Quantifying the changes in the runoff and its components across the Upper Indus River Basin under climate change

Abstract

The runoff from the Upper Indus River Basin (UIB) is considered vital for sustainable water supply and agriculture. Climate change may alter the runoff and affect the availability of water. This study employs a hydrologic model and the climate projections of fine-resolution Meteorological Research Institute-Atmospheric General Circulation Model (MRI-AGCM) (0.1875°) to assess the impacts of climate change in the future (2075–2099) on the flows in the UIB and its sub-basins. The simulations have shown satisfactory results compared to the observed ones. Furthermore, simulated snow-cover was compared with estimated snow-cover by Moderate Resolution Imaging Spectroradiometer (MODIS). According to the results, meltwater from glaciers contributes to about two-thirds of the annual runoff from the UIB. According to the projections, the future temperature will increase by 5.3 °C and annual precipitation will increase by 17% across the UIB. Despite this increase, the annual river flows were projected to decrease by 14% in the future because of depleted glacier melt. Furthermore, the detailed hydrologic responses in selected sub-basins showed different patterns in the future depending on the climate and elevation. In an eastern sub-basin, flows will increase by 58% because of enhanced glacier melt and higher precipitation. Contrarily, two western sub-basins will experience the reduction of the flow by 30–70% because of the glacier retreat.