Risk assessment of individuals exposed to urban floods

Risk assessment of individuals in urban flooding events requires quantitative criteria of human instabilities and hazard identifications. The existing guidelines might not be representative of some inundation situations in urban settings without considering the risks associated with human behaviors. Current guidelines may be under or over-estimated to be applied during a natural urban flooding disaster. This work proposes a hybrid model by coupling an efficient hydrody-namic model with a physics-based model to quantify individuals' instabilities in urban flood events, both children and adults, based on the flow regimes and human physical characteristics. The model accounts for human behavior and the failure mechanism caused by physical in-stabilities of toppling, sliding, and drowning. The hazard degree is identified in terms of flow velocity and water depth in floodwaters. The hydrodynamic model is calibrated in a densely urbanized area in the city of the UK and the instabilities threshold curves for adults and children are validated using existing measurements in the literature. Applications of extreme precipitation events that occurred in Wuhan city of China showed that adults are relatively safe in most of the study sites with a low hazard except in the areas where the flood water depth exceeds the low limit of hazard criteria. However, the distribution of flood hazard degrees for children is signif-icantly increased compared to that for adults. Furthermore, hazardous zones were observed in the vicinity of critical facilities such as the government house, supermarket, hospital, metro station, and primary school, consistent with the deep flood depth distribution. Overall, this work develops a hybrid model for risk assessment of individuals exposed to urban floods and the hazard criteria that could be implemented in urban flood risk management for sustainable cities.