Mechanism Analysis of the Effects of Rainfall Intensity, Grass Coverage, and Slope on Slope Erosion Processes

Rainfall intensity, grass coverage, and slope are key factors controlling runoff and soil erosion processes. However, the coupled analysis and interactive effects of erosion factors under vegetation influence remain at the stage of mechanistic exploration and qualitative research. This study conducted artificial rainfall simulation experiments to compare and analyze runoff and sediment yield patterns on loess slopes to address this issue. The results showed that the impact of rainfall intensity, grass coverage, and slope on total runoff and sediment yield on slopes is the result of multiple factors acting together. The contribution rate of rainfall intensity to the 15 min runoff yield and total runoff yield during different rainfall periods ranged from 56.40% to 94.87% and 58.36% to 77.87%, respectively. The contribution rate of rainfall intensity to the 15 min sediment yield and total sediment yield ranged from 29.62% to 90.92% and 41.81% to 55.07%, respectively. The effect of slope on runoff and sediment yield variation was relatively smaller. The contribution rate of slope to the 15 min runoff yield and total runoff yield ranged from 0.99% to 21.36% and 0.52% to 13.54%, respectively, while its contribution rate to the 15 min sediment yield and total sediment yield ranged from 1.73% to 36.05% and 10.10% to 16.34%, respectively. For grass coverage of 0% and 30%, runoff was primarily controlled by rainfall intensity and slope, whereas for 40% and 50% grass coverage, runoff was mainly influenced by rainfall intensity. For grass coverage of 0%, 30%, and 40%, sediment yield was primarily controlled by rainfall intensity and slope, while for 50% grass coverage, sediment yield was influenced by rainfall intensity, slope, and the rainfall intensity–slope interaction.