Assessing the contribution of the sediment content and hydraulics parameters to the soil detachment rate using a flume scouring experiment

Rill erosion is one of the most important processes affecting soil detachment. Therefore, the quantification of the soil detachment process is important to establish a basic process-based erosion prediction model. The objective of this study was to assess the contributions of the hydraulics parameters and sediment content to the soil detachment rate of purple soil. Purple soil was collected from a typical hilly region in Sichuan, China. Six scouring experiments were conducted in two 1 m x 2 m boxes at six different flow discharge rates (2, 4, 6, 8, 10, and 12 L min(-1)) in an upslope drainage area (0.30 m(2)) with a 15 degrees slope. The results show that the soil detachment rate greatly changes during the rill development stage and the soil detachment rate varies at a sediment content of 0.15 g L-1. Furthermore, the soil detachment rate is negatively related to the sediment content. The relationships between the sediment content and hydraulics parameters can be described with a negative power function. The soil detachment rate is positively related to the stream power, the relationship can be described with a linear function. The comprehensive relationship between the soil detachment rate and sediment content and stream power can be described with a binary linear equation. The proportional contribution of the sediment content to the soil detachment rate is 80.65% and that of the stream power is 19.35%. The sediment content has a negative effect on the soil detachment rate in rills. The stream power has a positive effect; it induces soil detachment. The negative effect of the sediment content on the soil detachment rate is influenced by the stream power. This study provides new insights into the effects of the sediment content and hydraulics on the rill erosion process.