A Dynamic Urban Waterlogging Risk Assessment Framework Using RAGA-Optimized Projection Pursuit and Scenario Simulation

In response to escalating urban waterlogging crises exacerbated by global warming and accelerated urbanization, an innovative waterlogging risk assessment framework was advanced in this study to bolster urban resilience and promote sustainable urban development. Current methodologies often suffer from subjective bias in weight assignments for evaluation indicators. To overcome this limitation, the projection pursuit (PP) technique was integrated with a real-coded accelerated genetic algorithm (RAGA) to derive objective indicator weights. Focusing on the built-up area of Xiushan County in Chongqing, the InfoWorks ICM was employed to develop a 1D-2D coupled hydrodynamic model for simulating the dynamic spatiotemporal evolution of waterlogging events. Based on three dimensions namely hazard, sensitivity, and vulnerability, an urban waterlogging risk assessment model was developed and ArcGIS was utilized to precisely generate risk distribution maps under rainfall scenarios with return periods of 20 years and 100 years. Additionally, to enhance flood mitigation capabilities in identified high-risk zones, this study proposed implementing stormwater storage tank systems. Simulation results demonstrated that these measures achieve a 50.88% reduction in overflow volumes in critical areas, effectively lowering peak waterlogging depth from 0.74 m to 0.53 m. Key findings revealed that high-risk areas exhibit significant spatial clustering in low-elevation districts characterized by high population density and economic development intensity, where extreme rainfall events amplify water accumulation vulnerabilities, highlighting the importance of sustainable land use planning and climate adaptation strategies. The proposed assessment methodology not only enables objective quantification of urban waterlogging risks but also facilitates evidence-based formulation of targeted mitigation strategies, facilitating the goals of urban sustainability and long-term environmental resilience.