A recent study by researchers from the Indian Institute of Technology, Indore, has revealed that climate change is changing the composition of the water flowing from the Gangotri Glacier, which feeds the Ganges River. The findings, published in the Journal of the Indian Society of Remote Sensing, show a significant shift in how the river is being supplied with water.
Snowmelt Dominates but is Declining
The study, which analyzed 41 years of data from 1980 to 2020, found that approximately 64% of the discharge from the Gangotri Glacier comes from melting snow. An additional 21% comes from the melting of the glacier itself, while 11% is from rainfall runoff.
Despite snowmelt being the primary contributor, its overall share has been decreasing over time, particularly during the summer months. For example, the contribution from snowmelt in August dropped from 70% in the 1980s to just 41% between 2001 and 2010. Researchers attribute this decline to lower winter snowfall and higher temperatures in early summer.
A Shift in Peak Flow and the Need for Monitoring
The study also found that the peak discharge of the river has shifted from August to July since 1990. This change is directly linked to the increased early-summer melting. The highest decadal discharge was observed from 2001 to 2010, which coincided with the highest decadal temperature of 3.4 degrees Celsius during the study period.
The researchers stress the critical need for continuous monitoring and modeling of these changes. These efforts are essential for improving water resource management in glacier-fed river basins, which are vital for the millions of people who depend on them.