Investigating the Effects of Land Use Changes on the Runoff of Qara Chai River Basin Using the SWAT Model

The present study analyzed changes in land use and its effects on the runoff of Qara Chai Watershed in Hamadan Province using the SWAT model. To this aim, Landsat OLI-TM satellite images of the years of 2001-2020 were used. First, the relevant images were obtained and the necessary pre-processing steps, including atmospheric corrections, were applied by using the FLAASH method. To increase the classification accuracy, the multispectral images were combined with the panchromatic images and the spatial resolution was enhanced up to 15 m. Then, the classification process was done by using the object-oriented method and the nearest neighbor algorithm. The SWAT model was utilized for hydrological simulation of the basin and SUFI-2 algorithm was applied in SWAT-CUP software for conducting sensitivity analysis, calibration, and validation. Due to the sensitivity of the model to the initial loss parameter, it was recalibrated based on the initial loss values. The values ​​of the coefficients for the calibration period were between 0.72 and 0.90 and the model validation results confirmed the calibration accuracy. Assessment of the efficiency of the model by using Nash Sutcliffe coefficients, p-factor, R, and r-factor indicated its high capability for simulating the related runoff.