Dynamic flood evacuation modelling for coastal cities: A case study of Shanghai

Efficient evacuation during storm floods remains a critical challenge for coastal cities, primarily due to its dynamic and complex nature of flood progression, human behavioral uncertainties, and emergency resource constraints. Current evacuation models inadequately capture these multifaceted dynamics, limiting effective emergency planning. This study introduces an Agent-based Dynamic Coastal Flood Evacuation (DCFE) model that comprehensively simulates the interactions among flood dynamics, human behavioral responses, GIS-based transportation networks, and shelter systems. Using Shanghai as a case study, we evaluate city-scale evacuations during a 1000-year return period storm event. Our results show that without early warning, only 24.2 % of affected populations successfully evacuate within 24 h. With 24-h advance warnings, the same number of people can be evacuated in just 9 h, preventing inundation for about 28 % of the population. Despite this improvement, overall evacuation success rates increase by only 11.2 % due to shelter capacity limitations. The results further reveal that optimized decision-making can double evacuation efficiency, while inequitable shelter distribution exacerbates spatial disparities in evacuation performance. This integrated approach provides practical guidelines for enhancing evacuation strategies in coastal megacities worldwide.