Variation characteristics and effects of splash erosion on slope micro-relief in bare fields

In order to determine the effect of migration distance on the abrasion degree of red soil aggregate in different layer in overland flow, the relationship between aggregate stability of red soil in different layer and abrasion degree was studied based on the analysis of aggregate stability and the simulated scouring experiment in laboratory. Red soils from three areas (Xianning, Jinxian and Changsha city) were chosen for this study. The results showed that the aggregate stability of red soils from wetting sieving and LB methods (fast-wetting and stirring pre-wetted) was the greatest for iron-manganese illuvial layer, intermediate for reticulated mottling layer and least for the surface soil layer in the three areas. However, the slow-wetting treatment had no significant regularity between the different layers in this study. The main mechanisms of aggregate breakdown in different layers were slaking and mechanical breakdown. The abrasion degree of aggregate in different layers was iron-manganese illuvial layer < reticulated mottling layer < surface soil layer in five migration distances. The parameter RMI which describes mechanical breakdown showed a significant correlation with the abrasion degree and abrasion coefficient α. By introducing the parameter RMI and transport distance x, the abrasion degree prediction equation of red soil aggregate in different layer was established with a good correlation coefficient (R2= 0.88). The equation showed a good prediction performance. The results can provide a reference for research on erosion mechanisms of red soil, which is of great significance for the development of adequate soil erosion models.