River Indus vs. River Ganga Basin Trends
Context:
A new study by IIT-Gandhinagar published in Earth’s Future (American Geophysical Union) reveals that the Indus and Ganga river systems are moving in opposite hydrological directions, with significant implications for South Asian water security.
Key Findings (1980–2021):
Indus Basin:
Overall annual streamflow increased by 8%
This is primarily driven by rising precipitation.
However, its eastern tributaries (Ravi, Beas, Sutlej) showed significant declines.
Ganga Basin:
Overall streamflow declined by 17%.
The study attributes 60% to 80% of the decline in Ganga sub-basins to intensive groundwater extraction.
Normally, groundwater feeds rivers (base flow) during dry months.
In parts of the Yamuna and Upper Ganga, this flow has reversed:
Rivers are now losing water to depleted aquifers.
In the Ganga basin, groundwater contributes 50–70% of annual river flow, making its depletion critical.
Implications for Treaties:
Indus Waters Treaty (1960):
The study suggests a need to re-look at the treaty.
Agriculture in Pakistan (Western rivers) is less affected due to increased precipitation, whereas Indian Punjab (Eastern rivers) faces severe groundwater decline.
Without coordinated groundwater regulation, the drying of the Ganga basin is likely to intensify, threatening food security in the region.