Multidimensional Flood Risk Analysis of High-Speed Rail Systems Under Future Climate Change

Flood hazards intensified by global warming pose a severe threat to global infrastructure, including the high-speed rail (HSR) system. However, future climate impacts on HSR remain underexplored. This study presents an integrated framework for comprehensively analyzing HSR flood risks under climate change. First, we developed a three-layer HSR model to evaluate HSR performance across the topological, functional, and service dimensions. Subsequently, we simulated future flood scenarios using the CaMa-Flood model to generate flood events with varying occurrence probabilities. By integrating HSR performance losses under these flood conditions with their occurrence probabilities, we assessed the HSR flood risks and identified key influencing factors through a multifactor correlation analysis. The results predicted a considerable rise in flood risk for Chinese HSR by the late 21st century, especially in the function and service dimensions, with 12%-35% and 12%-33% increase, respectively, compared with historical baselines. We also observed significant heterogeneity in flood risk among provinces; the situation is projected to deteriorate over time. However, areas with higher socioeconomic levels and operational capacity experience lower flood risk. Furthermore, a cost-benefit analysis of varied maintenance strategies revealed that a risk-based maintenance strategy (RMS), considering both track failure probability and criticality, exhibits better efficiency than other strategies, achieving the highest average risk mitigation effect (0.02) per 1000 km of maintenance track. These insights offer a multidimensional and multiscale understanding of the HSR flood risk under climate change and provide practical guidance for climate-resilient infrastructure development and maintenance planning.