The effects of slope shapes on soil erosion

In this study, the effect of slope shapes on erosion has been studied for two years by using runoff plots under natural rainfall events. A sum of 18 runoff plots were set up on uniform, concave and convex hillslopes, 6 for each type of slope. Half of the plots had a size of 5.50 by 1.87 and other half had a size of 11.05 by 1.87 metres.The average annual rainfall was 1194.80 mm, overall runoff ratio averaging over slope shapes was 23.27 % and overall mean annual soil loss averaging over slope shapes was 2399.95 g m2.The average annual runoff and average annual soil loss were 291.04 mm and 3903.12 g m-2 for uniform runoff plots, respectively. The average runoff were 272.47 mm and 270.79 mm and average annual soil loss values were 1325.61 g m-2 and 1971.13 g m-2 on concave and convex runoff plots respectively. Slope shapes affect the amount of runoff and soil loss. The highest runoff and soil loss occurred from uniform plots. The lowest runoff was from convex slopes and the lowest soil loss occurred from concave slopes. The size of the plot did not have a significant effect on the soil loss from the plots with the same slope. In concave and convex slope shapes, the change in the length of the slope did not affect the amount of runoff in per unit area. Smaller plot size caused greater runoff in uniform slopes. On the other hand, plot level sticks were used to determine changes on the soil surface due to soil loss and deposition.