Flood inundation and hazard mapping using the HEC-RAS 2D model: a case study of Adoori River, Iran

Accurate flood hazard mapping is considered essential for effective water resource management. The objective of this study is to perform a comprehensive numerical analysis of Adoori River flooding in Bam city in Iran, with a special emphasis on precise inundation maps of hazard areas. This is accomplished using the hydraulic modeling software, HEC-RAS 2D. Digital Elevation Models are used in the methodological approach to understand the geometric characteristics of river. In order to facilitate hydrological rainfall-runoff modeling, basin physiographic properties are integrated using HEC-HMS. The model calibration incorporates empirical data from the 2016 flood event, resulting in acceptable statistical indices consist of Nash-Sutcliffe index = 0.7 and the coefficient of determination R2 = 0.8. Hydraulic modeling is used to achieve high accuracy in hazard inundation mapping using 25-year and 100-year floods as boundary conditions. The area of inundation zones for the 25-year and 100-year floods are about 60 km2 and 68 km2 respectively. The floods with a 100-year return period tend to encroach on flood-prone areas approximately two hours earlier than floods with a 25-year return period. The results can be valuable to hydrology specialists, serving as a foundation for forming informed flood control policies and enhancing flood management efforts.