Comparing prioritization from flooding of sub-basins using HEC-HMS model and experimental methods in Eskandari Watershed

Identification of areas with high potential for flooding in the basin is one of the most important activities in flood control and reducing its damages. In this research, the possibility of prioritizing nine sub-basins from flooding point of view has been studied in Eskandari Watershed, using HEC-HMS. Also, the priorities of sub-basins were studied using flooding coefficient and peak discharge per unit area experimental methods. In order to run HEC-HMS model, plan rainfall with two, five, 10 and 50 years return periods were used. Flood hydrographs associated with each precipitation were calculated for each sub-basin, using the sequential removal method of sub-basins and removing CN in each sub-basin in each run of the model and their effect were computed in flood generation. Results showed that sub-basin I has the first priority is flooding potential, considering independent and depended sub-basins. Prioritization of sub-basins with two experimental methods had different results that are independent from a particular process. As E sub-basin had sixth priority in flooding coefficient method and third priority in the peak discharge estimating method. By comparing the prioritization of sub-basins in HEC-HMS model in different return periods, results showed that sub-basins prioritization in different return periods has specific process. Therefore, HEC-HMS model is more efficient compared to experimental methods in sub-basins prioritization in flooding.