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- Title
The Impacts of Water Infrastructure and Climate Change on the Hydrology of the Upper Ganges River Basin.
- Authors
Bharati, Luna; Lacombe, Guillaume; Gurung, Pabitra; Jayakody, Priyantha; Chu Thai Hoanh; Smakhtin, Vladimir
- Abstract
Provision of detailed continuous long-term hydrological time series data for any river basin is critical for estimation, planning and management of its current and future water resources. Most of the river basins in India are data poor, including its iconic river - Ganga (Ganges). This study assessed the variability of flows under present and 'naturalized' basin conditions in the Upper Ganges Basin (UGB) (area of over 87,000 square kilometers (km²)). The naturalized basin conditions are those that existed prior to the development of multiple water regulation structures, and hence may be seen as a reference condition, a starting point, against which to evaluate the impacts of planned basin development, as well as the impacts of future climate change (CC) on basin water resources. The later impacts are also part of the study: 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 millimeters (mm), 416 mm and 615 mm, respectively. However, there were large variations in both temporal and spatial distribution of these components. 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 the UGB are about 2-8% lower than in naturalized conditions. The percentage of flow reduction is the highest during the dry months as water is being withdrawn for irrigation. Dry and wet season flows under CC scenario A2 (scenario corresponding to high population growth with slower per capita economic growth and technological change) are lower than those in present climate conditions at upstream locations, but higher at downstream locations of the UGB. Flows under CC scenario B2 (corresponding to moderate population growth and economic development with less rapid and more diverse technological change) are systematically higher and lower than those under CC scenario A2 during dry and wet seasons, respectively. The dates of minimum daily discharges are highly variable among stations and between different CC scenarios, while the dates of maximum flow are delayed downstream as a result of the delay in the onset of the monsoon in the lower parts of the basin. The report also provides actual simulated discharge time series data for all simulated scenarios, in the overall attempt to augment the river flow data for this important river basin and to facilitate the use of these data by any interested party.
- Subjects
GANGES River (India &; Bangladesh); INDIA; WATERSHEDS; STREAMFLOW; WATERSHED hydrology; CLIMATE change
- Publication
IWMI Research Reports Series, 2011, Issue 142, p1
- ISSN
1026-0862
- Publication type
Article