حوضه آبخیر

Floods cause significant destruction to the economic and social structures of societies each year, resulting in substantial financial and human losses. One of the contributing factors to flooding is urban development around rivers. Due to climate change, Iran has become increasingly susceptible to floods in recent decades, particularly because of its hot, dry, and semi-arid climate. The aim of this research is to conduct flood zoning of the Godar watershed using the HEC-RAS hydraulic model. To achieve this, we first determined the area’s runoff characteristics using satellite images from 2018, a land use map, and the SCS runoff curve number model. Next, we simulated the flood discharge for the basin with return periods of 25, 50, 100, and 200 years using the HEC-HMS hydrological model. Subsequently, we prepared the flood zoning map for the Godar watershed area, encompassing the cities of Naghadeh and Oshnavieh, based on the desired return periods with the help of the HEC-RAS hydraulic model. The results indicate that as the return periods increase, the area of the flood zone in the Godar watershed expands, with increases of 1,255 hectares for the 25-year return period, 1,316 hectares for the 50-year return period, 1,370 hectares for the 100-year return period, and 1,419.7 hectares for the 200-year return period. The results of this study showed that the longer the return period, the larger the area affected by the flood. Studies also show that the HEC-HMS model is suitable for estimating discharge in basins that lack hydrometric stations. The results of this study may be useful in flood management and help reduce the vulnerability of this river to floods.