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The Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized

Overview Report No. 67668-SAS

The Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks

Overview

The Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks

World Bank South Asia Regional Report

World Bank Washington, DC

iii THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

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1 2 3 4 14 13 12 11

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Cover design: Roots Advertising, Gurgaon, India iv Acknowledgments

The Ganges Strategic Basin Assessment is a product contributions from the Nepal Himalayas. Michael of an extensive collaborative effort among many Westphal analyzed historical climate and climate professionals within and outside the World Bank. It change scenarios for the basin. The Center for is an output of the South Asia Water Initiative (SAWI), Environmental and Geographic Information Services which is a partnership of the World Bank and the (CEGIS) in Dhaka, the International Centre for governments of Australia, Norway, and the United Integrated Mountain Development (ICIMOD) in Kingdom that seeks to facilitate regional cooperation Kathmandu, and the International Water Resources in the sustainable use and management of the water Management Institute (IWMI) in India and Nepal resources of the Himalayan Rivers. provided the 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. Sanjay Pahuja, R.S. Pathak, Anil Pokhrel, Giovanna Prennushi, Martin Rama, Shyam Ranjitkar, Catherine Specific inputs to this study were provided by a Revels, Bharat Sharma, Mandira Shrestha, Animesh broad range of experts and institutions. In particular, Shrivastava, Ranu Sinha, Ashok Subramanian, the Institute for Water Management (IWM) in Dhaka Catherine Tovey, Rajib Upadhya, George Verghese, developed the calibrated Ganges Basin model Winston Yu and William Young. Individuals too and worked closely with the World Bank team in numerous to name provided extremely useful analyzing the implications of major future scenarios. insights at consultation meetings held with a variety IWM’s work was led by Bushra Nishat and Asif of government and donor partner agencies, and Zaman with guidance from Mahbub-ur-Rahman research, policy, and academic institutions in and Emaduddin Ahmed. INRM Ltd. (Integrated Bangladesh, India and Nepal. Natural Resource Management Consultants) in Delhi developed the calibrated SWAT model for The team benefitted from the advice of a broad the Ganges Basin under the leadership of Ashwin range of colleagues. It wishes to express its Gosain (Indian Institute of Technology, Delhi), R. appreciation for the guidance and support of Srinivasan (Texas A&M University) and Sandhya colleagues within the World Bank including Rao. RMSI Pvt. Ltd., Delhi, supported work on flood Kalpana Kochhar, Roberto Zagha, Susan and drought analysis. E. Somanathan, of the Indian Goldmark, Ellen Goldstein, Jack Stein, Salman Statistical Institute, undertook an investigation of the Zaheer, Rachid Benmessaoud, Gajanand economics of “hard” versus “soft” flood mitigation Pathmanathan, Herbert Acquay, Karin Kemper, and strategies. Don Alford, Richard Armstrong, Julia Bucknall. A special thanks to Ngozi Okonjo- and Adina Racoviteanu estimated glacier melt Iweala and Isabel Guerrero for their guidance in

1 THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

key consultations. The team is also grateful to have Howard, Russell Rollason and Clare Shakya, also received input from two advisory groups outside provided insightful and substantive support to the the Bank: an international Expert Advisory Group, team. comprising David Grey, Glenn Jenkins, Mark New, and Peter Rogers; and the Abu Dhabi Dialogue The team gratefully acknowledges support Group of regional experts. The SAWI development from the SAWI and the World Bank South Asia partners (the Governments of Australia, Norway Regional Integration Unit, and sincerely thanks all and the United Kingdom), in particular Bente Binge, of the individuals and institutions met during the Simon Buckley, John Dore, Semund Haukland, Guy development of this work.

2 Overview

Background All countries in the basin benefit from the Ganges and suffer from its extremes; all could benefit The Ganges River Basin—the world’s most populous more and suffer less from the devastating floods river basin—stretches from the highest mountains and periodic droughts which routinely undermine in the world to the tidal delta of Bangladesh. The development in the region. This study explores Ganges River rises in the Himalayan border regions development opportunities in the basin – for of China, Nepal, and India, and runs 2,500 example in hydropower, irrigation and disaster risk kilometers across the Indian subcontinent to the management – against a backdrop of extreme mangrove forests of the Sundarbans, finally emptying climate uncertainty, rapid population economic into the Bay of Bengal. The basin encompasses growth and urbanization. a multitude of glaciers, thousands of tributaries, vast plains and an extensive, fragile delta. The The Ganges Strategic Basin Assessment amazing variety of ecosystems in the Ganges River Basin provides homes for the subcontinent’s wealth The objective of the Ganges Strategic Basin of flora and fauna, many of them under stress or Assessment (Ganges SBA) is to build knowledge and endangered. promote an open, informed dialogue on the shared opportunities and risks of cooperative management The Ganges watershed is a complex interplay of in the basin. Advances in remote sensing, intense monsoon rains and runoff, glacier and hydrological modeling and forecasting capabilities, snow melt, and groundwater resources. The unique and open access data platforms now make an geography of the region creates this interplay: unprecedented wealth of information available to summer clouds drift up from the Indian Ocean all. These advances offer the basin countries an and the Bay of Bengal, laden with moisture; are opportunity to ‘leap frog’ the technologies and trapped by the high Himalaya; then rain down on methods they use to gather, manage, analyze, and the Gangetic plain. Most precipitation in the Ganges share information. The Ganges SBA identifies River Basin is concentrated into only a few months ways in which information can be generated and each year. Because of dramatic seasonal monsoons used to strengthen planning and decision making and high climate variability, much of the region is in the Ganges Basin, and seek evidence-based routinely affected by flood and drought. opportunities for mutually beneficial cooperation.

The daily lives of 655 million inhabitants depend on The Ganges SBA highlights the complexity of the the water that the Ganges and its tributaries provide Ganges basin and demonstrates an urgent need for drinking, agriculture, hydropower generation, for a shared understanding of the full basin system. navigation and ecosystem services across more than The system is so large and complex that it simply one million square kilometers. These inhabitants cannot be fully understood intuitively. Commonly include some of the poorest people in the world— held perceptions are reexamined using modern data more than 70 percent of whom live on less than $2 sources and modeling techniques to come to fact- per day. Population density in the basin averages based understandings about the basin’s resources 600 people per square kilometer, more than ten and possible future development paths. The study’s times the global average. For governments in results challenge some long-held beliefs about the this region, the combination of extreme poverty Ganges River Basin suggesting that some of what and complex water management issues creates has long been considered “common knowledge” is, tremendous challenges. in fact, inaccurate.

THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

25°N 30°N

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B B Kishangarh Sagar Gandhi Ratlam 200 km Bhilwara 75°E 100 150 RAJASTHAN 100 50 Udaipur 50 PAKISTAN 0 0 This map was produced by the Map Design Unit of The World Bank. The boundaries, colors, denominations and any other information shown on this map do not imply, the part of The World Bank Group, any judgment on the legal status of territory, or endorsement or acceptance of such boundaries.

25°N

30°N The Ganges River Basin

4 The study provides particularly valuable insights hydrological data available online. Moreover, all relating to flood control, irrigation and hydropower: three countries are involved in or planning significant investments in hydromet monitoring systems— • Flood control. The findings of this study refute systems that could contribute to a basinwide the broadly held belief that upstream water knowledge base. storage (i.e. reservoirs) in Nepal can effectively control basinwide flooding. Currently, most development in the basin is through • Irrigation. The study indicates that storage incremental, project-by-project activities within reservoirs in Nepal could potentially double low each of the riparian countries. There has been flows downstream in the dry months. Yet the value surprisingly little systematic regional research on of this additional water is surprisingly unclear, the basin’s development options and challenges and similar storage volumes could be attained using modern analytical tools that go beyond through better groundwater management. sector, country, or state analysis to examine the • Hydropower. The study confirms that larger strategic questions that the basin faces. In hydropower development and trade hold addition, perceptions of current conditions and real promise (subject to rigorous project level future development paths in the Ganges basin vary assessment with particular attention to sediment dramatically within and among different stakeholder and seismic risks). In the near to medium term, groups, institutions, and countries. there appear to be less significant tradeoffs than expected among different water uses. Until now, there has been no basinwide knowledge base and analytical framework that could be used Complexity arises from the fact that many of these by riparian states to explore options and facilitate benefits potentially relate to the development of cooperative planning in the Ganges river basin. The multipurpose reservoirs. Determining the right Ganges SBA begins to fill a crucial knowledge gap, configuration, sequencing and scale of interventions providing an initial integrated systems perspective is therefore quite challenging. on the major water resources planning issues facing the basin today, and on some of the most important Most immediately, however, the report points to infrastructure options that have been proposed for significant opportunities for regional cooperation in future development. flood-related information and forecasting systems. Infrastructure alone cannot protect the people of the Information and data are surprisingly scarce and Ganges Basin from floods. Information and warning difficult to obtain. In particular, very little information systems will be an enduring priority. Given the is available on hydrology and irrigation withdrawals regionwide scale of the South Asian monsoons, a in India. Significant efforts were made to assemble systematic, regional approach is called for to collect the data sets used in this analysis, drawing on and exchange water, weather, and climate data, publicly available data in Bangladesh, India, and and to advance efforts in modernizing modeling, Nepal, and on global data sets. The effort was forecasting, and communications and warning undertaken by a World Bank team in cooperation systems. with several leading regional research institutions and involved repeated exchanges with policy makers The pieces are all in place. There is tremendous and opinion makers in the basin. expertise in the region. Bangladesh has expert water modeling institutions and innovative flood A set of reliable hydrological and economic warning systems. India’s long experience in water models for the Ganges system has been engineering is now coupled with burgeoning satellite developed and tested. These models are believed and information technologies sectors, essential adequate for assessing the impact of existing and for modernizing hydrometeorology. Nepal, with its new hydraulic structures on flooding, hydropower, wealth of water resources, sets an excellent global low flows, water quality, and irrigation supplies example for information sharing by making real time at the basin scale. We emphasize that this

5 THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

report focuses only on basin-level dynamics; is generally assumed that this potential could be any specific projects under consideration would harnessed through large multipurpose dams to still require full economic, environmental, and produce hydropower, deliver more timely irrigation social assessments with specific attention to water, and regulate the extreme flows of the Ganges local ecological, seismic, and cultural contexts. River. This study found that the potential reservoir Significant uncertainties—including climate storage volume in the Nepal Himalaya is surprisingly change—persist and better data would allow low relative to the flow of the river. the models to be further refined. But the basic conclusions based on the model results are robust Although many reservoir sites in the Himalaya are and have been used to develop strategic insights. attractive for the development of multipurpose water storage infrastructure, the steep terrain A key feature of this regional research is the and mountain gorges mean that surprisingly little development of a set of nested hydrological and water can be stored behind even very high dams. economic basin models, along with targeted Developing all 23 of the large dam sites that analyses on social vulnerability and climate change. have been identified in Nepal (including the Kosi, The three major components of this work included: Chisapani and Pancheswar dams) would provide additional active storage equivalent to only about 18 • Water systems modeling and analysis to examine percent of the basin’s average annual flow. This is the physical dynamics of the Ganges Basin, very little storage on a basinwide scale. including: surface water system, water balance, irrigation use, water quality, climate change If every one of these large dam sites were implications, floods and glacier melt. developed, the aggregate active storage on the • Economic optimization modeling and analysis to river system (including storage in Bangladesh, India explore: economic tradeoffs, the distribution of and Nepal) would only reach 130–145 billion benefits from combinations of new development cubic meters. This amount of storage is quite small projects in the basin, and the economic benefits of compared with the 500 billion-cubic-meter average additional low flows and flood mitigation strategies. annual flow of the Ganges River and the 1,200 • Social analysis through literature review, focus billion-cubic-meter average annual rainfall within the group discussions, and key informant interviews Basin. This additional storage would allow for some to understand the social impacts of and responses redistribution of flows within a year, but it would not to water variability. allow for any significant storage across years (see Figure 2). As a point of comparison, man-made The mosaic of information produced with these tools storage capacity on many major rivers such as the and approaches was used to examine alternative Colorado, Murray-Darling and Nile Rivers, is 100– scenarios across a range of possible Ganges futures, 200 percent of the mean annual flow, a volume that and to address some pressing development questions. allows for multiyear storage operations.

Ten Crucial Questions These dams would also be very costly; the 23 large infrastructures examined would require capital The Ganges SBA study focused on ten fundamental investment of roughly US$35 billion (2010 dollars) questions. and likely take decades to construct. The extent to which dams in Nepal can be operated to efficiently Question 1. pass the large amounts of sediment eroded from Is there substantial potential for upstream high in the Himalaya remains unclear. reservoir storage in the Himalayan headwaters of the basin? While man-made storage potential in the Ganges is lower than generally believed, the natural Much has been written about the potential for large groundwater storage potential is far greater than water storage structures in the Nepal Himalaya. It generally believed. The Ganges is endowed with

6 Figure 2 this river system, even assuming an aggressive Current and Potential Surface Water Storage in development of system surface storage. the Ganges Basin On the other hand, the lack of substantial 600 – regulation will preserve a more natural hydrology 500 – in the river system, which provides a wide variety of ecosystem services that have not been quantified in 400 –

) this report. 3

300 – The Ganges SBA models indicate that even the

Volume (km Volume 200 – very large proposed Kosi High Dam could not fully control flood peaks in the Kosi River, which is a 100 – major flood-prone tributary of the Ganges. The Kosi High Dam would provide 9.5 billion cubic 0 – Average annual Baseline Active Total Protential meters of live storage. But it would be built on flow Storage Active Storage of All a river with an average annual flow of 55 billion Dams (baseline + 23 dams, including cubic meters (much higher in peak flood years) mega dams) and could therefore regulate only a small part of the floodwaters during the monsoon season. one of the world’s largest groundwater aquifers Moreover, the important question is not whether that could provide immense natural water storage the Kosi High Dam could reduce flood peaks; assuming energy were available to pump the but whether reducing flood peaks in the Kosi groundwater. While the use of groundwater storage River would stop flooding in Nepal and Bihar. is unlikely to provide significant flood control benefits Unfortunately, the evidence suggests that the dam’s at the basin scale, it could provide significant water impact on flooding would likely be modest, for two security for irrigation in some parts of the basin. main reasons.

Question 2. First, the flood-prone areas of southeastern Nepal Can upstream water storage in Nepal control and Bihar extend far beyond the Kosi Basin. flooding downstream? Figure 3 superimposes basin boundaries over the areas that were impacted by floods over the Large Himalayan dams in Nepal are commonly past decade. The image shows that most of the seen as the answer to the flooding that plagues flooding in Nepal and Bihar lies outside the Kosi the Ganges plains and delta, especially in areas of subbasin. Floods in the basin are often caused eastern Uttar Pradesh, Bihar, and Bangladesh. Model by intense localized rainfall, high flows in small results and research reveal a different picture. tributaries, embankment failures and obstructed drainage, rather than by peak flows overtopping The potential to control floods using upstream embankments in the major tributaries where large storage in Nepal is very limited. The active storage storage reservoirs could be built to diminish flood potential examined in this report (existing storage peaks. The development of the Kosi High Dam or plus additional major storage in the Nepal any other flood-control infrastructure upstream in Himalaya) amounts to approximately 25–30 the Kosi River will impact only a small part of the percent of average annual river flows. This is flood-affected areas downstream. simply too small a percentage to meaningfully regulate the full river system even if dams were Second, the level of the flood peak within the operated for the sole purpose of providing flood Kosi River is surprisingly unrelated to the extent control. This limited potential storage severely of flooding in southeastern Nepal and Bihar. constrains riparians’ ability to ever truly regulate Development of the Kosi High Dam could bring

7 THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

down the flood peak in the Kosi River – but the Lack of agricultural modernization—not lack of embankments on the Kosi River have never been water—is the crucial constraint to agricultural overtopped by flood waters. Flooding in the productivity in the specific areas of the Ganges Kosi (outside of its embankments) has resulted Basin that could receive these additional low flows. from embankment failures which suggest that, Even if the proposed dams were built (at high costs for purposes of flood control, embankment and likely over decades) agricultural modernization management should perhaps be prioritized over would be required to significantly increase reservoir development. productivity. This modernization would be beneficial regardless of upstream dam construction. While a moderate amount of flood flows could be stored in reservoirs on major Ganges tributaries, this Without better water management in irrigated adds little to flood relief because almost all of the areas, augmented low flows could have the major tributaries in the basin are fully embanked. paradoxical effect of reducing the productivity Lowering flood peaks within these embanked rivers of some land in Bihar and eastern Uttar Pradesh may provide some localized flood relief, but it would that have high groundwater levels even in the dry do so only at the tributary level and not effectively season. These areas tend to recover slowly during address the range of factors that contribute to the dry season as they drain and soil moisture flooding around the mainstem of the Ganges. evaporates. Augmenting low flows in such areas could disrupt this process of dry-season soil Question 3. recovery, and actually cause harm by increasing Can upstream water storage in Nepal waterlogging and reducing productivity. augment low flows downstream? In addition to potential agricultural gains, increased Himalayan reservoirs are expected to release water low flows could make important contributions in stored during the wet season for use in the dry the Ganges delta areas. These increased low flows season. It is widely believed that these releases could better buffer saline intrusion, sustain the could augment low flows for ecosystems, agriculture Sundarbans ecosystem, and maintain navigation and other uses across the lower Gangetic basin, services. These are important issues that require especially in the dry months preceding the monsoon. additional research to better understand their Modeling results confirm this expectation. socioeconomic and environmental implications.

Low-flow augmentation could indeed be significant Question 4. if all the large dams proposed for Nepal were built, Are there good alternatives or complements to approximately doubling river flows in the driest reservoir storage in the basin? months. Storing even a minor portion of the massive flood flows until the dry season could significantly Many believe that large-scale surface water storage increase low flows, especially in very dry years. Low- (dams) is the only option of adequate scale to meet flow augmentation may be large relative to current the basin’s water storage needs, given the region’s low flows, but it is negligible compared to peak growing populations and economies. This study finds flow, so the basic flow regime of the hydrological that enhanced, sustainable use of the basin’s vast system as it currently stands would not be changed groundwater aquifers could deliver additional water significantly by infrastructure development. on a scale comparable to the full suite of large dams in the Nepal Himalaya. However, the economic value of low-flow augmentation is unclear. Even though the Ganges Despite the severe overabstraction of groundwater basin is home to some of the largest irrigated areas seen elsewhere in South Asia, there are vast, in the world—and about 90 percent of the water untapped groundwater resources in the central and abstracted in the basin is used for irrigation—overall lower reaches of the Ganges Basin. These additional agricultural productivity is very low. groundwater resources, held in natural underground

8 Figure 3 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.

9 THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

aquifers, can be used sustainably assuming Seasonal use of the groundwater aquifer for water appropriate institutional arrangements. storage deserves careful consideration as a storage option in the basin, with or without additional As the Himalaya rose from the ocean, much of what investment in upstream reservoir storage. today is the Ganges Basin was formed by alluvial deposits from the rising and eroding mountains, Question 5. resulting in an extensive aquifer that is several Is there substantial untapped hydropower kilometers deep in some areas. It is a complex, potential in the Ganges Basin? multilayered system interspersed with clay layers and perched aquifers with possibly an extensive deep The Himalaya has long been seen as holding aquifer as well, though this has not yet been well enormous hydropower potential, adequate to meet explored (See Figure 4.) domestic energy needs in Nepal (where potential supplies far outstrip potential demand) and provide a Increased strategic and sustainable use of this significant surplus for trade in the region. This report groundwater, in conjunction with a well-managed confirms that potential. surface water system, could provide water supply benefits on a scale comparable to the full suite In Nepal more than 40,000 megawatts of of dams considered in this report; and it could economically feasible hydropower potential is possibly do so more immediately, at national, state believed to exist in the Himalayan headwaters of the Ganges. Less than two percent of that potential has or local levels, and at lower financial, social, and been developed. The suite of dams examined in the environmental costs. Ganges SBA would have an installed capacity of about 25,000 megawatts, generating an estimated A conjunctive use strategy (integrated management 65-70 terrawatt hours of power annually. The net of surface and groundwater) could be designed economic value of this potential hydropower is to help manage waterlogging and enhance the estimated at some US$5 billion annually, quite reliability of water supplies to tail-end users in significant relative to Nepal’s 2011 gross domestic surface irrigation schemes and/or downstream product (GDP) of $18.9 billion (current US $). irrigators in the eastern basin. It would require significant energy inputs as energy is needed to Hydropower development on this scale would, access (pump) groundwater. Achieving all of this, however, require considerable capital investment however, would also require significant reforms and take many years, and sediments would need to particularly in the policy and energy-pricing be effectively managed. Nonetheless, hydropower is environment, adequate institutional capacity, and an important source of clean energy in a region that real changes in farmers’ behavior. is enjoying high economic growth and hence rapidly growing power demands. The storage available in the shallow alluvial aquifers of eastern Uttar Pradesh and Bihar, which could be Question 6. utilized in the dry season and naturally recharged What is the magnitude of potential in the wet season, is 30–50 billion cubic meters. economic benefits from multipurpose water This is comparable to the low-flow augmentation infrastructure, and what are the tradeoffs (40–60 billion cubic meters) that could be achieved among different water uses? with the construction of 23 large dams in the Nepal Himalaya, because the water from upstream dams There is a general sense in the region that would suffer evaporative and leakage losses as multipurpose water infrastructure, such as storage- it traveled downstream, and the timing of water backed hydropower dams, will generate significant availability could not be targeted as precisely as the economic benefits. Yet there is no clear sense of the pumping of groundwater directly by a farmer onto relative values that will be generated by hydropower, his or her own fields. flood control, and low-flow augmentation, nor of the

10 Figure 4 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 tradeoffs among uses (and hence users.) This study Economic benefits for downstream agriculture and found that the overwhelming share of benefits (75-90 ecosystems are particularly difficult to determine but percent) derive from hydropower, and that tradeoffs they are likely to amount to less than 10-25% of the between uses are small. gross economic benefits of the dams. The evidence suggests that the current marginal (net) economic The Ganges SBA found that the gross economic value of increased surface water for irrigation is benefits of hydropower from the 23 large dams quite low in India and Nepal, around US$0.01 per examined under different scenarios of infrastructure cubic meter. If this is true, and no clear economic development would be in the range of US$3–8 value can be attached to ecosystems services, then billion per year (assuming that 25 percent of it could over 90% of total economic benefits will come from be sold as higher-value peaking power.) Without hydropower. If the value of additional irrigation taking into account project-specific environmental water were US$0.05 per cubic meter (a level of and social mitigation costs, the total net economic agricultural productivity that should be achievable, value of hydropower would likely be about US$5 but almost certainly overstates current returns) and billion per year. the value of ecosystem services were US$0.01 per

11 THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

cubic meter, the distribution of incremental economic believe that the majority of benefits from upstream benefits from development of all of the proposed water storage will not accrue from hydropower large dams in the Nepal Himalaya would be roughly development upstream, but rather from flood control 74 percent from hydropower, 18 percent from and irrigation benefits downstream. These findings irrigation, and 8 percent from ecosystem services suggest that the majority of immediate benefits will (see Figure 5). accrue to hydropower. A common understanding of the distribution of benefits is essential to negotiating In the future if agricultural productivity were enhanced equitable benefit-sharing arrangements. those benefits could rise dramatically. If the ecosystem benefits were better understood and quantified, they If upstream multipurpose dams were built today, could be much larger than we have assumed for with current low agricultural productivity and little illustrative purposes in these calculations. Even so, the flood benefit, the overwhelming share of economic absolute value of economic returns to hydropower benefits (75-90 percent) would be derived from would remain fairly stable because the tradeoffs hydropower. In the future, if agricultural productivity between upstream hydropower uses on the one hand, rises dramatically, the distribution of benefits and downstream agriculture and ecosystem uses on could change. the other, are smaller than previously assumed. Tradeoffs among different water uses are modest. For the most part, the economic tradeoffs among Infrastructure would be designed and operated hydropower, irrigation, flood control, and ecological much the same way whether the goal was to objectives are small. This is because there is little maximize hydropower, or to maximize flood and difference in the way upstream dams would be irrigation benefits downstream. The small amount operated to maximize hydropower generation on of storage relative to the flow of the Ganges the one hand, and downstream water supply on the or its tributaries should mean that reservoir- other. The objective for both is to store peak flows to filling policies are a manageable issue. And achieve steadier dry-season releases; the same water smaller storage areas mean less inundated land that generates hydropower would augment low flows and less resettlement of people. Negotiations in the dry season. The ability to control downstream over the design and operation of multipurpose flooding is limited regardless of the design and infrastructure with transboundary impacts should operation of dams, so there is little tradeoff therefore be tractable. anticipated between hydropower and flood control. The current economic value of downstream irrigation There is a tradeoff between using water for irrigation is surprisingly small compared with hydropower in the Ganges plains versus low-flow augmentation benefits, due to low agricultural productivity. At least to sustain ecosystem services in the delta, but in the near term, the direct economic benefits of there is currently insufficient evidence to determine upstream reservoirs would derive overwhelmingly whether this tradeoff is economically significant. The from hydropower. Power revenues will therefore evidence suggests that the marginal economic benefit lie at the heart of any benefit sharing negotiations. associated with surface water irrigation in the plains Delays in hydropower development result in lost is currently quite low and the economic value of power revenues that could easily be greater than the increased low flows for ecosystem services is uncertain. benefits of upstream development for downstream irrigation and flood control. Question 7. What are the cost- and benefit-sharing Flood benefits are minor and confined to dynamics of upstream water storage tributaries. Upstream storage will have negligible development in Nepal? basinwide flood impact. It could therefore be argued that benefit sharing with regard to flood It is generally perceived that downstream countries protection should be negotiated at the tributary will benefit greatly from upstream development. Some level (i.e., between two countries) rather than

12 Figure 5 Question 8. Distribution of Economic Benefits from All Is large infrastructure in Nepal the best Proposed Large Dams strategy for protecting downstream communities from floods?

Infrastructure is often seen as the most effective and reliable way to protect communities from endemic flooding in the Ganges plains. The findings of this report, however, show that a strategy exclusively focused on large upstream infrastructure cannot effectively protect communities lower in the basin.

There is no simple solution to the problem of flooding on the Ganges plains. In some areas of the world, a focus on large infrastructure (dams and embankments) has been fairly effective. However, in the highly variable Ganges system with its thousands Hydropower of silt-laden tributaries and limited storage, these Irrigation solutions will not be very effective. Low flow for ecosystems Droughts and floods take a significant toll on lives and livelihoods in the basin. Physical exposure basinwide. Conversely, benefit sharing with to water-related risks is closely linked with social regard to enhancing low flows for irrigation and vulnerabilities in the region. The least-advantaged ecosystems remains an appropriate issue for populations tend to live in areas with higher physical basinwide discussions. risks, while those with economic options tend to move away from the most physically insecure spaces. The principal unknowns in this equation are the To control flooding, many major tributaries are ecosystem and navigation values of enhanced low extensively embanked. However, these embankments flows in the delta, which could be significant. often fail, resulting in unanticipated and often catastrophic flooding. The study’s findings suggest that the benefit- sharing calculus is simpler than previously assumed To protect vulnerable communities in the Ganges because downstream flood control and agricultural Basin, a shift in focus is needed from “flood control” benefits are smaller than anticipated – at least in to “flood management,” a combination of structural the near to medium term. If this is the case, and and nonstructural interventions marked by a greater if there were mutual interest, India and Nepal emphasis on regional forecasting and warning should be able to negotiate fairly straightforward systems, embankment asset management, drainage, power development and trade agreements that also and, importantly, more localized “soft” responses recognize modest co-benefits in agriculture and including disaster preparedness, land use zoning, flood management. safe havens, flood insurance, and communications campaigns. While the SBA model results suggest that the benefit sharing calculus is simpler than previously thought, it Indeed, in recent years, this shift has been the remains the case that any decision on whether or not subject of a great deal of thoughtful advocacy. Flood to develop dams within Nepal is a decision that will protection for basin communities and the livelihoods and should be taken by Nepal alone, and will reflect of their people requires a broad, balanced a range of important factors beyond the costs and combination of “hard” and “soft,” as well as local benefits calculated here. and transboundary responses.

13 THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

Embankments remain the chief “hard” response Beyond embankment management, much can to floods in the Ganges basin. Their long-term be done through “soft” approaches to forecast impacts have been mixed, and mounting criticism flood events and prepare communities to deal is challenging the paradigm of using structural with them. Today’s revolutionary technological investments to control flooding. Some critics point advances in satellites, radar systems, and real- to the fact that embankment systems have altered time hydrometeorological systems, forecasting the hydrological characteristics of the basin because techniques, decision support systems, and last-mile high silt loads (typically spread on the plains areas communication hold much promise for the basin. during flooding) are now deposited within the embankments, raising river beds, reducing the Regional flood information systems and institutions capacity of the embanked channel to carry floods could be immediately beneficial. Building safely downstream, and increasing the risk of on national systems and capacities, regional embankment failure. cooperation in the development of basinwide water, weather and climate information management, Embankment failures can be catastrophic. forecasting capacity and disaster warning systems Embankment breaches or failures—like the could provide national institutions with significantly devastating Kosi embankment breach of enhanced regional forecasts for action. 2008—bring on sudden severe flooding that catches communities off-guard. The presence of In recent years, many soft options to prepare embankments can foster a false sense of security communities to deal with floods have been that manifests in a lack of preparedness, reduces proposed. Such nonstructural interventions are not social awareness of risk, and encourages behaviors new to the Ganges basin; indigenous settlement such as settlements in historic flood plains, thereby patterns and architecture in the Indian floodplains actually increasing vulnerability. show elevated housing built on bamboo posts and excavated ponds to provide water and act as flood Still, once built, embankments must be managed buffers. In addition, the people of the region have effectively: embankment monitoring and maintenance traditionally had strategies for moving themselves are an imperative for protecting communities in the and their animals out of harm’s way. They used Ganges basin. If modern embankment management boats during floods, and some communities systems are introduced, they can help assess needs for relocated to higher ground during the monsoon. maintenance, optimize resource allocation, and save lives and livelihoods. Many of these methods are still practiced by people living in flood-prone areas of the basin. In the Ganges basin, flood waters must be managed Other interventions could include large-scale flood both within the embankments and outside. plain management, disaster preparedness, land- Embankments disrupt drainage. River beds contained use planning, modification of cropping patterns, within embankments will rise as a result of the constant flood zoning, raised platforms and/or safe havens, supply of sediment from the High Himalayas. As a insurance, microfinance, and education and consequence, embankments must be constantly raised communications campaigns. to ensure they do not overtop. As embankments are raised they interrupt the normal flow of countless Effective protection of communities also requires small tributaries that can no longer make their way particular attention to gender. Studies in Bangladesh into the main river system and drain off the land. In have shown that women and children are 14 some reaches, drainage structures were designed into times more likely to die in the event of a natural embankments but many of these are now in disrepair disaster than men. Gender concerns also endure or buried under decades of silt deposits. A modern after natural disasters. In focus group discussions embankment management system must prevent floods undertaken for the Ganges SBA, women claimed extending outwards from the river channel, and also that in the aftermath of a disaster, when there was ensure drainage of the broad flood plain. limited food available to their families, they were

14 Figure 6 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.

generally the last to eat. Special attention must be The standard watershed management practice of paid to women’s needs and ideas in the design of reducing erosion by extending and maintaining forest appropriate flood management strategies. cover at the source of a watershed is not effective at high altitudes above the tree line. Although Nepal Question 9. has an impressive history of community forestry Is it possible to control sediment in the Ganges? management, with good results in local erosion management and livelihood benefits, these activities Many believe that in the Ganges, like elsewhere in are predominantly undertaken in the Siwaliks or the world, a combination of watershed management Churia Hills at elevations of just 600–1,200 meters to control erosion and upstream storage structures above sea level, far below the main sediment source might control sedimentation in the river. But the regions at 2,000–8,000 meters. Ganges is different. The extremely high volume of sediment also makes it The Ganges is one of the three most sediment-laden difficult and costly to manage using reservoir capture rivers in the world. Most of the sediment comes and storage. The volume of sediment is so large from erosion in the high Himalaya. The altitude that dams could not, and should not, be designed and terrain of the high Himalaya sediment source to capture and store it. The reservoirs behind these regions, as well as the nature of the soils and the large, expensive structures would quickly fill with ongoing tectonic processes, make it impossible sediment and, thereafter, produce very few benefits to undertake the scale of watershed management and potentially pose real safety risk. In fact, the dams interventions necessary to have any measurable built in the Himalayas would need to be operated impact on basin sediment loads. to try and reduce sediment build-up. If new dams

15 THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

are to be built in the Nepal Himalaya, managing With regard to the glaciers, the study found that sediment within the reservoir will be a central design while the rate of glacier melt is likely to increase challenge. Any infrastructure developed in the somewhat, glacier melt contributes only about 2 Ganges system would need sophisticated systems for percent of basinwide flow. In addition, melting flushing sediment downstream. occurs mostly during the high-flow season in the Ganges basin. In contrast to Europe and North Sediment, like floods, is a challenge that must America, or even in the western Himalaya, where be managed in the Ganges basin; it cannot be glacier melt contributes substantially to low summer fully controlled. Choices that are made today flows, the Himalayan glaciers in the Ganges basin potentially foreclose alternative options in the future. melt during the monsoon season when temperatures Continuing to raise embankments will result in are highest but rainfall is also heaviest. Thus, the deposit of sediments inside the embankments while changes in glacier melt will be an existential and lift the level of the river bed. Such a policy is challenge for some melt-dependent mountain increasingly hard to reverse. communities, it is not a major driver of basinwide hydrology in the Ganges. Question 10. What will climate change mean for the basin? The snow system, on the other hand, responds much more quickly to changes in temperature and Many fear that the Himalayan glaciers will melt precipitation. The expected temperature increase and change the Ganges River from a perennial in all seasons will result in less precipitation to a seasonally flowing river, and that changing accumulating as snow and in faster melting. The temperatures and precipitation patterns will create changes expected in the distribution, timing, and crippling water stress as well as more severe and intensity of precipitation would further complicate the more frequent droughts and floods. This study found process of snow accumulation and melt. The snow that climate change uncertainties in South Asia and acts as a natural “reservoir” in the Himalaya, storing the Ganges Basin in particular are extreme, but that monsoonal precipitation and augmenting low-flows; the range of mean basin runoff predictions is roughly the reduction of this function could impact seasonal comparable to the basin’s highly variable climate runoff, especially during critically low flows. today. Even the most extreme climate scenarios do not The study estimated temperature, rainfall and runoff change the basic findings of this report. In fact, for the Ganges Basin using 16 Inter-governmental greater climate extremes, variability, and uncertainty Panel on Climate Change (IPCC)-recognized Global only strengthen the logic of the Ganges SBA’s basic Circulation Models (GCMs). Although there appears recommendations. The effectiveness of large-scale to be a clear trend toward rising temperatures, infrastructure for flood control, and the reliability predictions regarding rainfall and runoff vary widely of existing large-scale diversions of surface water and point to the possibility of either increasing or for irrigation, could prove susceptible to climate decreasing water availability. The range of model change. But the recommendations of this study results underscores their uncertainty, and their are likely to become more pertinent under greater predictions can mask extremes, but these results climate extremes. do suggest that the scale and focus of today’s climate challenges – unpredictable and intense Enhanced forecasting and warning systems, in rainfall, alternating extremes of flood and drought concert with a suite of tailored, localized responses, – will continue to be the key climate challenges are urgently needed to cope with the variability in the coming decades. A focus on managing currently seen in the basin, and will be all the more current hydrological variability (whether or not it is vital as the climate changes. Similarly, the need attributable to climate change) is, therefore, a good for enhanced conjunctive use of surface water and place to start addressing the future climate change groundwater only becomes more compelling as challenges of the Ganges (see Figure 7). temperatures and hence evaporation rates, increase.

16 Figure 7 Predicted (a) and Historical (b) Flow Rates at Farakka on the Ganges

Predicted (a)

250

200

150 /s) 3

Flow (m 100

0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Historical (b)

300

250

200 /s) 3

150 Flow (m

100

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.

17 THE Ganges Strategic Basin Assessment: A Discussion of Regional Opportunities and Risks

In fact, concern about the additional uncertainty that to safeguard lives and assets, these systems could climate change could bring to the Ganges system also help provide the scientific data needed by could be a unifying factor in bringing basin riparians planners to sustain and develop the basin; by together for greater cooperation. farmers to enhance productivity and food security; and by climate researchers to understand, predict, The Way Forward and adapt to the changing – but also immediately challenging – climate in the Ganges Basin. There are daunting challenges in the Ganges River Basin, but there are also many opportunities for Immediate opportunities are also apparent at the cooperation and productive management of rivers bilateral and/or regional level for hydropower and water resources. development and trade. There is significant untapped potential in the basin and a steadily growing demand There is broad international consensus that all basins for clean energy. Moreover the benefit-sharing should be managed holistically and a range of river calculus of hydropower development appears simpler basin committees, commissions and organizations than commonly believed, for several reasons: (i) the around the world seek to institutionalize these good tradeoffs among different water uses (and hence practices. The Ganges would clearly benefit from the users) are modest; (ii) the current economic value of creation of an inclusive river commission that could downstream irrigation is surprisingly small compared develop a shared knowledge base and operational with hydropower benefits; and (iii) flood benefits are model of the basin, establish norms and protocols minor and largely confined to tributaries. This should for transparency and information sharing, and simplify negotiations. identify and pursue opportunities for cooperative development projects. Opportunities to enhance low-season water availability were also identified. Low flows can Recognizing that the basin states may choose not to be significantly augmented (potentially doubled establish a river basin organization in the near term, in the dry months) as a co-benefit of developing this study identifies opportunities to achieve some of multipurpose storage reservoirs upstream. But the the key functional benefits that could be provided by development of upstream storage reservoirs is a a river basin organization without the need for a full costly undertaking, and this report suggests that basin organization. storage investments would not be economically justifiable solely – or even significantly – on Flood management would be an excellent initial the grounds of their immediate contribution to focus for enhanced regional cooperation within enhancing agricultural productivity in the basin. the current institutional environment. Large dams Also, there are large areas of waterlogged land built to hold back floodwaters high in the Himalaya whose productivity could potentially be diminished have long been seen as the preferred strategy for if more water were applied during the dry season, managing the region’s devastating floods. But as which is a time that usually allows for recovery. an exclusive strategy, this is untenable. The physical storage volume available in the mountains is simply Upstream storage alone will not modernize too small to have a meaningful impact on basinwide agriculture in the basin. A range of interventions floods, although reservoirs may provide some is needed (and some are underway) to enhance amelioration within tributaries. agricultural productivity and support the livelihoods of poor farmers. These interventions are likely to The study’s findings argue for redoubling efforts in be beneficial regardless of the development of flood management, and in particular investments in upstream storage. regional information, forecast and warning systems and/or institutions, coupled with a range of hard and A promising and potentially more timely and cost soft, national and local level investments. In addition effective national-level alternative to upstream water to helping disaster risk management professionals storage reservoirs is the use of underground aquifers.

18 There is great potential to augment low-season A sediment strategy is needed. Ideally such flows by increasing groundwater utilization, within an a strategy would integrate sediment, flood appropriate energy-pricing and policy environment and landuse management; and explore tools and in conjunction with a well-managed surface ranging from modern embankment and drainage water system. In eastern Uttar Pradesh, enhanced management, to planned inundation areas, land groundwater use could produce additional storage zoning and insurance schemes. The choices made (and hence augment dry season water availability) on today around sediment and flood management will a scale comparable with the Himalayan dams, but be fundamental basin development choices that likely much more rapidly, and at lower cost. Enhanced ‘lock in’ options for generations to come. In the groundwater use would also be more scalable absence of a strategy, basin managers can only than water storage in the Himalaya. If upstream react in an ad hoc manner to imminent threats and multipurpose dams are found to be economically, periodic catastrophes. socially, and environmentally justified by the bundle of benefits they can produce (predominantly Finally, significant climate-change and other hydropower), additional dry-season water could prove uncertainties remain in the basin. Current data to be a co-benefit perhaps to complement more and models give little clear evidence of what the immediate interventions in conjunctive use. future holds. But perhaps this uncertainty itself could be a reason for enhanced cooperation. Enhanced low-season flows may also hold important It appears that mean hydrological variability potential to sustain ecosystem services, particularly in the future will be similar to the pronounced in the fragile Sundarbans (mangrove forests) of the variability seen in the basin today but extremes Ganges delta. The ecosystem values of increased may well be greater. Greater climate extremes, low flows downstream (e.g. in distributary rivers however, would only strengthen the justification such as the Gorai, which was once the mouth of for the main recommendations of this report. the Ganges) remain unsubstantiated, though they Investing in cooperative information management, might be high. Less expensive interventions such as forecast and modeling systems at the regional dredging through the sandbar that currently impedes level, along with a range of tailored interventions the flow of Ganges water into the Gorai in the at the national and local levels, would enhance nonflood season could improve low flows into that productivity and resilience in the Ganges Basin system even without upstream augmentation. today as well as the capacity to manage climate change in the future. A final important unknown is the economic value of augmented low flows in combating saline intrusion Several take away messages stand out as in the delta, and the importance of the Ganges opportunities for action based on the findings of the freshwater plume for the dynamics of currents and Ganges SBA: storm patterns in the Bay of Bengal. More study of the morphology and ecosystems values in the 1. Regional floods: focus on information & Ganges delta is urgently needed. institutions, not just infrastructure Sediment management is a perennial challenge in the basin. The extremely high volume of Upstream reservoir storage infrastructure cannot sediment that erodes off the high Himalaya control flooding in the basin. Real, immediate cannot be effectively controlled through watershed benefits can, however, come from cooperative management or captured in reservoirs. Sediments regional monitoring, forecast and warning will continue to be deposited across the basin and systems coupled with localized flood responses in particular within embanked reaches of the river, and modern embankment management schemes. causing river beds to rise and threaten surrounding areas with increasing risks of potentially catastrophic 2. Water storage to enhance low flows: look embankment failures. underground, not just upstream

19 Upstream reservoir storage can provide river beds rise. And so does the risk to people significant additional low season flows. and landscapes of catastrophic embankment Groundwater aquifers can also provide water failures. Sediment cannot be controlled at source storage on a scale comparable to the full suite in the High Himalaya. An integrated sediment- of major dams identified in the Nepal Himalaya, flood-landuse strategy is needed. possibly more immediately and at lower costs. The Ganges SBA has used the best available 3. Hydropower development: great potential knowledge and tools to examine the energy, with modest co-benefits fundamental strategic questions of the Ganges Basin. This new information is envisaged to Hydropower in the Nepal Himalaya can deliver encourage, rather than conclude, discussion abundant clean power for domestic use and on critical transboundary management issues regional trade, and improve persistent trade in the Ganges. It has challenged a number of imbalances. Modest co-benefits will be generated commonly held perceptions and concluded in irrigation and tributary-level flood control. that many are unrealistic. We hope this new knowledge will help the riparian states explore 4. Sediment strategy: innovate, before future new water development paths and move ahead options are buried cooperatively to sustainably manage this extraordinary basin and its ecosystems for the As sediments are trapped within embankments, benefit of its present and future generations.

Established in 2009, the South Asia Water Initiative (SAWI) aims to increase regional cooperation in the management of the major Himalayan river systems in South Asia to deliver sustainable, fair and inclusive development and climate resilience. It is designed to support countries improve and deepen transboundary dialogue, enhance the basin and water resources knowledge base, strengthen water institutions, and support investments that lead to reducing extreme poverty and promoting shared economic development. 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.