The study focused on the Tang Allah Akbar Watershed in Shiraz, Iran, a region bordered by Baba Koohi Mountain to the southwest. The watershed, including a parking lot adjacent to a water accumulation pool, was analyzed to assess financial losses to vehicles during severe floods caused by unplanned urban development. The primary objective was to evaluate the stability of small cars in various flooded areas, calculate damage values for a typical compact car, and develop a flood risk map to enhance emergency management and vehicle flood insurance.

The PCSWMM model simulated hydrological and hydraulic conditions across the Tang Allah Akbar Watershed, divided into eight subcatchments. The model incorporated 601 stable 2D cells and 449 unstable cells within the parking lot. PCSWMM helped achieve project goals by simulating the flood hydrograph from a 4-hour rainfall event, calibrating peak discharge and time-to-peak values, performing 2D hydraulic analyses of flood depth and velocity, and providing a detailed understanding of parking lot dynamics during flooding.

The study revealed maximum flood depths up to 1.18 m and velocities as high as 3.27 m/s. A stability map based on the AR&R guideline identified stable and unstable areas for small vehicles, while damage values were determined using the HAZUS-MH depth-damage curve integrated with AR&R data. A flood risk map was created, highlighting damage-prone areas for vehicles. The project successfully extended the AR&R curve to assess vehicle instability, developed a new depth-damage model in stable regions using hydrodynamic indices, and produced a distributive flood risk map. These results provide critical tools and insights for urban planners, local authorities, and emergency managers to mitigate vehicle damage in urban floodwaters effectively.

Distribution map of flood maximum depth and maximum velocity in the parking lot

Risk map for small cars in the parking lot

Subcatchments and the model geometry for Tan Allah Akbar Watershed