Response of erosive rainfall thresholds on Loess slopes to land cover and rainfall intensity

Rainfall events of sufficient intensity can trigger soil erosion on loess hillslopes. Determining the actual threshold of erosive rainfall events is essential for reducing the workload of soil erosion forecasting and for providing scientific guidance for soil erosion prevention. Based on long-term field observations from runoff plots in representative regions of the Loess Plateau, including Suide, Xifeng, and Tianshui, this study applied an improved regression analysis method to identify rainfall thresholds for soil erosion under different erosion intensities. The variation of rainfall thresholds with rainfall intensity was further examined, and a nonlinear regression approach was used to develop predictive models of rainfall thresholds for soil erosion under different land cover conditions. Rainfall thresholds for slope soil erosion under different land cover types decrease exponentially with increasing rainfall intensity. Influenced by soil texture, rainfall thresholds for soil erosion on woodland, grassland, and bare slopes declined as soil texture became finer, while the rate of decline slowed with increasing rainfall intensity. Soil texture, land cover type, and rainfall characteristics exert significant influences on the effectiveness of vegetation in controlling runoff and soil erosion. These findings provide valuable insights into soil erosion prediction and serve as a reference for soil and water conservation planning.