Estimation of Water Balance in watersheds led to west-south frontiers and Persian Gulf by Semi Distributed SWAT Model

In the last decades, climate change and fluctuation of water balance have been the main reason to apply hydrologic models for estimating quality and quantity of water components as efficient tools in water planning of critical conditions. In addition, these hydrologic models with potential to study the effects of watershed management practices on the runoff components are suitable tools for optimization of watershed operations at present and future. In this research Soil and Water Assessment Tools (SWAT) model has been applied to estimate groundwater runoff for 6 provinces such as Eilam (Golgol Catchment), Boushehr (Baghan Catchment), Khozestan (Morghab Catchment), Fars (Shekastian Catchment), Kohkiloyeh & Boyer Ahmad(Tange Birim Catchment) and Hormozgan (Daragah Catchment) which are located in south and south west of Iran. In order to evaluate the performance of the model, hydrological data, soil, land use and Digital Elevation Model (DEM) entered for each catchment to run the SWAT model. SWAT-CUP with SUFI2 program was used for simulation, uncertainty and validation with 95ppu. P-factor and R-factor are two internal evaluation factors in SUFI2 program and indicators such as the coefficient of determination (R2) and Nash- Sutcliffe (NS) were used for evaluation of the model. The Nash-Sutcliffe coefficients in six mentioned catchments for calibration period are 0.66, 0.73, 0.40, 0.32, 0.53 and 0.78. They are 0.49, 0.48, 0.42, 0.45, 0.46 and 0.62 for validation period, respectively. Model calibration and validation results showed good performance in estimating the water balance of the basins studied. Except for Shecastian catchment, the evaluation results showed acceptable and favorable results for water balance in the study area.