The analysis of urban flood risk propagation based on the modified susceptible infected recovered model

Increasing urban flood posed serious threat to urban safety and sustainable development, and resulted in great loss and damage. It was significant and indispensable to master the potential change of urban flood for flood risk mitigation and adaption. Floods not merely caused the physical losses, but also led to potential damage and harm during flood risk propagation. Studies have mainly focused on the physical features of flood risk and post-disaster reconstruction, while few have discussed the potential risk consequence considering flood risk propagation. Therefore, this study analyzed flood risk propagation based on modified Susceptible Infected Recovered (SIR) model. We performed flood simulation and modelling, mapped urban flood risk in consideration of flood risk propagation, and estimated flood losses in Nanjing with flood return periods of 5, 10, 20, 50, and 100 years. Results indicated that inundated area occupied 517.19, 654.11, 657.92, 834.49 and 1045.80 km2 with return periods from 5 to 100 years respectively. Jianye District showed high flood risk and it was suggested to protect people’s lives and assets to reduce susceptibility and vulnerability, and enhance urban drainage capacity for recovery improvement. Moreover, total economic losses reached $27.85, $30.89, $32.91, $35.50 and $38.55 billion and led to the 14.38%, 15.94%, 15.94%, 18.32% and 19.90% GDP loss rate respectively. This study could support the effective flood risk mitigation practice for adaptive urban development.