Flood Impact on Urban Mobility: An Assessment of Subway Infrastructure Vulnerability in China

In recent years, the increased frequency and severity of extreme weather events, especially flooding, have drawn urgent attention to the associated risks and consequences. Flooding is a major concern due to its potential to cause significant damage to infrastructure, property, and public health. The impact of flooding on transportation and safety can be severe, as it may obstruct roads, disrupt daily travel and commuting, and even cause internal power outages and service suspensions in subway systems, posing a significant challenge to urban transportation. This study focuses on analyzing the potential damage to subway stations in China using flood hazard maps with different return periods. To identify the core stations or transit hubs with high influence, we utilized the subway station network to determine the top 10% of stations with the highest eigenvector centrality. We then divided the urban population based on their proximity to the nearest subway stations, using the population distribution map. This allowed us to measure the distribution of passenger volume within the urban area's subway system and floodplain. To assess the vulnerability of the core stations, we calculated the transportation facility damage percentage with flood hazard map depth. This helped us identify the most vulnerable core stations, as well as those with the highest influence. Finally, we estimated the total value lost in the flooding area by calculating the damage value of China's transportation facilities. These results allowed us to assess standards for subway flood protection, ensuring that the impact on urban subway infrastructure during flood events is minimized, thereby facilitating people's travel and daily lives.