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Hydrological modeling has become an indispensable component of water resources research and management in large river basins
. Hydrological models help understand the past and current state of water resources in the basin, and provide a way to explore the implications of management decisions and imposed changes (such as climate change). In large river basins in the developing world, international donors have supported hydrological modeling for water resources management and planning, from two perspectives: to inform decisions relating to national development and poverty alleviation; and to prevent trans-boundary conflicts by promoting equitable allocation and access. Very significant effort and funding has gone into these models. In pursuit of improved accuracy, there is a tendency for each new group working in a basin to develop their own model, or suite of models, resulting in a plethora of hydrological tools for each major basin. The results are published, but model setup files, actual inputs and outputs are hardly ever shared in public domain. Due to limited access to observed data for model calibration, every “new” model is likely to be bound to use the same data and hence have similar deficiencies to previous modeling attempts. This paper explores the question: at what stage do we have enough information to stop modeling and get on with planning and management? How much modeling is enough? In this paper, we review the modeling effort in four major river basins in the developing world: Nile, Mekong, Ganges and Indus. For each basin, we provide an inventory of the main studies published since the year 2000; examine the types, purpose and use of existing models; overlaps and duplicate investments; constraints and gaps in knowledge. We then provide recommendations to assist research modeling groups and funding agencies to improve coordination, reduce repetition and improve the effectiveness of their investments in model development and application
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Water has been identified as a key resource for Nepal's economic growth
. Although the country has 225 billion cubic meters of water available annually, less than 7% has been utilized. Climate change is a frequent topic in national development discussions in part because of its possible impact on future water availability. This study assessed the likely impact of climate change on water resources development in the Koshi River basin, Nepal, using the Soil and Water Assessment Tool to generate projections for the 2030s and 2050s. Results suggested that the impacts are likely to be scale dependent. Little impact is projected at annual, full-basin scales; but at sub-basin scale, under both the IPCC's A2 and B1 scenarios, precipitation is projected to increase in the upper transmountain subwatersheds in the 2030s and in most of the basin in the 2050s and to decrease in the lower sub-basins in the 2030s. Water yield is projected to increase in most of the basin except for the A2 scenario for the 2030s. Flow volumes are projected to increase during the monsoon and postmonsoon but decrease during the winter and premonsoon seasons. The impacts of climate change are likely to be higher during certain seasons and in some sub-basins. Thus, if infrastructure is in place that makes it possible to store and transfer water as needed, the water deficit due to any changes in rainfall or flow patterns could be managed and would not be a constraint on water resources development. The risks associated with extreme events such as floods and droughts should, however, also be considered during planning
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This paper presents a comprehensive assessment of the water storage properties of glaciers and seasonal snow, carried out for the first time at a major river basin scale, for the Indus, Ganges, Brahmaputra, Amu Darya, Syr Darya and Mekong basins
. It analyzes the changes of glaciers and snow under recent climate change, i.e., between the baseline (1961-1990) and current (2001-2010) periods. The paper also addresses climate change sensitivity of glacier systems and the changes that might be expected under a warming scenario for the end of the twenty-first century
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The hydrological roles of glaciers and seasonal snow in the Indus, Ganges, Brahmaputra, Amu Darya, Syr Darya and Mekong basins are, for the first time, assessed comprehensively at a major river basin scale in this paper
. Contribution of glacier runoff, subdivided into renewable and nonrenewable components, and seasonal snowmelt to mean annual flow is evaluated for two time slices: 1961-1990 and 2001-2010. The recent changes of the hydrological roles of glaciers and snow, and the most likely changes of those under future climate change are analyzed
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The Nile provides freshwater not only for domestic and industrial use, but also for irrigated agriculture, hydropower dams and the vast fisheries resource of the lakes of Central Africa
. The Nile River Basin covers the whole Nile Basin and is based on the results of three major research projects supported by the Challenge Program on Water and Food (CPWF). It provides unique and up-to-date insights on agriculture, water resources, governance, poverty, productivity, upstream-downstream linkages, innovations, future plans and their implications. Specifically, the book elaborates the history and the major current and future challenges and opportunities of the Nile river basin. It analyzes the basin characteristics using statistical data and modern tools such as remote sensing and geographic information systems. Population distribution, poverty and vulnerability linked to production system and water access are assessed at the international basin scale, and the hydrology of the region is also analysed. This text provides in-depth scientific model adaptation results for hydrology, sediments, benefit sharing, and payment for environmental services based on detailed scientific and experimental work of the Blue Nile Basin. Production systems as they relate to crops, livestock, fisheries and wetlands are analyzed for the whole Blue and White Nile basin including their constraints. Policy, institutional and technological interventions that increase productivity of agriculture and use of water are also assessed. Water demand modeling, scenario analysis, and tradeoffs that inform future plans and opportunities are included to provide a unique, comprehensive coverage of the subject
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The Nile provides freshwater not only for domestic and industrial use, but also for irrigated agriculture, hydropower dams and the vast fisheries resource of the lakes of Central Africa
. The Nile River Basin covers the whole Nile Basin and is based on the results of three major research projects supported by the Challenge Program on Water and Food (CPWF). It provides unique and up-to-date insights on agriculture, water resources, governance, poverty, productivity, upstream-downstream linkages, innovations, future plans and their implications. Specifically, the book elaborates the history and the major current and future challenges and opportunities of the Nile river basin. It analyzes the basin characteristics using statistical data and modern tools such as remote sensing and geographic information systems. Population distribution, poverty and vulnerability linked to production system and water access are assessed at the international basin scale, and the hydrology of the region is also analysed. This text provides in-depth scientific model adaptation results for hydrology, sediments, benefit sharing, and payment for environmental services based on detailed scientific and experimental work of the Blue Nile Basin. Production systems as they relate to crops, livestock, fisheries and wetlands are analyzed for the whole Blue and White Nile basin including their constraints. Policy, institutional and technological interventions that increase productivity of agriculture and use of water are also assessed. Water demand modeling, scenario analysis, and tradeoffs that inform future plans and opportunities are included to provide a unique, comprehensive coverage of the subject
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This study assessed the variability of flows under present and 'naturalized' basin conditions in the Upper Ganges Basin (UGB)
. Furthermore, the PRECIS regional climate model (RCM) was used to generate climate projections for the UGB, with subsequent simulations of future river flows. Results show that the annual average precipitation, actual evapotranspiration (ET) and net water yields of the whole basin were 1,192 mm, 416 mm and 615 mm, respectively. Precipitation, ET and water yields were found to be higher in the forested and mountainous upper areas of the UGB. On an annual average, present-day flows throughout UGB are about 2-8% lower than under naturalized conditions. Dry and wet season flows under climate change (CC) scenario A2 are lower than that under present climate conditions at upstream locations, but higher at downstream locations of UGB. Flows under CC scenario B2 are systematically higher and lower than that under CC scenario A2 during dry and wet seasons, respectively
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Sharma, B.; Amarasinghe, U.; Xueliang, C.; De Condappa, D.; Shah, T.; Mukherji, A.; Bharati, L.; Ambili, G.; Qureshi, A.; Pant, D.; Xenarios, S.; Singh, R.; Smakhtin, V.
The basins of the Indus and Ganges rivers cover 2
.20 million km2 and are inhabited by more than a billion people. The region is under extreme pressures of population and poverty, unregulated utilization of the resources and low levels of productivity. The needs are: (1) development policies that are regionally differentiated to ensure resource sustainability and high productivity; (2) immediate development and implementation of policies for sound groundwater management and energy use; (3) improvement of the fragile food security and to broaden its base; and (4) policy changes to address land fragmentation and improved infrastructure. Meeting these needs will help to improve productivity, reduce rural poverty and improve overall human development
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The impacts of climate change on agriculture and food production in Southeast Asia will be largely mediated through water, but climate is only one driver of change
. Water resources in the region will be shaped by a complex mixture of social, economic and environmental factors. This report reviews the current status and trends in water management in the Greater Mekong Subregion; assesses likely impacts of climate change on water resources to 2050; examines water management strategies in the context of climate and other changes; and identifies priority actions for governments and communities to improve resilience of the water sector and safeguard food production
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This report attempts to introduce a prototype scoring system for the ecological status of rivers in India and illustrate it through the applications in several major river basins
. This system forms part of the desktop environmental flow assessment and is based on a number of indicators reflecting ecological condition and sensitivity of a river. The unique aspect of this study is that it interprets, for the first time, the existing ecological information for Indian rivers in the context of environmental flow assessment. The report targets government departments, research institutions and NGOs which are engaged in environmental flow management and associated policy development, and suggests some subsequent steps in environmental flow work in India
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