Urban Flood Risk Mapping with Coupling Storm and Sanitary Analysis Software (ASSA) and HEC-RAS Model, Case Study of Ladan Urban Watercourse, Mashhad, Iran

This study aimed to perform flood risk mapping of the Ladan watercourse in ۹rd District of Mashhad city, Iran, through hydraulic and hydrological modeling. The analysis employed Storm and Sanitary Analysis (ASSA) and HEC-RAS ۶.۲ software. Rainfall–runoff modeling was based on a uniform rainfall pattern, while hydraulic simulations were conducted for return periods of ۲۵, ۵۰, and ۱۰۰ years. Flood hazard zoning for the ۱۰۰-year flood was prepared in accordance with Iranian Guideline for flood hazard mapping (Code ۸۲۱), in which the product of flow depth and velocity (V×D) was considered as the flood hazard index. The findings revealed that the Ladan watercourse can convey floods with return periods of ۲۵ and ۵۰ years. However, during the ۱۰۰-year flood, specifically, the initial ۲۰۰ meters of the channel were identified as critical zones where overtopping and road inundation are likely to occur.The results provide a practical basis for prioritizing vulnerable zones

کلیدواژه ها:

Risk Mapping ، Urban Flooding ، ASSA Software ، HEC-RAS ، rainfall-runoff