Effects of rainfall intensity, slope angle, and vegetation coverage on the erosion characteristics of Pisha sandstone slopes under simulated rainfall conditions.

Abstract

The water loss and soil erosion in the Pisha sandstone region in the middle reaches of the Yellow River are extremely severe, leading to extremely harmful effects on the ecological environment and safety of the lower reaches. In this paper, the effects of the slope angle (20, 30, and 40°), rainfall intensity (20, 50, and 80mm/h), and vegetation coverage (10, 30, and 50%) on the erosion characteristics of the Pisha sandstone slopes are studied using indoor-simulated rainfall tests. The results show that the infiltration into the Pisha sandstone is only 10~15%. It is found that rainfall intensity has the most significant effect on runoff, which gradually increases with increasing rainfall intensity. Vegetation significantly affects runoff reduction when the rainfall intensity is low (approximately 20mm/h), but this effect decreases with increasing rainfall intensity. Rainfall intensity has an extremely significant effect (P < 0.01) on the sediment yield, followed by vegetation coverage, and slope angle. When the vegetation coverage is approximately 50%, the reduction in sediment yield reaches approximately 70%. Additionally, the sediment reduction benefit is more significant than the runoff reduction benefit. The presence of the eroded gullies on slopes with vegetation is less compared to that on the bare slopes. Therefore, relatively high vegetation coverage (≥ 50%) is required for soil and water conservation in Pisha sandstone area. The findings will provide some reference for Pisha sandstone conservation.