Effects of Grass Cover on the Overland Soil Erosion Mechanism Under Simulated Rainfall

Abstract Existing research on soil erosion primarily focuses on the individual effects of factors such as rainfall intensity, slope gradient, grass cover, and soil characteristics, with limited exploration of the interactions among these factors. This study investigated the mechanisms of soil erosion on overland covered with vegetation in the Loess Plateau region through indoor artificial simulated rainfall experiments. The experiments included six levels of grass coverage (0, 30%, 40%, 50%, 60%, 70%), five grass distribution patterns (DP, CP, VP, SP, HP), five rainfall intensities (60, 80, 90, 100, 120 mm/hr) and three slope gradients (5°, 10°, 15°) to explore the effects of experimental design factors and hydraulic parameters on the overland soil erosion mechanisms. The results show that as the grass coverage increases, the soil erosion rate on the overland decreases. Under different grass distribution patterns, horizontal grass distribution played an important role in inhibiting overland soil erosion rate. The overland soil erosion rate increased following a power function relationship with rising slope steepness and rainfall intensity, with erosion rates being more sensitive to changes in rainfall intensity than slope gradient. Among the six hydraulic parameters, dimensionless stream power was the optimal hydraulic parameters for predicting overland soil erosion rate under grass cover. Furthermore, an overland soil erosion model under the influence of grass cover and rainfall intensity was established based on general dimensionless hydraulic parameters ( KGE = 0.931, R 2 = 0.912). The model satisfactorily simulates overland soil erosion rate under grass cover and helps to reveal the mechanism of overland soil erosion.