Research on Urban Flooding Simulation and Drainage Capacity Enhancement in Typical Southern Hilly Cities

To address the challenges posed by insufficiently understood of flood evolution and causal mechanisms,as well as the limited effectiveness of conventional mitigation measures in southern hilly cities,this study took an urban district in a hilly city of Jiangxi Province as a case.A dynamically coupled “1D drainage network-2D surface” model was developed using the MIKE FLOOD platform,the evolution process and inundation characteristics of urban flooding in hilly cities was accurately simulated to reveal the causal mechanisms.A “high-medium-low three-level control and multi-level linkage” flood prevention measures was proposed for hilly cities.The measures involve clearing drainage channels in high-lying areas,upgrading insufficient drainage pipelines in medium-altitude areas,and expanding the drainage pipelines in flood-prone low-lying areas.The results indicate that the coupled model achieves relative errors of 1.76%~17.4% in simulating water inundation depth when compared with field measurements.Under a 20-year return period rainstorm scenario,the area affected by water accumulation accounts for 12.4%,and the maximum water depth reaches 1.80m.The proposed flood control measures effectively overcome the terrain height differences,hardened surface conditions and the limitations of engineering measures such as poor drainage system connectivity and inadequate rainwater absorption measures.The waterlogged area in the study area reduces by 82.1%,and the flood area with a depth exceeding 0.5m decreases by 86.2%.It can significantly enhance the drainage capacity in the study area,and better address the urban flooding problems in hilly cities during rainstorm scenarios.