Objective Traditional research on rainfall erosivity has largely depended on 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 identify the spatiotemporal differentiation characteristics of rainfall erosivity in the middle reaches of the Yellow River utilizing satellite precipitation products, which offer superior spatiotemporal coverage and data continuity.

Methods Based on 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 rainfall erosivity data for the middle reaches of the Yellow River Basin from 2001 to 2020. Then, the differences in its spatiotemporal variation characteristics were analyzed using the Theil-Sen slope estimator and Mann-Kendall trend test.

Results The CMORPH satellite data estimated rainfall erosivity significantly higher than IMERG in the middle reaches of the Yellow River. The average rainfall erosivity value estimated by CMORPH over the study period was 1.3 times that of the IMERG. Spatially, the high-value areas of IMERG were located in the Beiluo River Basin and Jing River Basin, while the high-value areas of CMORPH were more extensive. The results of the grid-scale correction coefficients indicated that IMERG underestimated rainfall erosivity in 57.4% of the area within the middle reaches of the Yellow River, and these underestimated areas were primarily concentrated in core sediment-producing areas in the middle reaches of the Yellow River. CMORPH, conversely, overestimated rainfall erosivity in 75.8% of the area. The derived grid correction coefficients could provide key support for real-time inversion and monitoring of rainfall erosivity using satellite precipitation data.

Conclusions A significant upward trend in rainfall erosivity in the middle reaches of the Yellow River from 2001 to 2020 is identified. The growth rates of rainfall erosivity based on IMERG and CMORPH are 11.2 and 12.7 MJ·mm/(hm²·h·a), respectively. The number of grids exhibiting significantly increased rainfall erosivity based on CMORPH is 1.6 times that of IMERG. Rainfall erosivity varies significantly among different sub-basins in the middle reaches of the Yellow River Basin. The average rainfall erosivity in the Qin River Basin is the highest, and the rainfall erosivity in the Fen River Basin and the mainstream from Hekou to Longmen increases significantly, with a significantly higher interannual change rate than that of other sub-basins. The research results provide a scientific basis for the dynamic monitoring of soil and water loss and the optimal allocation of prevention and control measures in the middle reaches of the Yellow River.