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    基于多源卫星数据的黄河中游降雨侵蚀力时空分异特征

    Spatiotemporal differentiation variation characteristics of rainfall erosivity in the middle reaches of the Yellow River basin based on multi-source satellite data

    • 摘要: 背景传统降雨侵蚀力研究多依赖地面气象站点数据,但受限于站点分布密度和数据连续性,难以满足复杂地形区大范围、高精度的实时监测需求,亟需借助时空覆盖能力更强、数据连续性更优的卫星降水产品。方法本文基于GPM IMERG与CMORPH卫星降水数据,以高密度站点网格降雨侵蚀力数据为基准,采用逐网格校正方法生成黄河中游2001—2020年降雨侵蚀力数据,分析其时空变化特征的差异性。结果 CMORPH卫星数据对黄河中游降雨侵蚀力的估算明显高于GPM IMERG,前者多年平均降雨侵蚀力数值是后者的1.3倍。空间分布上,GPM IMERG高值区位于北洛河和泾河,而CMORPH高值区范围更广。网格校正系数结果表明,GPM IMERG低估黄河中游57.4%区域的降雨侵蚀力,低估区主要分布在黄河中游核心产沙区;而CMORPH则高估75.8%区域的降雨侵蚀力,网格校正系数可为基于卫星降水数据的降雨侵蚀力实时反演和监测提供关键支撑。卫星数据校正后的结果表明,黄河中游2001—2020年降雨侵蚀力整体呈显著上升趋势,基于GPM IMERG与CMORPH的降雨侵蚀力增长率分别为11.2与12.7 MJ·mm/(hm2·h·a2),空间分布上,CMORPH显著上升的网格数量是GPM IMERG的1.6倍。不同子流域之间降雨侵蚀力差异明显,沁河流域降雨侵蚀力均值最高,汾河流域与河龙区间降雨侵蚀力显著上升,年际变化率显著高于其他子流域。结论研究结果可为黄河中游水土流失动态监测和防治措施优化配置提供科学依据。

       

      Abstract: Background Traditional research on rainfall erosivity has largely depended on the data from ground‑based meteorological stations. However, the limited spatial density of these stations and discontinuous records hinder high-resolution and real-time monitoring of rainfall erosivity over large, topographically complex areas. Consequently, there is an urgent need to utilize satellite precipitation products, which offer superior spatiotemporal coverage and data continuity, to evaluate changes in rainfall erosivity. Methods Based on GPM IMERG and CMORPH satellite precipitation data, and using grid rainfall erosivity data from high-density stations as a benchmark, this study employed a grid-by-grid correction method to generate the rainfall erosivity data for the middle reaches of the Yellow River basin from 2001 to 2020. Then the differences in its temporal and spatial variation characteristics were analyzed. Results The results showed that the CMORPH satellite data estimated the rainfall erosivity significantly higher than GPM IMERG in the middle reaches of the Yellow River basin. The average rainfall erosivity value estimated by CMORPH over the study period was 1.3 times that of GPM IMERG. Spatially, high rainfall erosivity values from GPM IMERG were located in the Beiluo River and Jing River basins, while the high-value areas identified by CMORPH were more extensive. The grid correction coefficients indicated that GPM IMERG underestimated the rainfall erosivity in 57.4% of the area within the middle reaches of the Yellow River basin, and these underestimated areas were primarily concentrated in core sediment source areas in the middle reaches of the Yellow River basin. CMORPH, conversely, overestimated rainfall erosivity in 75.8% of the area. The derived grid correction coefficients can provide key support for real-time inversion and monitoring of rainfall erosivity using satellite precipitation data. Analysis of the satellite data after correction revealed a significant upward trend in rainfall erosivity in the middle reaches of the Yellow River from 2001 to 2020. The growth rates of rainfall erosivity based on GPM IMERG and CMORPH were 11.2 and 12.7 MJ·mm/(hm²·h·a²), respectively. The number of grids exhibiting significantly increased rainfall erosivity based on CMORPH was 1.6 times that of GPM IMERG. Rainfall erosivity varied significantly among sub-basins in the middle reaches of the Yellow River basin. The mean rainfall erosivity in the Qin River basin was the highest, and the rainfall erosivity in the Fen River basin and the mainstream from Hekou to Longmen increased significantly, with a significantly higher inter-annual variation rate than other sub-basins. Conclusions The research results provide a scientific basis for dynamic monitoring of soil and water loss and the optimization of prevention and control measures in the middle reaches of the Yellow River basin.

       

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