Performance-based analysis of earth dams: a case study of Hajji Qushan watershed, Iran

Recently, land-use change, as well as climate change through seasonal floods, have caused increasing damage to the Hajji Qushan watershed. Therefore, to reduce the peak discharge of floods, the construction of earth dams is necessary and inevitable. This study aimed to evaluate the effect of embankment structures on the reduction of peak discharge and their effects on the downstream flow regime. For this purpose, to present a favorite rainfall-runoff model and to route the mainstream channel, the HEC-HMS model was utilized. The required data included data from three rain gauge stations and two hydrometric stations. To delineate the boundaries of the watershed, ArcGIS 10.3 (HEC-GeoHMS extension) was implemented. To extract the digital elevation model (DEM), 10-m contour lines were used. The results showed the lack of satisfactory effects of dam construction on the reduction of peak flood discharge. The location of dam construction, reservoir capacity, and watershed area were of the factors that determined the possible reduction of flood risk.