Future Projection of Rainstorm and Flood Disaster Risk in Southwest China Based on CMIP6 Models

Under the background of global warming and frequent extreme weather and climate events, the occurrence of rainstorm and flood disasters in Southwest China continues to increase, causing great losses to social economy and people's lives and property. In order to project the characteristics of future rainstorm and flood disaster risk in Southwest China, 5 CMIP6 models and 5 extreme precipitation indices are selected to construct a risk assessment model, combined with topographic factors, socio-economic data and percentage of cultivated land area, by comprehensively considering disastrous factors and vulnerability. The rainstorm and flood disaster risks are mainly assessed for the baseline period (1995-2014), projected under three scenarios (SSP1-2.6, SSP2-4.5, SSP5-8.5) for two future periods (2021-2040, 2041-2060), and comparatively analyzed. The results show that the simulation performance of EC-Earth3 and EC-Earth3-Veg on the selected 5 extreme precipitation indices is excellent, and the performance of un-equal weighted aggregation (UEWA-5) is better than equal weighted aggregation (EWA-5). According to the prediction results, 5 extreme precipitation indices are high in western Yunnan, northeastern Guangxi, and the western margin of Sichuan Basin. Higher social vulnerability and radiation forcing lead to greater extreme precipitation index. From the baseline period to the next two periods, the extreme precipitation indices and risk of disastrous factors show an increasing trend. The high vulnerability areas are distributed in the economically and agriculturally developed regional central cities and the change of vulnerability is not obvious under different scenarios. The medium-high risk areas and high risk areas of rainstorm and flood disasters are mainly distributed in Chengdu City of Sichuan, the center of Chongqing and western Sichuan Basin, Kunming City of Yunnan, Guilin City and south-central parts of Guangxi. The medium-high risk areas and high risk areas in Southwest China increase with time from the base period to the far future, especially under the SSP2-4.5 scenario.