4. Conclusions

In this study, erosion and rill morphology for four soils in the Loess Plateau, China, were compared under different artificial conditions. Results indicated that soil erosion differences among SL, LL and ML were mainly caused by different rill erosion processes. Soil erosion rates recorded varying degrees of increase with rill erosion under the four soil types: SL recorded a sharp increase, LL recorded a strong increase, and ML and HL recorded slight increases. HL was the most prone to the occurrence of rills; SL, LL and ML are prone to the occurrence of rills under heavy rain. The development of rills under SL was mainly characterized by an increase in Wa and N; the development of rills under HL were mainly characterized by an increase of CDL, J and N. Rill development indices for LL and ML were between those of SL and HL. The sensitivity of rill parameters to rainfall intensity was in the order of: N > DS > J > Wa > CDL ≈ Ha, and sensitivity to slope was in the order of: Ha > Wa ≈ J > DS ≈ N > CDL. Soil properties may affect rill formation by changing the distribution of slope flow and the stability of soil particles being stripped and scoured. At the same time, soil properties may also affect the relationship between rill morphology, rainfall intensity and slope by changing soil structure stability; rill morphology enhances the difference of different types of soil erosion by changing the distribution of water flow between and within rills. In addition, an empirical relationship based on soil characteristic factors, rill shape parameters and soil erosion were established to reflect the influence of soil characteristics and rill shape on soil erosion. These results improve our understanding of the effects of soil properties on soil erosion and rill morphology in the Loess Plateau.