ABM-based emergency evacuation modelling during urban pluvial floods: A “7.20” pluvial flood event study in Zhengzhou, Henan Province

Increasing urban pluvial flood disasters due to climate change and rapid urbanisation have been a great challenge worldwide. Timely and effective emergency evacuation is important for reducing casualties and losses. This has become a bottleneck for emergency management. This study aimed to develop a commonly used Agent-Based Mode (ABM) for pluvial flood emergency evacuation at the city scale, exploring the cascading impacts of pluvial flooding on human behaviour and emergency evacuation. The July 2021 pluvial flood event in Zhengzhou, Henan Province, claiming 380 lives and 40.9 billion yuan in direct losses, was selected as this case study. A raster-based hydraulic model (ECNU Flood-Urban) was used to predict flood inundation (extent and depth) during an event in Zhengzhou’s centre. Moreover, a comparative analysis of emergency evacuations was conducted before and after the pluvial flood event. The results showed that crowd behaviour plays an important role in an emergency evacuation, and extensive flooding leads to an 11–83% reduction in the number of evacuees. This study highlights the importance of risk education and contingency plans in emergency response. The ABM model developed in this study is proven to be effective and practical and will provide support for decision-making in urban flood emergency management.