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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
25 Sep 2015
Review status
A revision of this discussion paper was accepted for the journal Hydrology and Earth System Sciences (HESS) and is expected to appear here in due course.
Reviving the "Ganges Water Machine": where and how much?
L. Muthuwatta1, U. A. Amarasinghe1, A. Sood1, and S. Lagudu2 1International Water Management Institute (IWMI), Colombo, Sri Lanka
2Council for Scientific and Industrial Research - National Geophysical Research Institute (CSIR-NGRI), Hyderabad, India
Abstract. Surface runoff generated in the monsoon months in the upstream parts of the Ganges River Basin contributes substantially to downstream floods, while water shortages in the dry months affect agricultural production in the basin. This paper examines the parts (sub-basins) of the Ganges that have the potential for augmenting subsurface storage (SSS), increase the availability of water for agriculture and other uses, and mitigate the floods in the downstream areas. The Soil and Water Assessment Tool (SWAT) is used to estimate sub-basin-wise water availability. The water availability estimated is then compared with the sub-basin-wise un-met water demand for agriculture. Hydrological analyses revealed that five sub-basins produced more than 10 billion cubic meters (B m3) of annual surface runoff consistently during the simulation period. In these sub-basins, less than 50 % of the annual surface runoff is sufficient to irrigate all irrigable land in both the \textit{Rabi} (November to March) and summer (April to May) seasons. Further, for most of the sub-basins, there is sufficient water to meet the un-met water demand, provided that it is possible to capture the surface runoff during the wet season. It is estimated that the average flow to Bihar State from the upstream of the Ganges, a downstream basin location, is 277 ± 121 B m3, which is more than double the rainfall in the state alone. Strong relationships between outflows from the upstream sub-basins and the inflows to Bihar State suggested that flood inundation in the state could be reduced by capturing a portion of the upstream flows during the peak runoff periods.

Citation: Muthuwatta, L., Amarasinghe, U. A., Sood, A., and Lagudu, S.: Reviving the "Ganges Water Machine": where and how much?, Hydrol. Earth Syst. Sci. Discuss., 12, 9741-9763, doi:10.5194/hessd-12-9741-2015, 2015.
L. Muthuwatta et al.
L. Muthuwatta et al.
L. Muthuwatta et al.


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Short summary
Agricultural production in the Ganges River Basin is affected by the water shortage in the dry months while the excess water during the rainy season causes floods in the downstream. Annual total surface runoff generated in the Ganges River Basin is about 298 ± 99 Bm3, and runoff in the monsoon months contribute upto 80% of this total runoff. Comparison of sub-basin-wise surface runoff with the estimated un-met water demand indicated that capturing only a portion of the wet-season runoff would be s
Agricultural production in the Ganges River Basin is affected by the water shortage in the dry...