Snow and glacier melt runoff simulation under variable altitudes and climate scenarios in Gilgit River Basin, Karakoram region

Abstract

The snow and glacial resource of the Himalayan region are a major source of fresh water for Indus basin irrigation system on which sustenance of millions of people depends. In the context of recent growth in global warming, it has become inevitable to estimate snow and glacier melt to manage future water resource in this region. In the present study, snow and glacier melt runoff was estimated from various altitudinal ranges and under variable climate scenarios in Gilgit River Basin of Pakistan using an integrated modeling approach. The findings of the study revealed > 80% runoff contribution from 4000 to 5000 m elevation range in the Gilgit Basin. The scenario of temperature increase by 1 °C indicated 9% and 13% rise in annual and summer flows, while 3 °C rise in temperature exhibited an increase of 75% and 95% in annual and summer flows of the Gilgit River. As a result of 10% rise in precipitation, the Gilgit River indicated an increase of 48% in annual and 57% in summer flows. A shift in snow melting period was predicted from April to March due to rising warm temperature. Major contribution in the runoff was estimated from snowmelt followed by glacier melt and rainfall. Overall rising trend in snow cover area was observed in the basin, which support the fact of mass gaining behavior of the Karakoram glaciers. The increased summer flows expected under future climate change in this basin should be managed to fulfill the growing water demands of numerous communities living in the downstream in the future.