The study of effective hydrological units on flood peak discharge in Hamedan-Bahar basin

In order to reduce the losses caused by floods and economize flood control projects in an area, construction of appropriate structures and operating watershed practices in areas with high risk of flooding is essential. One of the approaches to identify high risk flooding regions is watershed simulation and evaluation of sub-watersheds participation in outlet discharge. In this research, hydrological units of Hamedan-Bahar basins were simulated using ArcGIS and HEC-HMS hydrological model. Then, flooding indexes were calculated and their changes in all sub-basins were mapped.Effective hydrological units on peak discharge were identified and prioritized for watershed management, by reviewing and comparing these indexes. Site selection of flooding indexes showed that Bahador Beyg and Qareh Aghaj sub-basins had the highest and the lowest effect on flood peak, respectively. Analyzing results demonstrated that sub-basins with large areas or with huge amount of runoff not necessarily cause more effect on flood peak. Performance of management practices and construction of suitable hydraulic structures in studied hydrological units efficiently reduce flood damages in Hamedan-Bahar basin.