Spatiotemporal patterns and zonation of typhoon and non-typhoon extreme rainfall hazards in the typical coastal region of southeastern China

To enhance extreme rainfall risk assessment in East Asia, it is critical to distinguish typhoon and non-typhoon rainfall, assessing the spatiotemporal patterns of their extreme rainfall hazards and conducting corresponding spatial zonation. Taking Fujian, China’s southeastern coast, as a typical case, three extreme rainfall indices and a combined weighting method of entropy weight and an analytic hierarchy process were used to analyze the spatiotemporal patterns of typhoon extreme rainfall and non-typhoon extreme rainfall hazards, followed by spatial zonation based on their spatial differences. The results showed remarkable spatiotemporal heterogeneity in these two types of hazards in Fujian. Temporally, the non-TER hazard was generally higher, with the average hazard being 0.193 and peaking in June. In contrast, the TER hazard occurred primarily from July to September, with an average of 0.156 and a peak in August. Spatially, the TER hazard exhibited greater heterogeneity, increasing from the western inland region to the eastern coast, whereas the non-TER hazard displayed the opposite pattern. Fujian can be divided into three zones of extreme rainfall hazard: non-typhoon-dominated zone, typhoon-dominated zone, and typhoon and non-typhoon co-dominated zone. This study provides a newer perspective for extreme rainfall hazard assessment in East Asia and offers targeted guidance for disaster prevention and mitigation.