Spatiotemporal Evolution of Extreme Rainstorm Events in China and Corresponding Population Exposure

ABSTRACT: In order to reveal the spatio-temporal evolution of extreme rainstorm events in China and the changing characteristics of population exposure in different periods, this study systematically explored the spatio-temporal evolution characteristics of four indicators of extreme rainstorm frequency, duration, peak and cumulative amount, as well as the difference of population exposure to extreme rainstorm events in 2000 and 2020, based on the relevant data of extreme rainstorm and population distribution grid data from 2000 to 2020, using spatial analysis and trend analysis methods. The results show that in space, the frequency, peak value, and cumulative amount of extreme rainstorms are increasing from northwest to southeast, the southeast coast is a high value area, and there is almost no extreme rainstorm in the northwest arid area; The high-value areas of duration are concentrated in the Qinghai Tibet Plateau and Northeast China. In terms of time, from 2000 to 2020, the frequency of extreme rainstorm in Northeast China increased, the southern part of the Qinghai Tibet Plateau and other regions decreased, the peak value of rainstorm in North China Plain and the eastern coast increased, Taiwan Province showed a significant downward trend, and the change rate of rainstorm accumulation was stronger in the south and weaker in the north. In terms of spatial concentration, the high value concentration area of extreme rainstorms generally shifts to South China, while the low value concentration area is stably distributed in the northwest and part of the north. In terms of population exposure, the distribution characteristics of 2000 and 2020 are low in the northwest and high in the southeast, and the exposure of capital cities in southeast coastal provinces to extreme rainstorm frequency and peak in 2020 is significantly higher than that in 2000. Population migration and the evolution of extreme rainstorm events are the main driving factors. This study clarifies the temporal and spatial evolution law of extreme rainstorm events in China and the characteristics of population exposure change, which provides a scientific basis for regional extreme rainstorm disaster risk assessment, disaster prevention and mitigation planning, and optimization of population and urban development layout, and has important practical significance for improving the ability to respond to extreme climate events and ensuring regional population security and sustainable development.