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- Title
Reviving the Ganges Water Machine: Potential and Challenges to Meet Increasing Water Demand in the Ganges River Basin.
- Authors
Amarasinghe, Upali A.; Muthuwatta, Lal; Smakhtin, Vladimir; Surinaidu, Lagudu; Natarajan, Rajmohan; Chinnasamy, Pennan; Kakumanu, Krishna Reddy; Prathapar, Sanmugam A.; Jain, Sharad K.; Ghosh, Narayan C.; Singh, Surjeet; Sharma, Anupma; Jain, Sanjay K.; Kumar, Sudhir; Goel, Manmohan K.
- Abstract
The Ganges River Basin (GRB) has abundant water resources, but the seasonal monsoon causes a mismatch in water supply and demand. This mismatch creates severe water-related challenges for the 600+ million people living in the basin, the rapidly growing economy and the environment. Addressing these challenges, which are only increasing, depends on how people manage the basin's groundwater resources. At present, more than 75% of the process depletion (evapotranspiration) from the irrigation, domestic and industrial sectors in the GRB is from groundwater withdrawals. The reliance on groundwater in the basin will increase further due to limited prospects for development of additional surface water storages. This report assesses the potential of the Ganges Water Machine (GWM), a concept proposed 40 years ago, to meet the increasing water demand through groundwater, and mitigate the impacts of floods and droughts. The GWM provides additional subsurface storage (SSS) through the accelerated use of groundwater prior to the onset of the monsoon season, and subsequent recharging of this SSS through monsoon surface runoff. There is a potential unmet water demand of 59-125 Bm3/year under two different scenarios of irrigation water use. However, the realizable potential is only 45-84 Bm3 due to supply constraints. The realizable potential is high only in seven subbasins in the northern and eastern parts of the GRB, is moderate to low in 11 sub-basins in the middle part, and there is little or no potential in four sub-basins in the western part. A preliminary ex-ante cost-benefit analysis, which captures the potential gains and losses after implementing a project, shows that the GWM is a financially viable intervention with a benefit to cost ratio of over 2.3. However, actual realization of its potential depends on many other hydrological and socioeconomic factors. The report shows that there is potential to enhance the subsurface storage by managed aquifer recharge during the monsoon season. It illustrates prospects of using solar energy for groundwater pumping, which is financially more viable than using diesel as practiced in many areas at present. The report further explores the limitations associated with water quality issues for pumping and recharge in the GRB, and discusses other related challenges, including availability of land for recharge structures and people's willingness to increase the cropping intensity beyond the present level.
- Subjects
BANGLADESH; GROUNDWATER &; the environment; WATER supply; WATER conservation
- Publication
IWMI Research Reports Series, 2016, Issue 167, p1
- ISSN
1026-0862
- Publication type
Article