A projected increase in precipitation and glacier melt, due to climate change, will result in greater runoff from rivers in High Asia until at least 2050, reports a paper published online in Nature Climate Change this week. This suggests that discussion of water availability in this region must also include seasonal changes and extreme weather events.
Arthur Lutz and colleagues used a high-resolution model to quantify the hydrology of five major river basins - Indus, Ganges, Brahmaputra, Salween and Mekong - in the High Asia region. Different rivers have different runoff composition: for example, the upper Indus Basin is dominated by glacier melt, which makes up 40.6% of the streamflow, compared with the upper Mekong Basin, where glacier melt makes a minimal contribution. The team used climate model outputs to investigate how climate change will impact water availability up to 2050.
For the Ganges, Brahmaputra, Salween and Mekong river basins, glacier melt is not expected to change, as the effects of decreased glacier area will be compensated by increased melt rates. Rainfall is projected to increase due to climate change by up to 9.5% for these four basins. For the fifth, the upper Indus Basin, which is melt-dominated, the researchers expect accelerated melt, although rainfall is projected to slightly decrease.