Assessment of climate change impacts on streamflow through hydrological model using SWAT model: a case study of Afghanistan

Hydrological models always forecast variable status and, therefore, need further studies in models to make more real the management of the water resources. Analysis and execution of the watershed model are essential to carry out the valid assessment of water resources, individually in Kabul river sub-basin, where the modeling is a challengeable issue due to the lack of data. In this research, the Kabul river sub-basin watershed located at the Istalif station is modeled through the Soil and Water Assessment Tool (SWAT) to predict the future streamflow and climate change impacts on it. The model is calibrated with monthly discharge data for 2003-2010 and validated for 2010-2018. SWAT-CUP, which recently has developed with the capacity of providing the decision making for using manual and automated calibration and incorporating sensitivity and uncertainty analysis through (SUFI2) algorithm, is used for calibration and validation. According to coefficient of determination (R-2), Nash Sutcliffe efficiency, and present bias parameters, the calculation indicates an excellent performance for both calibration and validation periods and acceptable agreement between measured and simulated values of monthly scale discharge. Results show the importance of climate change effect on water resources, where it does not have only an effect on precipitation and temperature, but the streamflow is also directly influenced by climate change. The impact of climate change on the surface flow as well as land use/land cover change and other different scenarios is evaluated using calibrated SWAT model for further investigation.