Mechanistic analysis of splash erosion on loess by single raindrop impact: Interaction of soil compaction, water content, and raindrop energy

Abstract

Theoretical and experimental studies have demonstrated that splash erosion on agricultural land can affect agricultural production and the ecosystem. However, the splash erosion process mechanism of loess erosion under the effects of a single raindrop remains unclear. Therefore, this study investigates the effects of single-raindrop splash erosion on the cohesion and internal friction angle of compacted loess under multiple compaction, water contents, and single-raindrop kinetic energies. The results showed that the depth and diameter of the crater were linearly related to both the raindrop kinetic energy and the loess compaction. The variation of crater depth is always lower than the variation of crater diameter, and the effect of the amount of raindrop energy on crater splash erosion is higher than the effect of the variation of compaction on crater splash erosion. Raindrops with higher kinetic energy have higher erosiveness, and this can shorten the ponding point time. When the water content is constant, the fitting curve of cohesion and compaction is the exponential relationship. The increment of cohesion decreases with increasing water content when the water content is lower than the optimum water content (12.7%) and increases with increasing water content when the water content is higher than the optimum water content. However, the increment of internal friction angle consistently increases with increasing water content, which is not affected by the optimum water content. This study could be a reference for soil erosion control in the Loess region.