SWAT and IHACRES models for the simulation of rainfall-runoff of Dez watershed

Due to the scarcity of meteorological observation stations in some areas, there is not enough data available for hydrological simulation as one of the main subjects of hydrology and environmental subjects. This can be partially solved by extracting the required data from global climate centers. The essential data for modeling rainfall-runoff of Dez watershed (16,000 km2), Khuzestan province, Iran, for a 20-year period (1990–2010) were obtained from NCEP CFSR climate center. The simulation (calibration and validation) was done by Soil and Water Assessment Tool (SWAT) and Identification of Unit Hydrographs and Component Flows from Rainfall, Evapotranspiration and Streamflow (IHACRES) models. The SWAT-CUP software has been used for optimization, calibrating and analyzing the uncertainty of the SWAT model by communicating with the model. The ability of the models to simulate the runoff of the basin was determined using the coefficient of determination (R2) and Nash–Sutcliffe efficiency (NSE). R2 and NSE for the SWAT model were 0.75, and 0.78 (calibration), and 0.59 and 0.72 (validation); for the IHACRES model, they were equal to 0.63 and 0.69 (calibration), and 0.54 and 0.66 (validation), respectively. The SWAT model performed better than the IHACRES model by efficiently using the climatic database of NCEP CFSR center. The IHACRES model was also able to simulate the runoff of the watershed with a relatively high correlation with the observational data. It is possible to simulate and predict rainfall-runoff of the Dez watershed using the tested models for taking the measures, which may avoid natural phenomenon including flooding.