Assessment and Improvement of Emergency Rescue Service Accessibility under Urban Waterlogging Disasters

With the acceleration of urbanization and the impact of climate change, the frequent occurrence of urban waterlogging not only leads to road closures and traffic congestion but also severely affects the timeliness of urban emergency rescue. To accurately assess and enhance the response capability of urban emergency rescue under storm-induced waterlogging scenarios, a hydrodynamic model of urban waterlogging was developed to simulate waterlogging conditions under various design rainfall scenarios. By identifying road waterlogging risks and blocked roads, as well as combining the Two-Step Floating Catchment Area (2SFCA) method, the accessibility of emergency rescue services for points of interest (POIs) with different vulnerabilities was evaluated. The Liwan District of Guangzhou City was selected as a case study for accessibility impact assessment and improvement simulation. The results indicate that with the increase in the return period of rainfall, both the area and depth of waterlogged regions increased and the number of roads affected by waterlogging rose, leading to an increase in the length of blocked roads from 11 km to 49 km, an increase of over 300%. Additionally, the number of POIs inaccessible to emergency rescue increased, while the number of accessible POIs decreased, resulting in a significant downward trend in overall accessibility. By deploying mobile pumping vehicles, the depth and area of waterlogging under different rainfall return periods were reduced by over 10%, the number of blocked roads decreased by more than 10%, and the number of accessible POIs increased by more than 12%. The findings highlight that storm-induced waterlogging not only hinders traffic flow but also reduces the response capability of emergency rescue services. Through the strategic deployment of mobile pumping vehicles, the accessibility of urban emergency rescue services under waterlogging conditions can be effectively improved, mitigating the impact of waterlogging on urban functions and public safety.