| Title: | Reviving the “Ganges Water Machine”: Where and how much? |
| Authors: | Muthuwatta, L., U.A. Amarasinghe, A. Sood and L. Surinaidu |
| Year: | 2017 |
| Journal: | Hydrology and Earth System Sciences |
| Volume (Issue): | 21(5) |
| Pages: | 2545-2557 |
| Article ID: | |
| DOI: | 10.5194/hess-21-2545-2017 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic only |
| Primary Application Category: | hydrologic assessment |
| Secondary Application Category: | groundwater and/or soil water impacts/processes |
| Watershed Description: | 944,000 km^2 Gerges River, which drains much of northern India. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Runoff generated in the monsoon months in the
upstream parts of the Ganges River basin (GRB) contributes
substantially to downstream floods, while water shortages
in the dry months affect agricultural production in the
basin. This paper examines the potential for subsurface storage
(SSS) in the Ganges basin to mitigate floods in the downstream
areas and increase the availability of water during
drier months. The Soil and Water Assessment Tool (SWAT)
is used to estimate “sub-basin” water availability. The water
availability estimated is then compared with the sub-basinwise
unmet water demand for agriculture. Hydrological analysis
reveals that some of the unmet water demand in the subbasin
can be met provided it is possible to capture the runoff
in sub-surface storage during the monsoon season (June to
September). Some of the groundwater recharge is returned
to the stream as baseflow and has the potential to increase
dry season river flows. To examine the impacts of groundwater
recharge on flood inundation and flows in the dry season
(October to May), two groundwater recharge scenarios are
tested in the Ramganga sub-basin. Increasing groundwater
recharge by 35 and 65% of the current level would increase
the baseflow during the dry season by 1.46 billionm3 (34.5%
of the baseline) and 3.01 billionm3 (71.3% of the baseline),
respectively. Analysis of pumping scenarios indicates that
80 000 to 112 000 ha of additional wheat area can be irrigated
in the Ramganga sub-basin by additional SSS without reducing
the current baseflow volumes. Augmenting SSS reduces
the peak flow and flood inundated areas in Ramganga (by up
to 13.0%for the 65%scenario compared to the baseline), indicating
the effectiveness of SSS in reducing areas inundated
under floods in the sub-basin. However, this may not be sufficient
to effectively control the flood in the downstream areas
of the GRB, such as in the state of Bihar (prone to floods),
which receives a total flow of 277 billionm3 from upstream
sub-basins. |
| Language: | English |
| Keywords: | |