Evaluating The hydrological response due to the changes in climate and land use on streamflow in the Karkheh basin, Iran

The Karkheh basin is one of Iran's largest and most waterlogged rivers. In this study, we aim to analyze the impact of Climate change and landuse change on the Karkheh basin using the Soil and Water Assessment Tool (SWAT). In this research, the considered land-use change is based on Iran's future policies, and climate change is studied by employing the RCP series and GCM in Mid-term (2040-2060) and Long-term (2080-2100). Firstly, changes in climate and land use are separately examined, and then the simultaneous impact of these two parameters is investigated. The results of the climate change study illustrate that the highest rate of change, which is a decrease of 14.3-22.8%, is achieved from the RCP 8.5 series in the long term. The results obtained from investigating the land-use change based on future policies in Iran show a maximum reduction of 7% in the average monthly runoff. The flow rate also decreases further when considering the simultaneous effects of both changes in the basin. In this case, the RCP 8.5 series shows a reduction of up to 39% in the long term. This study suggests that the effects of climate change are more significant than changes in landuse.