea storm surge (World Bank, 2010) major lakes and rivers (RWDBII, CIA 2006), populated places (GRUMP, CIESIN, Columbia University, IFPRI, the World Bank, and CIAT, 2004). 94 Ten Fundamental Questions It is interesting to note, however, that even Enduring Uncertainties Surrounding with sea-level rise, it is unclear whether the delta Climate Change in the Ganges will suffer a net loss in land area. Sediment Precipitation projections are particularly loads are so high in the Ganges-Brahmaputra- unclear. Figure 67 presents basin precipitation Meghna delta that in recent years land has been predictions by the different Global Climate Models, steadily accreting (forming). The recent rough all for the same (A2) climate scenario. Results diverge balance between erosion and accretion is presented enormously, underscoring how difficult it is to draw in Figure 66. conclusions about precipitation change in the basin. Figure 66 Erosion and Accretion along the Bangladesh Coast Source: European Space Agency (2010). 95 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks There is no consensus among climate models Runoff could change, but how? Changes in the even as to the sign of the projected changes spatial and temporal distribution of precipitation in rainfall for the Ganges Basin. Some of the and temperature interact in complex ways to scenarios indicate very high rainfall in the Himalaya determine both ‘green’ water (the water used/lost (i.e., 80 percent increase in precipitation) whereas in catchments before it reaches rivers) and ‘blue’ others indicate just the opposite (i.e., 80 percent water (the runoff that reaches rivers). Green water decrease in precipitation). Such divergent, yet tends to impact rainfed agriculture and rangeland ‘equally likely,’ GCM scenarios make it difficult to livestock, whereas blue water affects the reliability justify any specific models as representative. of surface water systems for irrigation, hydropower, Figure 67 Precipitation Projections for the Ganges Basin from 16 GCMs Ganges - Differences between GCMs, in terms of Change in Precipitation, by the 2050s Change in Precipitation (%) <-50 CM3 CGCM3.1-T47 BCM2.0 MK3.0 -50 - -40 -40 - -35 (CNRM) (CCMA) (BCCR) (CSIRO) -35 - -30 -30 - -27.5 -27.5 - -25 -25 - -22.5 -22.5 - -20 -20 - 17.5 -17.5 - -15 -15 - 12.5 -12.5 - -10 -10 - -7.5 -7.5 - -5 -5 - -2.5 CM2 CM2.1 GISS-ER CM3.0 -2.5 - 0 (gfdl) (GFDL) (INM) 0 - 2.5 2.5 - 5 5 - 7.5 7.5 - 10 10 - 12.5 12.5 - 15 15 - 17.5 17.5 - 20 20 - 22.5 22.5 - 25 25 - 27.5 27.5 - 30 30 - 35 35 - 40 CM4 MIROC3.2- ECHO-G ECHAM5 40 - 50 (IPSL) Medres (MUIB) (MPI) 50 - 75 75 - 100 100 - 150 > 150 No Data CGCM2.3 CCSM3 PCM1 HADCM3 (MRI) (NCAR) (NCAR) (UKMO) This map shows the precipitation change projected by the considered climate model, under the A2 scenario for 2040 - 2069 as compared to 1961 - 1990. Map displays gridded data (cell size=0.5dd). Source: WCRP’s CMIP3 (Meehl et al. 2007), downscaled by Maurer et al. (2008). Disclaimer: The boundaries, colors, denominations, and other information shown in any map do not imply any judgment on the part of the World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Note: Divergent results are highlighted (boxed) for illustrative purposes. 96 bulk water supply, and environmental flows. Runoff flows, and that the inter-annual variability around the could change substantially (or not) in the basin – but range of projected mean changes could potentially the magnitude, or even direction, of the change create major new challenges for populations in is not easy to assess given the wide variations in the basin. When the temperature and precipitation precipitation changes. There is little agreement on outputs of the IPCC Global Circulation Models the range of runoff predictions generated by the 16 were fed into the SWAT model used in this study, we GCMs under an A2 scenario (Figure 68). obtained a wide range of runoff scenarios on both sides of the current baseline, as shown in Figure The changes in mean flows projected by the suite 69: Predicted and Historical Monthly Runoff in the of GCMs represent average changes that are not Ganges Basin. This broad variability points to the outside the natural variability in the system. But it need for robust, flexible water management systems must be emphasized that these are changes in mean that can predict and respond to both wet and dry Figure 68 Runoff Predictions for the Ganges Basin from 16 GCMs Changes in Water Yield (%) -40 - -35 -35 - -30 -30 - -27.5 -27.5 - -25 -25 - -22.5 CM3 CGCM3.1-T47 BCM2.0 MK3.0 -22.5 - -20 (CNRM) (CCMA) (BCCR) (CSIRO) -20 - -17.5 -17.5 - -15 -15 - -12.5 -12.5 - -10 -10 - -7.5 -7.5 - -5 -5 - -2.5 -2.5 - 0 0 - 2.5 2.5 - 5 5 - 7.5 7.5 - 10 CM2 CM2.1 GISS-ER CM3.0 10 - 12.5 (gfdl) (GFDL) (INM) 12.5 - 15 15 - 17.5 17.5 - 20 20 - 22.5 22.5 - 25 25 - 27.5 27.5 - 30 30 - 35 35 - 40 40 - 50 50 - 75 CM4 MIROC3.2- ECHO-G ECHAM5 (IPSL) Medres (MUIB) (MPI) CGCM2.3 CCSM3 PCM1 HADCM3 (MRI) (NCAR) (NCAR) (UKMO) This map shows the precipitation change in water yield (wy) by the considered wy of the GCMs model, under the A2 scenario for 2040 - 2069 as compared to the baseline 1961 - 2001. Map displays gridded data (cell size=0.5dd). Sources: WCRP’S CMIP3 (Meehl et al., 2007), downscaled by the World Bank (2011) Disclaimer: The boundaries, colors, denominations, and other information shown in any map do not imply any judgment on the part of the World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Note: Divergent results are highlighted (boxed) for illustrative purposes. 97 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks extremes. As the climate models for this part of the broad population and economic growth, increasing world improve, there may be more convergence of nonagricultural water demands, increasing results, but currently, the historical variability, the ecosystems values.) This means that a ‘predict-then- temperature signal, and the range of precipitation act’ framework for managing climate uncertainty, and runoff scenarios are all that is available to work which is often considered the first best approach for with in improving climate risk management. incorporating climate change into adaptation and development planning, cannot and should not All this uncertainty leaves water planners in a be followed. difficult position as they must carefully weigh what information in the climate change domain they can Where credible predictions cannot be made, as this reliably use, and what they cannot. In reality, water report finds to be the case in the Ganges Basin, managers in the Ganges Basin are struggling to the best option is to assess the sensitivities of policy manage today’s climate variability. It is difficult to choices and recommendations to the uncertain adapt to the degree of hydrologic variability that range of climate futures. That is the approach we already exists, let alone the additional variability adopt here. that climate change could bring. Focusing on the urgent requirement of managing today’s The findings and recommendations of this report are therefore examined against extreme scenarios variability, however, will strengthen the to determine whether there are potential ‘tipping region’s ability to cope with climate change in points’ at which the recommendations might prove the future. counterproductive maladaptations. Where great uncertainty exists, emphasis should be placed on Robust Recommendations in a flexible approaches that can accommodate adaptive Changing Climate management as more information becomes Policy decisions must be (and are being) made in available, approaches that both perform well over a the context of unresolved uncertainty. It is essential, wide range of potential conditions, and those therefore, to acknowledge these uncertainties and that deliver immediate benefits regardless of design recommendations that are generally robust to climate change.96 climate. The recommendations of this study appear robust in Do we know enough to act? Yes. all of these regards. Even the most extreme climate change scenarios are not anticipated to change the In the Ganges Basin the most critical uncertainty is basic findings of this report. hydrology, more specifically, predictions regarding the timing and volume of rainfall and runoff. A focus on large-scale infrastructure for flood Because these predictions are so varied across a control, and on surface water for irrigation, range of credible models, it is impossible to define could prove susceptible to climate change. It is a ‘most likely’ future for which policies could be conceivable that there might be extreme hydrological targeted. Moreover, even if water availability could changes that could diminish the usefulness of be predicted, water demand is changing rapidly reservoirs for flood control, for example if they were in the region due to both climate (i.e., increasing consistently overtopped or unfilled. With regard evapotranspiration) and non-climate drivers (i.e., to irrigation, extreme combinations of rainfall and 96 Dessai and Wilby 2010–2011. 98 Ten Fundamental Questions Figure 69 Predicted (a) and Historical (b) Flow Rates at Farakka on the Ganges Predicted (a) 250 200 150 Flow (m3/s) 100 50 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Historical (b) 300 250 200 Flow (m3/s) 150 100 50 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Source: INRM (2011). Note: Predictions of monthly mean runoff (flows) in 2050 are presented for the 16 UNFCCC GCMs, alongside the historical monthly average flows for the years 1969- 2001. Measured at Farakka Barrage near the India-Bangladesh border. 99 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks temperatures (which drive evaporation and crop millions of people routinely suffer from flood, water needs) might undermine the function of drought, and crop failure due to unpredictable surface-water irrigation schemes. rains. The Ganges is one of the most disaster-prone regions of the world, in addition to being one of the In contrast, the recommendations of this study are most vulnerable to changes in climate. A focus on likely to become more valuable under greater climate strengthening capacities to manage current climate extremes. With regard to flood management, for variability will deliver immediate benefits to people– example, this study finds that storage capacities in the especially the poor and vulnerable–throughout the system are simply inadequate to make large-scale Ganges Basin while strengthening the knowledge infrastructure-focused flood management a viable and institutions needed to manage future changes. strategy on a basinwide scale. Changing hydrology cannot improve the small ratio of available storage to At the heart of this report’s recommendations is a annual flow rates that limit water managers’ capacity to focus on information and institutions, in particular in hold back flood peaks. In fact, the evidence suggests regards to flood management and conjunctive use that annual rainfall could increase, making storage of water resources. Moreover an early investment capacities even less adequate for regulating flows. in climate information will support future climate change research and model development. These The report suggests that a shift in focus toward types of interventions are far more flexible and enhanced forecast and warning systems in concert adaptive than large-scale, long-lived infrastructure. with a suite of tailored, localized responses is, The risk of maladaptation is therefore quite low. therefore, urgently needed. Greater climate extremes, variability and uncertainty only strengthen Priorities for Future Climate Research the logic of this recommendation. Similarly, the A great deal of research on climate change is need and potential for enhanced conjunctive use underway and no doubt the people of the basin will of surface and groundwater only becomes more benefit from this work. Of urgent importance to the compelling as temperatures and hence evaporation basin, however, are some specific challenges: rates increase, and the timing of surface flows • Climate to hydrology modeling of the South Asian become even less predictable. Monsoon • The significance of rainfall intensity in the basin This report’s recommendations also remain robust • Enhancement and sharing of the basic when considered in terms of their immediate benefits hydrometeorological data and flexibility looking forward. In the basin today, • Greater understanding of glacier dynamics 100 5. Findings, Implications, and Opportunities Findings to enhance the productivity and sustainability of the river and, at the same time, safeguard lives and This report highlights the complexity of the Ganges Basin and clearly indicates the need to revisit livelihoods. Systematic collection and exchange of commonly held perceptions about the basin’s appropriate, modern water, weather and climate resources and future development path. Storage in data; cooperative efforts in advanced modeling, the Himalaya, long seen as the preferred strategy for forecasting and communications, and warning managing the region’s devastating floods, appears systems; and a shared information base for basin untenable as an exclusive basinwide solution. planning will help the countries seize the basin’s opportunities and manage its risks. The pieces Hydropower potential, on the other hand, remains as are all in place. There is tremendous expertise in promising as ever – with the benefit-sharing calculus the region. Bangladesh boasts world-class water appearing much simpler because downstream modeling institutions and cutting-edge flood benefits and tradeoffs among different water uses warning systems. India’s long experience in water are smaller than previously assumed. Low flows can engineering is now coupled with burgeoning satellite be meaningfully augmented by the development and information technologies sectors, essential of upstream storage, but the immediate economic for modern hydrometeorology. Nepal, with its benefits are surprisingly unclear. Moreover, wealth of water resources, sets an excellent global groundwater utilization could offer the same storage example for information sharing by making real-time benefits much more rapidly and at lower cost (but hydrological data available online. Moreover, all not the hydropower generation associated with three countries are involved in or planning significant Himalayan storage). investments in hydromet monitoring systems, systems that could be made interoperable for basinwide Although climate change remains an area of great information management. Cooperation could take uncertainty, the basic findings of this report are many forms, from a network of national institutions robust to the range of anticipated futures. A strategy with an agreed information sharing protocol, to a to cope with existing climate variability by investing dedicated multilateral institution that would gather, in strengthened information and institutions at analyze and then disseminate crucial hydromet and the regional level, along with a range of tailored climate data. A strengthened real-time regional interventions at the national and local levels, would hydromet information system (eventually in the public be a no-regrets path that should enhance productivity domain with open data infrastructure to facilitate its and resilience in the Ganges Basin today and the use) would provide the scientific information needed capacity to manage climate change in the future. by planners to sustainably manage and develop the basin; by farmers to enhance productivity and food Regional cooperation in information security; by disaster risk-management professionals management to safeguard lives and assets; and by climate researchers to understand, predict and adapt to The Basin holds clear and immediate opportunities the changing – but also immediately challenging – for regional cooperation in information management climate in the Ganges Basin. 101 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Hydropower development and trade costly undertaking, and this report suggests that storage investments would not be economically Immediate opportunities are also apparent for justifiable solely – or even significantly – on hydropower development and trade. There is the grounds of their immediate contribution to significant untapped potential in the basin and a enhancing agricultural productivity in the basin. In steadily growing demand for clean energy. Moreover fact, there are large areas of seasonally waterlogged the benefit-sharing calculus appears simpler than land whose productivity could potentially be commonly believed for several reasons. First, the diminished if more water were applied during the tradeoffs among different water uses are modest. dry season, a time that usually allows for recovery. Infrastructure would be designed and operated Upstream storage alone will not modernize much the same way whether the goal was to agriculture in the Basin. A range of interventions maximize hydropower, or to maximize flood and are needed (and are underway in some areas) to irrigation benefits downstream. Negotiations over the enhance agricultural productivity and support the design and operation of multipurpose infrastructure livelihoods of poor farmers, interventions anticipated with transboundary impacts should, therefore, be to be effective regardless of the development of tractable. Second, the current economic value of upstream storage. downstream irrigation benefits is surprisingly small in comparison to hydropower benefits, due to low Enhanced low-season flows may hold important agricultural productivity. At least in the near term, potential to sustain ecosystem services, particularly the direct economic benefits of these upstream in the fragile Sundarbans (mangrove forests) of the reservoirs would derive overwhelmingly from Ganges delta. Yet the ecosystem values of increased hydropower. Co-benefits for agriculture should be low-flows downstream—while possibly quite high— amenable to transparent negotiations. Third, flood remain unsubstantiated. Even if upstream reservoirs benefits (if any) are confined to tributaries. Upstream were built and low-flows were raised, key areas storage will have negligible basinwide flood impact. like the Gorai in southwestern Bangladesh would Benefit sharing with regard to flood protection not be restored without additional investments and could therefore be appropriately negotiated at institutional arrangements to dredge key intakes the tributary scale (i.e., between two countries), (investments like these might be adequate to restore rather than basinwide. Benefit sharing with regard the Gorai in the absence of upstream reservoirs.) A to the enhancement of low flows for irrigation and final important unknown is the value of augmented ecosystems, conversely, remains an appropriate low flows in combating saline intrusion in the delta, issue for basinwide discussions. Finally, the models and the importance of the Ganges freshwater plume developed in this report provide a new set of third- for the dynamics of currents and storm patterns in party tools that could be used to help quantify the Bay of Bengal. More study of the morphology impacts and support information-based negotiations and ecosystems values in the Ganges delta is on hydropower development. urgently needed. Enhancing low-flow season water availability A promising alternative to upstream water storage reservoirs is the potential to augment low-season The basin also holds promising possibilities for flows by increasing groundwater use in conjunction enhancing low-season water availability. Low flows with well-managed surface water schemes. In can be significantly augmented (potentially doubled eastern Uttar Pradesh and Bihar, groundwater could in the dry months) as a co-benefit of developing produce effective storage (and hence augment dry- multipurpose storage reservoirs upstream. But the season water supplies) on a scale comparable to the development of upstream storage reservoirs is a Himalayan dams, but much more rapidly, at lower 102 Findings, Implications, and Opportunities cost, and at the national or local scale. If upstream Implications and Immediate Opportunities multipurpose dams are found to be economically, If many of the commonly held perceptions of the socially, and environmentally justified by the bundle basin are incorrect, what are the real opportunities of benefits they can produce (predominantly for sound, cooperative action? hydropower), additional dry-season water could prove to be an important co-benefit, perhaps as Cooperative Basinwide Information a complement to more immediate interventions in Management conjunctive use. Implications: Fragmented and inaccessible Flood management information can sustain broad misperceptions Still the basin faces persistent challenges, particularly • The scale and complexity of the Ganges in managing floods. Large dams built to hold back system, and the extremes of its landscape, flood waters high in the Himalaya have long been require systematic study using modern data and seen as the preferred strategy for managing the modeling techniques. region’s devastating floods. But as an exclusive strategy, it is untenable. The physical storage volume • The development of this first basinwide model available in the mountains is simply too small to suggests that on several critical issues, broadly have a meaningful impact on basinwide floods. held perceptions are at odds with the evidence. Flood management is needed, flood control is not possible. Effective flood management will call for Opportunities: A cooperative regional information regional information and warning systems, coupled system is needed with a range of hard and soft, national and local investments. • Systematic collection and exchange of appropriate, modern water, weather, and climate Finally, significant climate change uncertainties data; cooperative efforts in advanced modeling, remain in the basin. Current data and models give forecasting, communications and warning systems; and a shared public-domain hydromet little compelling evidence of what the future holds. information management system are immediate It appears that mean hydrological variability in the opportunities. future will be similar to the pronounced variability seen in the basin today, but extremes may well be • A strengthened basinwide knowledge base would greater and could potentially create major new provide the scientific information needed by challenges for populations in the basin. planners to sustain and develop the basin; by farmers to enhance productivity and food security; Climate change by disaster professionals to safeguard lives and assets; and by climate researchers to understand, Greater climate extremes, however, would predict and adapt to the changing climate as well only strengthen the justification for the basic as the current challenging weather systems in the recommendations of this report. Investing in Ganges Basin. cooperative information management, modeling • An inclusive river committee or commission and forecasting systems at the regional level, along could develop a shared knowledge base and with a range of tailored interventions at the national operational model of the basin, establish norms and local levels, would enhance productivity and and protocols for transparency and information resilience in the Ganges Basin today, as well as the sharing, and identify and pursue opportunities for capacity to manage climate change in the future. cooperative development projects. 103 Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks Hydropower Development and Trade and energy-pricing environment in conjunction with a well-managed surface water system. Implications: Hydropower potential is significant, and • In the Gaghra Gompti Basin (Uttar Pradesh), should be simpler to negotiate than previously thought for example, 2.5 million new tubewells could be • Because downstream benefits and tradeoffs sustained. among water uses are currently smaller than • A conjunctive-use strategy could also help assumed (due to low agricultural productivity and manage waterlogging in the basin, and enhance waterlogging) the benefit-sharing calculus should the reliability of water supplies to tail-end users be simpler than previously thought. in surface irrigation schemes and/or eastern • Over time, if agricultural productivity increases downstream irrigators. and ecosystem uses are better understood, the bundle of benefits that could be derived from Flood Management multipurpose dam development could grow substantially. Implications: Infrastructure alone is not the answer • The challenges of managing social and ecological • Upstream storage infrastructure cannot protect impacts, sediment loads, and seismic risks remain. the basin from flooding. • Strategies must shift to flood management Opportunities: Power development and trade are because flood control is not possible. possible • Flood management calls for a range of ‘hard’ • Significant potential exists to deliver clean peak- and ‘soft’ investments that might include: load power and improve trade imbalances. – Data Data collection, information • Potential also exists for upstream storage-backed management, and knowledge sharing hydropower that could be fairly traded among the – Warning and forecast systems, inundation and basin countries to the benefit of all. risk mapping – Asset management systems for embankment Improve Water Delivery Through monitoring and maintenance Groundwater Development – Disaster preparedness including safe havens and escape routes, designated inundation Implications: Look for water storage underground, areas, insurance schemes, and land zoning not just upstream – Re-engineering of drainage, housing, water • Groundwater storage in Uttar Pradesh alone supply and sanitation, etc. could provide as much storage as upstream dams – Awareness and community mobilization in Nepal. campaigns. • Groundwater storage is the quickest and • Institutions and networks will be needed to probably the lowest-cost way to create system implement and sustain these efforts. storage and improve water delivery efficiency. Opportunities: Develop regional information; Opportunities: Make sustainable, strategic, forecast and warning systems; and national/local conjunctive use of significant additional groundwater flood management including: resources • A basinwide hydromet information system • Significant untapped groundwater resources exist designed to collect and manage the information in the central and lower reaches of the basin. needed for protection (disasters) and productivity • Immediate opportunities exist to increase strategic (agrometeorological) today, and climate use of groundwater, within an appropriate policy change tomorrow. 104 Findings, Implications, and Opportunities • A basinwide forecasting capacity and disaster infrastructure, labor and land tenure issues, among warning system that includes regional forecasts other issues. Climate change will likely bring a and a system to communicate warnings to new dimension to the challenges already facing national institutions for action. agriculture. The issue of agricultural productivity is • Regional platforms for information sharing, receiving attention from both committed researchers research, collaboration, and shared learning on and policy makers, notably India’s National Planning flood management and climate adaptation in the Commission. Efforts to enhance productivity, whether Ganges Basin. through focus on the augmentation of surface and • National and local flood management measures, groundwater supplies or the host of other challenges as above. faced by farmers in the Ganges, are priorities both for farmers’ livelihoods and for food security in this Key Issues for Future Research rapidly growing region. This report begs many questions. Based on the evidence the study produced, and, importantly, on Climate change in the basin and the region the evidence that could not be found or produced in Climate change is an area of priority research this limited effort, several priority areas for additional globally, but it is particularly pressing in the information emerge. Ganges. Vulnerability of the basin, by virtually any measure, is extreme. At the same time, uncertainties Ecosystems values of water in the Ganges delta are pronounced. Modeling efforts have been Water is the lifeblood of ecosystems, nowhere more unsuccessful in predicting changes in the South so than in delta ecosystems like the Sundarbans. Asian monsoon, and the range of microclimates in Although the essential value of water to communities this basin – which runs from the summit of Mount in the delta is apparent, there has been no Everest to the sea – further frustrates these efforts. systematic measurement of that value. The current The vast, dense, dynamic population of the basin, evidence is not sufficient to provide a robust and its extreme vulnerability to climate change, give estimate of the ecosystems value of water at the good reason for a sustained regional research effort. scale required for this report. Moreover, the value A cooperative regional effort in climate research that society places on ecosystems tends to rise with could be particularly valuable. incomes, and this is a rapidly developing economic region. Given the importance and sensitivity of Looking Forward assigning a value to water in any ecosystem, This report is intended to encourage research and particularly to an ecosystem as unique and fragile as debate on the fundamental strategic questions of the Sundarbans, the conclusion of this report is that the Ganges Basin. In doing so, it has challenged those values remain to be substantiated. 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SAWI is a multi-donor trust fund managed by the World Bank on behalf of the governments of United Kingdom, Australia and Norway and supports activities related to the management of the Greater Himalayas transboundary water systems in Afghanistan, Bangladesh, Bhutan, China, India, Nepal and Pakistan. SAWI’s program is built around the theme of knowledge, dialogue, cooperation; the region’s three shared river basins – the Brahmaputra, Ganges and Indus rivers; and the Sundarbans landscape.