Evaluating the influence of human activities on flood severity and its spatial heterogeneity across the Pearl River Delta.

With climate change and intensified human activities, disasters such as heavy rainfall, flooding, typhoons, and storm surges are becoming more frequent, posing significant threats to lives, property, and economic development. We propose a method combining extreme value theory and probability distribution to examine the flood severity under the effect of strong human activities. By focusing on the Pearl River Delta (PRD), as one of the most populated areas of China, we quantified changes in the severity of extreme water level for different return levels between 1966 and 1990 and 1991-2016 (with strong human activities), associated with the spatial patterns over the PRD. The flood severity decreased near inland areas of the delta but increased in coastal areas. Additionally, in coastal areas, the flood severity of long return levels has increased more significantly than that of short return levels, under the effect of strong anthropogenic activities. This study further examined the spatial heterogeneity in extreme water levels under the influence of human activities over the PRD. This study provides new insights into basin-scale flood responses to human activities and strategies for mitigating flood disasters over the PRD. The proposed method offers a promising approach for evaluating the severity of flooding in regions experiencing hydrological changes similar to those observed in the PRD under the influence of human intervention.