Projected energy and hydrological budgets over the Indus River Basin under a CORDEX-SA regional climate model framework

Abstract

The Indus River is one of the largest transboundary rivers in Asia originating from Tibet autonomous region of China. This supplies water to the great plains of Punjab, significantly influencing agricultural productivity and shaping the socioeconomic conditions of the region's inhabitants. The present study investigates the potential impact of climate change on the water resources of the Indus River Basin (IRB). The study utilized the output from a regional climate model, REMO, to examine the projected change in energy and hydrological budget at 1.5, 2 specific warming levels and at the end of the century over IRB under three different representative concentration pathways (RCPs). The projected rise in the temperature from the historical period to the end of the century (both summer and winter) can be attributed to the increase in net downward energy flux compared to net upward energy flux. In the mid-century, the downward longwave radiation flux (sensible and latent heat flux) plays a dominant role in determining the surface energy balance during winter (summer). While, the combined impact of the energy components becomes more dominant at the end of the century for both seasons. Rainfall is projected to increase in the mountains of the upper Indus basin and gradually decline on the plains of the lower Indus basin till the end of the century. The projected decline in water storage over the plains of IRB can be attributed to the combination of declining rainfall and increasing evaporation. This will exert significant pressure on agriculture, industry and more importantly on the potable water supply. The IRB is found to be highly susceptible to climate extremes such as floods and drought. Climate change information is crucial for policy planners, governance, decision-makers, management authorities, etc. as it enables the implementation of better management practices, Additionally, it provides both short-term and long-term goals for a mitigation-based approach to reduce the impact of climate change