Spatiotemporal patterns and future projections of precipitation in the Henan section of the Yellow River Basin over the past 40 years

The middle-lower Yellow River transition zone （Henan section） was taken as the research object. Based on high-resolution downscaled gridded precipitation data from 1981 to 2020， the methods such as the Morlet wavelet analysis， the empirical orthogonal function （EOF） decomposition， and the standardized precipitation index （SPI） were comprehensively applied to systematically reveal the spatiotemporal evolution and drought-flood characteristics of regional precipitation. Combined with CMIP6 model projections， future precipitation trends under the SSP2-4.5 and SSP5-8.5 scenarios for the next 30 years were also estimated. The results indicated that， from 1981 to 2020， annual precipitation and seasonal precipitation （except in spring） showed a non-significant increasing trend in the study area. Spatially， precipitation presented a pattern of "more in the south， less in the north" which was noticeably influenced by topography. EOF analysis revealed that the dominant mode of precipitation variability was a uniform pattern across the region， accompanied by east-west opposite anomalies and localized complex variations. The SPI indicated a significant drying trend in spring and summer in the central-western part of the region， with frequent alternations between drought and flood events. Future scenario projections suggested that the "more in the south， less in the north" spatial pattern would persist under both emission scenarios， and the north-south precipitation contrast was expected to intensify with increasing radiative forcing， potentially elevating the risk of extreme precipitation events. Accordingly， it is recommended to optimize water resource allocation based on the spatiotemporal heterogeneity of regional precipitation and to enhance agricultural climate resilience and disaster prevention and mitigation capacities in line with drought-flood evolution trends.