Pluvial flood risk assessment for metro systems in the Guangdong-Hong Kong-Macao Greater Bay Area

Abstract

Urban pluvial floods are attracting growing concern due to rising intense precipitation and increasing consequences, particularly for underground transit networks. Accurate risk assessment is critical to efficient urban pluvial flood management. This paper describes an integrated methodology to evaluate the potential impact and risk of pluvial flooding on major metro systems in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). We use a high-resolution hydrodynamic model (FloodMap-HydroInundation2D) coupled with complex network analysis to simulate surface inundation and assess topological vulnerability under 10-, 50-, and 100-year rainfall return periods. Results suggest that the pluvial flood hazard increases non-linearly with escalating extreme rainfall, with Shenzhen and Hong Kong, China demonstrating the most pronounced hazard levels. Spatially, medium- and high-risk stations are predominantly concentrated in the central urban districts. As the flood hazard intensifies, the number of at-risk stations increases significantly, with the Guangzhou-Foshan Metro systems and the Shenzhen Metro system expanding most drastically. Network performance metrics of all metro systems deteriorate as the flood hazard escalates; the global network efficiency of the Guangzhou-Foshan Metro systems remains the lowest among all networks. The tested approach provides detailed flood information for the strategic management of urban underground transit networks. It can be widely applied to other megacities to support sustainable climate adaptation.

Graphical abstract

Keywords

pluvial flood / FloodMap-HydroInundation2D / metro network / risk analysis / climate change

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