Assessing and Optimizing Flood Recovery Strategies for Road Network Disruptions in Shenzhen Based on Isochrone Analysis

Abstract The escalating threats of climate change and rapid urbanization to urban sustainability have intensified the urgency for effective flood recovery strategies, particularly regarding critical infrastructure such as road networks. Shenzhen, a megacity frequently hit by short-duration heavy rainfall and typhoon-induced storms, faces high flood risk that often causes severe road network disruption. This study proposes an integrated approach bridging flood simulation, loss assessment, and isochrone-based accessibility analysis to evaluate and mitigate flood impacts across the road network of Shenzhen City under various rainfall return periods. The flood simulation combines the Soil Conservation Service Curve Number (SCS-CN) model for runoff estimation with a DEM-based water accumulation algorithm. The results demonstrate that: (1) Increasing rainfall return periods lead to a progressive expansion of inundation areas, predominantly affecting commercial, educational, and industrial sectors, while road network loss based on the inundation depths escalates rapidly under a 10-year return period rainfall and stabilizes beyond the 20-year threshold; (2) Isochrone analysis reveals that accessibility to emergency centers undergoes accelerated decay for rainfall return periods shorter than 20 years, with the most pronounced degradation observed along the 4- to 6-min isochrones; (3) Post-disaster recovery strategies prioritizing isochrone decay directions outperform those based on road hierarchy, particularly in the 4-min critical zones. This research provides robust analytical tools and insights for identifying vulnerable road sections and nodes during flood events, facilitating the prioritization of road network recovery.