A new study by researchers at the Indian Institute of Technology (IIT) Indore has found that nearly 64% of the water discharged from the Gangotri Glacier system which feeds the Ganga river comes from the melting of fallen snow. The study highlights how climate change is altering the hydrology of one of India’s most crucial glaciers in the Hindu Kush Himalaya region.
The analysis conducted with scientists from US universities and Nepal International Centre for Integrated Mountain Development (ICIMOD), shows that glacier melt contributes 21% while rainfall runoff accounts for 11% and baseflow another 4%.
Climate Change Shifting Glacier Patterns
Researchers observed a marked shift in the timing of peak discharge. Before 1990, the highest flow occurred in August but since then, it has moved to July a trend linked to reduced winter snowfall and increased melting during early summer.
The study, published in the Journal of the Indian Society of Remote Sensing also recorded the highest discharge about 29 cubic metres per second during 2001-2010, coinciding with the highest decadal temperature of 3.4°C across the study period (1980–2020).
“Over the last four decades, the composition of flow from the Gangotri Glacier System is changing due to climate change. This research offers the most detailed picture yet of how those changes have unfolded,” said Parul Vinze lead author and PhD scholar at IIT Indore’s glaci-hydro-climate lab.
The contribution of snowmelt to discharge in August has fluctuated sharply:
• 70% during 1980–1990
•54% during 1991–2000
• 41% during 2001–2010
•Rebounding to 57% in 2011–2020
Researchers explained that the decline until 2010 was caused by higher early-summer temperatures and reduced winter precipitation. The later recovery was linked to slight variations in snowfall and melt conditions.
Call for Continued Monitoring
The findings, based on 41 years of data, present a more detailed analysis compared to earlier studies, which often relied on shorter datasets or lower-resolution climate records. The authors stressed the importance of continued field monitoring and advanced modelling to better manage water resources in glacier-fed river basins, especially as climate change continues to reshape hydrological balances.
“Snowmelt remains the dominant contributor to the Gangotri Glacier annual discharge but rainfall runoff is steadily increasing a subtle yet critical shift in the basin’s water dynamics,” the study noted.