Melting glaciers, more rain to swell Himalayan rivers

Indus, Ganges, Brahmaputra, Salween and Mekong rivers sustain agriculture and 1.3 billion people in a dozen countries

As the climate warms, increased melting of glaciers and more rain along the Himalayas is likely to enhance the flow of water into the big rivers that arise in this vast mountain range, according to research just published.

Researchers in The Netherlands and Nepal used high-resolution modelling to study how a warmer climate would affect run-off in the Himalayas into the Indus, Ganges, Brahmaputra, Salween and Mekong rivers in the coming decades. These five rivers sustain agriculture and 1.3 billion people in a dozen countries.

There would be increased run-off into the five rivers at least until 2050, Arthur F. Lutz and his colleagues noted in a paper carried in Nature Climate Change.

As a result of rising temperature, “a decrease in glacier extent is projected for all basins.” However, the decrease in glacier area would be compensated by a higher rate of melting. Consequently, the contribution from melting glaciers to the five rivers would not change much till 2050, they noted.

“If glaciers continue to retreat, at some point in time there will be a net decrease in melt water,” remarked Mr. Lutz in a press release issued by the Utrecht University in The Netherlands.

The Indus, however, was likely to see increased run-off from accelerated melting of glaciers in the period up to 2050, according to the paper.

In the case of the other four rivers, it would be more rain along the Himalayas that swell their flow. The upper Ganges basin could see its yearly run-off growing by up to 27 per cent. In the press release from Utrecht University, the scientists emphasised that their projections were only until 2050.