Assessments of changes of extreme climate events along the Beijing-Hangzhou Grand Canal

The Beijing-Hangzhou Grand Canal carries unique social, cultural and ecological significance as a world cultural heritage, but it has potentially severe flood risks under extreme weather events with climate change. Therefore, to protect the ecological and cultural values of the Grand Canal, it is necessary to assess changes of extreme climate events along the Grand Canal areas. We used the latest Coupled Model Intercomparison Project (CMIP), CMIP6, to predict changes of extreme climate events along the Grand Canal in the past and future, by using multimodal ensemble data under historical, SSP245, and SSP585 scenarios. The overall trend of extreme precipitation in the Grand Canal region is greater in the future than that in historical periods, with greater differences in the SSP585 scenario. The impact range of extreme precipitation in 58 heritage sites of the Grand Canal during historical periods is 17%; while the impact range of extreme precipitation in SSP245 is 64%, and in SSP585 is 71%. Compared to SSP585, SSP245 can avoid extreme precipitation levels. If climate change is SSP245, the average extreme precipitation in the Grand Canal can be reduced by 15% in the next 100 years. The regions with high coefficient of variation are mainly concentrated in Shandong, Henan, and Jiangsu regions involved in the Grand Canal, with Henan having the greatest uncertainty. This indicates that the extreme precipitation results in these regions are uncertain, and the uncertainty in high emission scenarios is greater, requiring further research.