Impact analysis of urban super-standard flood disasters based on MIKE+

In recent years, urban areas have increasingly experienced record-breaking extreme rainfall events, making flooding a critical challenge to sustainable urban development. This study utilizes the MIKE + integrated water simulation software to analyze the spatial and temporal evolution of flooding in complex urban environments. It explores the flood inundation characteristics under the combined scenario of extreme design rainstorms and river flooding. The results revealed that urban flood overflows are significantly affected by the rainfall return period, the location of the rain peak, and rainfall duration. The timing and severity of flood overflows were notably influenced by the location of the rainfall peak. The closer the peak occurs to the beginning of the storm, the greater the impact on the drainage system. When experiencing the impact of downstream river backflow, the load on the drainage network in the study area exceeded standard levels, resulting in a substantial increase in the extent of flooding. The number of grids with flood depths exceeding 0.6 m increased by 187.69% when a 50-year design rainfall was combined with the backflow of river flooding, compared to the 20-year rainfall combined with the design river flood scenario. Additionally, the construction of new pumping stations and floodgates can effectively mitigate urban flooding caused by river backflow. The study results provide technical support for urban flood prevention and mitigation in Zhoukou City.