摘要：Residential and urban development in flood plains beds and riverbanks, regardless of hydrological and hydraulic conditions governing watershed and river, on the one hand, increase the risk of flooding and on the other hand, loss of investment in this area. In the present study to investigate the behavior of the rivers flood and how to expand its range in a reach of khoshke Rudan river, located in the Chaharmahal and Bakhtiari province, it was used from the integration of HEC-HMS hydrological and HEC-RAS hydraulic model. HEC-HMS model was calibrated for the study area by surveying of the cross sections of the rive using the rain gauge and rainfall gauging stations of the neighboring basins. Flood zones associated precipitations with periods of 10, 20, 50 and 100 years was determined by using HEC-GeoRAS extension in GIS environment. The results obtained from the study confirmed the high efficiency of the combination of GIS and HEC-RAS model and while provening the performance the model, recommend its application in program planning and management of residential and agricultural areas.
