Determining the Participation of Sub-Basins in Peak Discharge and Runoff Volume with HEC-GeoHMS Model

One of the most important measures in flood management projects is to investigate the participation of different sub-basins of a watershed in determining the various components of flood discharge from the basin. Due to the lack of hydrometric stations at the outlet of all sub-basins, achieving this goal requires simulation of the rainfall-runoff process in the sub-basins through hydrological models. In this study, HEC-GeoHMS model was used in Aydooghmush watershed in East Azerbaijan province of Iran. Three corresponding storm events and floods were used to calibrate and validate the model. The CN map of the basin was extracted in the GIS. Rainfall histogram with different return periods years was entered into the model and by successively removing different sub-basins, its impact on peak discharge and outflow volume Was determined from the desired basin. The results showed that the priority of participation in the peak discharge and flood volume of the basin outlet belongs to sub-basin one (W90), which is due to the larger area of this sub-basin. To achieve unaffected area characteristics, the highest peak discharge is related to sub-basin four (W120) and in case of flood volume, priority is given to sub-basin two (W100). The results provide the possibility of explaining the correct flood management policies through the management of critical sub-basins in the study area.