Comparison of impact and water vapor characteristics between two types of floods in Eastern China

Floods are one of the most devastating natural hazards, resulting in social and economic losses. As a flood-prone area, East China (EC) suffers floods mainly related to monsoons and tropical cyclones (TC). However, how the floods induced by heavy rain (HR) and TC impact on human life, and what their differences are, is not yet clear. In this paper, we assess the spatiotemporal characteristics of two types of floods in South China (SC), the middle and low reaches of the Yangtze River (YHR), and North China (NC) for 1985–2020, and investigate the impacts on human mortality and displacement. Furthermore, we use the improved areal source-receptor attribution method to quantify the water vapor contribution from each moisture source. Results show that HR-induced floods occur more frequently than TC-induced floods in three study areas for 1985–2020. The spatial pattern of the severity of floods exhibits an increasing gradient from North to South. The trends of annual mean mortality and displacement rates were significantly decreasing over time. The most important moisture sources for HR-induced floods in three study regions are all from EC. Contributions account for 26.6%, 45.0% and 54.5% in SC, YHR and NC, respectively. However, the most important moisture source for TC-induced floods in SC and YHR is from the Western Pacific Ocean. Contributions account for 21.9% and 44.3% in SC and YHR, respectively. The above result within the Lagrangian framework is well confirmed by the Eulerian framework.