Impact of climate change on snow precipitation and streamflow in the Upper Indus Basin ending twenty-first century

The study investigates the impact of changes in the form of precipitation and the consequent changes in the snowmelt contribution under changing climate on the streamflow in the Lidder, the most glaciated watershed in the Jhelum basin situated in the Upper Indus Basin (UIB). The Tracer Aided Catchment-Distributed (TAC) model is used to assess the present and future status of snowfall, snowmelt contribution and streamflow changes using the observed and projected climate data from an ensemble of 8 global climate models under various Representation Concentration Pathways (RCPs), viz. RCP2.6, RCP4.5, RCP6.0 and RCP8.5. Snow precipitation presently comprises 52% of the total annual precipitation and contributes ~ 55% to the annual streamflow with the peak observed in May in the Lidder River. However, projections to the end of twenty-first century under various RCPs indicate that there shall be considerable decrease in both the snow precipitation and snowmelt contribution to the streamflow. Moreover, early snowmelt is predicted during spring by the end of the twenty-first century under climate change, which leads to the shifting of streamflow peak from the late spring to early spring in the upstream and from summer to spring in the downstream areas of the basin. The observed streamflow shows a noticeable shift in the streamflow peak after 1990s and is more prominent in the downstream areas of the basin. The projected future climate change, snowfall depletion and streamflow changes are expected to significantly impact the timely availability of waters for various uses, flood vulnerability and sharing of the Indus waters.