The effect of Vetiver plant on runoff reduction and soil loss in parallel-convex and concave hillslopes in laboratory conditions

One of the important and effective factors in the runoff production and sediment in hillslopes is their geometry. Vegetation also plays an important role in controlling and reducing runoff and sediment. In this regard, the present study was conducted with the aim of creating a better understanding of the effect of Vetiver vegetation on the processes of runoff and soil loss in convex-parallel and concave-parallel hillslopes in laboratory conditions. Accordingly, by using a rainfall simulator with an intensity of 45 mm/h, in 15 min on a plot with dimensions of 2 m2 and a slope of 20 percent, and by creating the shape of convex-parallel and concave-parallel hillslopes and filled with the surface soil of the sample Tahooneh watershed in Yazd province, rainfall simulation was done. Then, the values of runoff volume and soil loss in the said plots were compared and data analysis was carried out in plots with Vetiver vegetation and in two square and rhombic planting patterns with plots without vegetation. The results showed a decrease in the runoff volume in the concave-parallel hillslope in the treatment with square and rhombic vegetation, with values of 58.61 percent and 69.43 percent, respectively. Also, the square and rhombic planting pattern of Vetiver plant in the convex-parallel hillslope caused a decrease of 81.17 percent and 85.96 percent in the amount of soil loss, respectively.