Impact Assessment of Urban Waterlogging on Urban Road Safety Risk Based on MIKE FLOOD Coupling Model

The assessment of urban flood risk plays a crucial role in preventing flood disasters, yet there is limited research on road safety risk assessment. Taking Xiushan County, Chongqing Municipality, as the study area, road safety risk was assessed using the MIKE FLOOD coupled model. The results indicate that surface water depths are mainly concentrated between 0.05 to 0.15 meters, and the spatial distribution of water depths under different return periods（P=1%～20%） is generally consistent. The duration of water accumulation is mainly between 60 to 90 minutes, and the water accumulation flow velocity is mainly greater than 0.8 meters per second. In some areas of the old city, the infrastructure safety risk is primarily at a very high level（water depth ＞0.4 meters）, while in other areas, it is predominantly at a slight risk level（water depth ＜0.5 meters）. Pedestrian safety risk of the old city is primarily at level III（hazard index 1.25～2） in some areas, while in other areas, it is primarily at level I（hazard index ＜0.75）. The traffic operation conditions on most road sections are mainly at the unimpeded level（retention coefficient ＞0.7）, but some road sections are interrupted during heavy rainfall（retention coefficient = 0）. The research findings can provide scientific basis for traffic control and passage warning before urban flooding occurs.