prioritization of sub-watersheds from flooding viewpoint using the Hec-Hms model in upstream of Shiraz Khoshk River

Flood is one of the complex and destructive natural phenomena that causes heavy damage every year. River routing and spatial situation of the sub-catchments are effective factors on flood in catchment outlet. Hence, for performing the flood control projects in upstream parts of catchments, their effects on flood should be investigated. In this research, the priority of the sub-watersheds was considered for flood occurance in the Chenar -Soukhteh watershed using the HEC-HMS model. After providing the data needed for flood hydrographs, the SCS hydrological simulation methods was used. Prioritization of the sub-catchments for flooding was done by utilizing the HEC-HMS model. Model calibration was done by sensitive parameters incuding initial losses, curve number and lag time. In order to evaluate the effects of flooding, two indicators of physical criteria including flux peak flow and flow volume were considered in each step. By applying the repetitive method for individual removal of sub-catchment, flood hydrographs corresponding to its precipitation were calculated for each sub-catchment. Then, with successive elimination of sub-catchment, the effect of each one in the production of flood output was obtained. The results showed that in events that were calibrated in medium CN conditions, sub-catchment 5 had the first priority in terms of flooding, while in the case of wet-calibrated CN, sub-catchment 6 has the first priority.