Projected climate change in the Karkheh Basin, Iran, based on CORDEX models

Climate change is one of the most important challenges facing watersheds. In this study, the effects of climate change in the Karkheh River Basin (KRB), located in the Iranian plateau, have been investigated. The temperature and precipitation, as significant climatic parameters, have been investigated using the observed data (1980-2017), as a baseline period, and the projected data (2020-2090) which can be regarded as the output of the Coordinated Regional Climate Downscaling Experiment (CORDEX) model based on RCP8.5 and RCP4.5 scenarios. The status of the snow cover changes was evaluated using MODIS TERRA satellite sensors. The results show that there has been a downward trend in the precipitation amount in most of the KRB, at 95% confidence level. The projected results also show that the amount of annual precipitation will decrease with the deviation from the baseline period. According to RCP8.5 and RCP4.5 scenarios, the amount of annual precipitation will decrease by 88.2 and 56.1 mm, respectively, as compared with the baseline period. Moreover, the air temperature trend in the future period will be increased by deviation from the baseline period. Thus, by the end of this century and according to RCP8.5 and RCP4.5 scenarios, the minimum temperatures will rise by 4.5 and 2.5 degrees C, respectively. Evaluation of the snow cover status of the study area, based on the MODIS sensor over the last two decades, shows that the amount of snow covers has been decreasing, reflecting global warming in recent years. Therefore, long-term planning and water resources management, considering the climate change condition, are considered significant in this basin.