عنوان مقاله [English]
Estimation of runoff from atmospheric rainfall has particular importance in studies of hydrology project, watershed management and soil and water conservation. The use of models to simulation rainfall- runoff such as WMS has greatly expanded in recent years. This model by combines GIS facilities and common hydrological models has become a powerful tool to simulate the hydrological processes in watershed. In this study to predict floods from rainfall in the Gharasoo catchment by WMS software HEC-HMS model was chosen. For this purpose the digital elevation model in GIS software was made and after the necessary modifications exported to WMS model area. Then with the help of TOPAZ model, river network, watershed and sub basins boundaries and the sub basins physiographic characteristics were determined. To calibrate the model three measured rainfall in sub basins with three simultaneous outputs hydrograph were selected. Based on two observed hydrograph and optimizing the curve number, initial losses and lag time the model was calibrated and by using other hydrograph, was evaluated. The results show the good agreement of the observed hydrograph peak discharge and simulated hydrograph. Also result showed the time difference to reach the peak equal to or less than 90 minutes was estimated. Results of the analysis of model sensitivity to initial soil moisture changes also showed that peak discharge has a significant amount of sensitivity to initial soil moisture changes.