Investigation of the SWAT Model Efficiency to Determine Water Balance Components(Case Study: Semirom Mehrgerd Watershed (

In this research, water balance components in Mehrgerd watershed was simulated using the SWAT hydrological model. The main purpose of this research is the model efficiency test and its ability to use as a water balance simulator in the Mehrgerd watershed. For this purpose, the necessary data such as precipitation, minimum and maximum temperature, relative humidity, sunshine hours, daily wind speed, monthly discharge and as well as required maps including digital elevation model (DEM), land use and soil were provided. and entered to the SWAT model. A sensitivity analysis was done using the )OAT( method to determine the sensitive parameters. The calibration and validation of the model were done by Sufi-2 algorithm. The calibration process was conducted for the period 2004 to 2012 while the validation process was from 2013 to 2016. Monthly runoff simulation accuracy was calculated using the determination coefficient (R²) and Nash Sutcliffe (NSE) index for calibration and validation 0.73, 0.69 and 0.71, 0.58, respectively. The results showed that 64 % of precipitation enters the atmosphere through evapotranspiration. Approximately, 31% of it goes to the waterway as the surface runoff and lateral flow. Finally, from 6 % of water entered into the soil layers, close to 1 % of it joins to the underground water. The results of this research show the acceptable performance of the SWAT model to simulate the water balance in Mehrgerd watershed. Therefore, this model can be used for water resources planning in this study area.