Coupling Waterlogging Hazard Assessment Based on <scp>SWMM</scp> – <scp>LISFLOOD</scp> Simulation in Chaoyang River Basin of Nanning, China

ABSTRACT Urban stormwater waterlogging poses significant threats to public safety and property, making scientific and effective risk management a crucial element in China's whole‐area sponge city construction. This study evaluates waterlogging hazards in Nanning's Chaoyang River Basin using a SWMM–LISFLOOD coupled model to simulate 11 design storm scenarios (0.25–100‐year return periods). A multicriteria decision analysis (MCDA) method integrating six hazard indicators (inundation depth, inundation duration, inundation area, elevation, slope, and land use) was employed through a game theory‐optimized composite weighting method combining AHP and CRITIC approaches. The results indicate that the waterlogging simulation outcomes align well with the actual conditions. The risk contributions of urban waterlogging hazard factors are generally higher than those of underlying surface disaster‐predisposing environmental factors, with inundation depth exhibiting the highest risk contribution (weight: 0.405). The coupling waterlogging hazards across different storm scenarios in the study area exhibited significant spatial heterogeneity. Spatial hazard patterns transition from Low and Negligible Risk under 0.25–2‐year storms to Moderate and High Risk dominance at 20–100‐year scenarios. This study achieved coupled waterlogging hazard zoning mapping at a 12.5 m spatial resolution across the study area, providing critical scientific support for the sustainable development of systematic and whole‐area sponge city construction in Nanning City, as well as for waterlogging hazard early warning systems and contingency planning.