Simulation of streamflow using a hydrological model-distributed wetSpa in kasilian watershed

Rainfall runoff modeling and prediction of river discharge is one of the important components in flood control and management, hydraulic structure design and drought management. The goal of this study is to simulate the daily discharge in Kasilian watershed using WetSpa. The WetSpa model is a distributed hydrological and physically based model which can predict flood in watershed scale with various time intervals. The model uses topography, land use and soil type maps and also meteorological data for prediction of flood hydrographs. In this study the rainfall, evaporation and temperature data of Sangdeh meteorological station and discharge data of Valikben hydrometry station during the years 2003 to 2009 were used. 36 months from April 2003 and 30 months from March 2006 were selected for calibration and test of model, respectively. The results of WetSpa model showed that this model can simulate the river baseflow with Nash- Sutcliff criteria of 64 percent in validation period, but less accuracy with high discharges. The reason may be due to small and short travel time. The sensitivity analysis showed that groundwater flow recession and rainfall degree-day parameters have the highest and lowest effect on results. This model can simulate the water balance in Kasilian watershed as well.