Despite melting of Himalayan glaciers due to global warming, water levels of critical Himalayan rivers like Ganges and Indus will not drop over the next century due to an increase in monsoon rains, say scientists.
The latest research led by Dr Walter Immerzeel, a scientist from Utrecht University in Netherlands and visiting scientist at the International Centre for Integrated Mountain Development (ICIMOD) in Nepal, indicates that increasing rains would prevent rivers from drying up.
The research report which was made available today said climate change will result in smaller glaciers and less melt-water in the Himalayas.
Himalayan rivers like Ganges and Indus whose water depends on the melting of glaciers and snow are essential to the food supply of hundreds of millions of people in the lower-lying areas in India, Bangladesh, and Pakistan.
According to the study, glacial melting will hit the peak somewhere around 2070 and the glacial discharge will start to drop. However, at that time too the increase in precipitation will compensate for this, as a result of which the annual discharge from the river basin will increase again.
To understand the impact of climate change on river discharge in the Himalayas, the researchers created computer models of the glacier movements and water balance in two watersheds that vary greatly with regard to the climate and size of the glaciers.
In the eastern watershed (Langtang in Nepal, where the Ganges has its source), the relatively smaller glaciers melt quite quickly, and the increased water discharge is a result of the increase in monsoon rains.
The western watershed (Baltoro in Pakistan, where the Indus has its source), on the other hand, is dryer and colder and has much larger glaciers. The increase in discharge in the basin there is due to increased glacial melting.
Director General of ICIMOD, Dr David Molden, said this important research challenges perception of the impact on climate change on water resources.
"However much work remains, including better understanding of changes in monsoon patterns and snow-melt, and resulting variability in river flows, including low flows and flood peaks," he said in a statement.