近40年黄河流域(河南段)降水时空演变特征及未来趋势预估
Spatiotemporal patterns and future projections of precipitation in the Henan section of the Yellow River Basin over the past 40 years
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摘要: 以黄河流域中下游过渡带(河南段)为研究对象,基于1981—2020年高分辨率降尺度栅格降水数据,综合运用Morlet小波、经验正交函数(Empirical orthogonal function,EOF)分解及标准化降水指数(Standardized precipitation index,SPI)等方法,系统揭示了区域降水的时空演变与旱涝特征,并结合CMIP6模式预估SSP2-4.5与SSP5-8.5情景下未来30 a的降水变化趋势。结果表明:1981—2020年,研究区年降水量及除春季外的各季节降水量呈不显著的增加趋势;空间分布呈“南多北少”格局,且受地形明显调控;EOF分析表明,降水变率以全区一致型为主导模态,同时存在东西反向差异及局地复杂分异;SPI显示中西部春、夏季干旱化趋势显著,旱涝事件交替频繁。未来情景预估显示,在两种排放情景下“南多北少”的空间格局将持续,且随辐射强迫增强,南北降水差异进一步扩大,极端降水风险可能升高。基于此,建议结合区域降水时空分异特征优化水资源配置,并依据旱涝演变趋势提升农业气候适应性与防灾减灾能力。Abstract: 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.
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