关键词: 风险评估, 洪涝灾害, 层次分析法, 熵权法, 临港新片区

Abstract:

[Objective] Flood disaster risk assessment for coastal cities is crucial for improving the resilience of new urban planning and disaster emergency management capabilities. This study focuses on the issues in existing research on flood risk assessment in coastal new towns, such as incomplete indicator systems and insufficient spatial analysis accuracy. Taking Lingang New City in Shanghai as the study area, this study conducted a detailed comprehensive flood disaster risk assessment to provide a scientific basis and decision support for disaster risk management, emergency response, and urban planning. [Methods] Following the principles of scientific rigor and operability, a three-dimensional assessment model was established integrating the hazard of disaster-inducing factors, the exposure of disaster-prone environments, and the vulnerability of disaster-bearing bodies. A high-resolution grid unit of 30m × 30m was innovatively adopted, and a combined subjective-objective weighting approach was used by integrating the Analytic Hierarchy Process (AHP) and the entropy weight method. Through spatial overlay analysis, a refined flood disaster risk assessment was achieved. [Results] (1) Hazard distribution: Due to the limited and relatively uniform distribution of rainfall sampling points, rainfall indicators in the study area were regarded as homogeneously distributed. Therefore, the spatial variation in the hazard of disaster-inducing factors was mainly determined by river network density. (2) Exposure distribution: High and relatively high exposure areas were mainly located near towns and streets, where the proportion of impervious surfaces was high, and both vegetation coverage and terrain elevation were relatively low. Low and relatively low exposure areas were widely distributed in suburban and rural areas. (3) Vulnerability distribution: High and relatively high vulnerability areas were concentrated in Pudong New Area, especially around Nicheng Town and Dishui Lake, where GDP per unit area and population density were relatively high. Fengxian District showed comparatively lower vulnerability. (4) Comprehensive risk distribution: The spatial distribution of comprehensive flood risk levels in Lingang New Area was relatively balanced, with high-risk areas accounting for 10.34%, relatively high-risk areas 17.97%, medium-risk areas 27.59%, relatively low-risk areas 27.03%, and low-risk areas 17.07%. Spatially, there were significant regional disparities. The southeastern coastal region (e.g., Nanhui New Town and its surroundings) had the highest risk, followed by central town areas (e.g., Nicheng Town, Shuyuan Town), while the central-western rural areas had the lowest risk. [Conclusion] The proposed “three-dimensional nine-indicator” assessment framework overcomes the limitation of separating subjective and objective weights in traditional risk assessments. The constructed flood risk indicator system can provide a replicable risk governance paradigm for China and other rapidly developing coastal cities.

Key words: risk assessment, flood disaster, analytic hierarchy process, entropy weight method, Lingang New Area