Spatiotemporal evolution patterns of flood-causing rainstorm events in China from a 3D perspective

Floods induced by rainstorm events (RSEs) are among the most frequent natural disasters and have a significant impact on ecosystems and human society. While most extensive researches have investigated the magnitude, frequency, and risk of floods, understanding the spatiotemporal evolution of contiguous flood-causing rainstorm events remains largely unexplored in China. Here, we collected historical flood disaster data from the Statistical Yearbook, news reports, and government sources and examined the evolution patterns of spatiotemporally contiguous flood-causing RSEs across China from 2000 to 2020, utilizing the connected component three-dimensional algorithm. Our results indicate that floods mostly occur in southern China (SC), followed by northern China (NC), with less frequency in northwestern China (NWC) and the Qinghai-Tibetan Plateau (TP). The flood-causing RSEs tend to occur with longer durations and higher magnitudes in SC and NC, while in NWC and TP, they are primarily characterized by short-term precipitation processes with lower magnitudes. Moreover, the flood-causing RSEs exhibit distinct evolutionary patterns in different subregions. In NWC and TP, RSEs generally move eastward and southeastward, with relatively longer lifespans, traveling longer distances at faster moving speeds, but covering smaller areal extent and lower accumulated rainfall amounts. In contrast, in both SC and NC, flood-causing rainstorm events are mainly moved in two directions, namely westwards and eastwards. These events have shorter average lifespans, and travel shorter moving distances at slower moving speeds, but have a larger areal extent and huge accumulated rainfall amounts. Our findings significantly enhance our understanding of flood-causing rainstorm characteristics in China.