Process simulation of rainfall - runoff using the WMS model (A case study of the Qaresu basin- Iran)

Abstract

Assessment of runoff resulting from atmospheric precipitation has absorbed a particular importance in the study of hydrology, watershed management and water and soil conservation. The use of rainfall-runoff simulation model such as WMS has improved in recent years. This model has become a powerful tool for watershed hydrological process simulation combining GIS features and common hydrological models. In this study, in the software WMS, HEC-HMS model was chosen to predict flood of rainfall resulting from precipitation catchment area of Gharehsou. Therefore, first Digital Elevation Model was built in Arc GIS software environments and then entered WMS environment after some revisions. Thus, using TOPAZ model of river network, watersheds and sub-watersheds border as well as physiographic characteristics of sub-watershed were determined. To calibrate the model, observational showers in the studied basins along with three simultaneous flooding in the output of each sub-basin were selected. By optimizing the parameters of the curve number, initial loss and latency on the basis of two observational events, calibration model using observational hydrography were evaluated. The results showed a good fit to the peak discharge of observational hydrographic and simulated hydrographs and time difference to reach the peak was estimated equal to or less than 90 minutes. The results of the analysis sensitivity model to changes in initial soil moisture also showed that peak flow has a considerable sensitivity to changes in initial soil moisture.