The study found groundwater, not glacial melt, is the principal source sustaining the river during the summer months

The Ganga River silently loses over 50 per cent of its water as it flows through the plains, a recent study by the Indian Institute of Technology (IIT) Roorkee has revealed.

Under Abhayanand S Maurya, the research published in the journal ‘Hydrological Processes’ examined two decades of data on the Ganga’s summer flow. The findings challenge popular assumptions about its hydrology and call for urgent policy attention.

The study found groundwater, not glacial melt, is the principal source sustaining the river during the summer months. As the Ganga descends from the Himalayas to the central plains, its volume increases by nearly 120 per cent due to steady contributions from shallow aquifers and hand pumps. Contrary to satellite-based claims of large-scale depletion, the research finds the groundwater system in the central Ganga plain to be largely stable.

Over 58 per cent of this water is lost through evaporation during the scorching summer, significantly reducing the river’s flow before it reaches the lower basin.

The findings underscore the importance of restoring tributaries and investing in groundwater recharge to maintain year-round flow. With climate change and human pressures increasing, Maurya said protecting underground water reserves is critical to sustaining the Ganga’s ecological and cultural legacy.