Evaluation of the hydrological response of the Kiwi Chai catchment area to future climate changes with the SWAT model

Climate change has a direct impact on hydrological components and water resources and plays an important role in aggravating possible risks such as drought and floods. Therefore, it is necessary to investigate the effects of climate change on water components such as runoff. This study evaluates the effect of climate change on climatic parameters (temperature and precipitation) and the amount of runoff in Kiwi Chai basin from an environmental point of view. The hydrological model of the Soil and Water Assessment Tool (SWAT) was used to analyze the effects of climate change on the water resources of the Kiwi Chai basin, which is one of the Sefidroud sub-basins. Runoff simulation by applying climate change conditions for models (EC-EARTH, HadGEM2-ES, MIROC5, MPI-ESM) under two scenarios (RCP 4.5 and RCP 8.5) in three periods (2040-2021), (2041-2060), ( 2061-2080) and statistical analysis was performed to identify which climate model is more consistent with the changes in the mean and standard deviation of the historical series. An increasing trend in precipitation and a significant increase in average annual temperature were predicted in the early, middle, and late 21st century. The results of simulation of basin runoff with SWAT model also showed a significant decrease in basin runoff in future periods compared to the base period. These findings provide local water management authorities with useful information to aid decision-making in the face of climate change.