Prioritization of Spatial Flooding Regions of Roodak Basin, in Tehran Province Using HEC-HMS Rainfall-Runoff Simulation Model

The available statistics in all world indicate increasing the frequency and occurrence intensity of flood events. So identifying the effective regions on outlet flood of watershed, on that area, is important and basic actions in flood control and decreasing damages arising from that. Present study was conducted prioritization of main subwatersheds in Roodak basin in Tehran province using HEC-HMS simulation model. After dividing watershed to numbers of subwatersheds, providing and completing needed information for model in Geographical Information System, selecting curve number method in loss section, SCS hydrological simulation method in transportation section and Muskingum method for flood routing, was determined roles of all subwatersheds in outlet flood hydrograph by Succession Single Subwatersheds Elimination method and according to it, prioritization was done. This research studied relationship between flood and subwatersheds area too. The results of research show that, Kelookan subwatershed, has more effect than on outlet flood from basin. The results also show that, subwatersheds participation in outlet flood doesn t have direct relationship with their area.