Climate change impact assessment on hydrology of Karkheh Basin, Iran

This paper addresses the impacts of climate change on hydrology and water resources in the Karkheh River Basin (KRB), which is the third most productive basin in Iran and has great potential for hydropower generation. The total potential capacity of reservoirs in this basin is more than 15 x 10(9) Mm(3), of which 40% has been built. The sensitivity of the KRB to potential climate change is investigated by simulating basin streamflow response under different climate change scenarios. A conceptual rainfall-runoff model (IHACRES) was first calibrated by using hydrological and streamflow observations. The model was then applied by downscaling two general circulation model outputs (CGCM3 and HadCM3) under three emissions scenarios (A1B, A2 and B1). The results show that, in the short term, annual mean temperature increases by about 0.9 degrees C, the annual amount of precipitation will not change significantly and annual streamflow decreases by 10-15%. In the mid and long term, respectively, temperature increases by more than 2.0 degrees C and 4.0 degrees C, precipitation decreases by about 15 and 17%, and annual streamflow decreases by about 25 and 32%.