Advanced Flood Hazard Assessment using Frequency Storm, HEC-RAS 2D, and AIDR in the RAS Mapper Environment for the Tireh Dorud River in Iran

چکیده مقاله

Aims: Among natural disasters, flooding is recognized as a particularly destructive phenomenon that is increasingly occurring, posing a significant threat to urban infrastructure and surrounding land-uses. As a result, assessing flood characteristics, such as depth, velocity, and the extent of inundation, across different return periods is essential. This research aimed to develop and analyze the flood hazard map for Dorud City using the two-dimensional HEC-RAS model within the RASMapper environment. Materials & Methods: Initially, flood hydrographs for return periods of 2, 5, 10, 20, 50, 100, 200, and 500 years were predicted using the HEC-HMS hydrological model and the Frequency Storm methodology. These hydrographs were input into the two-dimensional HEC-RAS hydraulic model for flood hazard mapping and analysis. Geometric data(perimeters and break lines) and upstream/downstream boundary conditions were outlined in RAS Mapper using a 12.5-meter resolution Digital Elevation Model (DEM). Flood depth and velocity maps were subsequently generated for the specified return periods. Finally, flood hazard maps were created using the Australian Institute for Disaster Resilience(AIDR) method within RAS Mapper, utilizing the depth and velocity maps produced. Findings: The results show that the flood inundation areas for the 50-, 100-, 200-, and 500-year return periods are 9.587, 9.685, 9.708, and 9.761 km2, respectively.A significant portion of the flood-prone area is situated within the high to very high hazard zones. Conclusion: Furthermore, the AIDR analysis indicates that these areas are unsafe for all buildings, vehicles, and individuals, highlighting the urgent need to implement flood control measures to mitigate human and financial losses while promoting sustainable watershed management.