More extreme precipitation over the Yangtze River Basin, China: Insights from historical and projected perspectives

Detecting and predicting extreme weather events are important for the risk management, human health and social economy. Here, we comprehensively investigate the historical and projected variations of extreme precipitation events in the Yangtze River Basin (YRB) using the observational data and the multi-model ensemble data under SSP245 and SSP585 scenarios provided by the newest round of the Coupled Model Inter-comparison Project phase 6 (CMIP6). Five extreme precipitation indices including RX1-day, RX5-day, R50mm, SDII, and R95pTOT are analyzed in this study. The observational results reveal that all extreme precipitation indices (except for RX5-day) show significant positive trends during 1961–2017. Spatially, the trends of extreme precipitation vary across the YRB, and the greater upward trends are observed in the eastern YRB (except for R50mm). The results from model simulations indicate that extreme precipitation events during 2023–2100 are projected to increase significantly relative to that in the reference period (1986–2005), and the average increase of the five extreme precipitation indices over the whole region reach approximately 20 and 35% under the SSP245 and SSP585 scenarios, respectively. Similar spatial distributions between SSP245 and SSP585 are observed, with more pronounced increases of the projected changes in the central and eastern YRB. Notably, the population exposure to extreme precipitation is also assessed and the results reveal that it would increase by nearly 4 × 108 people even though the population is projected to reduce sharply in the future. This study provides a comprehensive understanding of the historical and projected extreme precipitation variation across the YRB based on a series of analysis method, which is an important reference for the risk management and development of mitigation strategies.