Comparison of the Effect of Vetiver Vegetation Cover and Surface Rock Fragment on Runoff and Soil loss in a Convex-Parallel Hillslope Under Laboratory Conditions

Given the importance of the geometry of hillslopes in producing runoff and sediment and the influence of soil surface cover on these two components, the present study was conducted to investigate the effect of Vetiver vegetation cover and surface rock fragment cover on a convex-parallel hillslope. After preparing the plot based on the geometry of the convex-parallel hillslope and transferring Vetiver vegetation cover and surface rock fragment cover with 30% coverage, rainfall simulation was performed, and the results showed that in this type of hillslope, surface rock fragment cover reduced the average volume of runoff by 13.6% compared to the control and reduced soil loss by 33.37%. In addition, Vetiver vegetation cover led to a 65.76% reduction in runoff volume and a 69.4% reduction in soil loss. Furthermore, the statistical results showed that the volume of runoff and soil loss in the convex-parallel hillslope in protective treatments were significantly different from the control (Pvalue <0.05), indicating that the addition of surface rock fragment cover and Vetiver vegetation cover reduces the volume and soil loss. These results demonstrate the positive effect of both covers on reducing runoff and sediment. Therefore, depending on the goal and the conditions of the study area, appropriate cover can be used.