Effect of Unit Weight and Slope on Erosion

Laboratory tests were performed on a fine grained soil to determine the effect of unit weight and slope on erosion and runoff. The tests were conducted on slopes of 1:1, 2:1 and 3:1 using unit weights of 80, 85, 90 and 95 lb per cu ft and a simulated rainfall intensity of 6 in. per hr. After collecting the runoff water and solid particles, the weight of solids eroded and the volume of runoff water were determined. The results and analyses of this study indicate that the slope and unit weight have definite effects on the erosion of unprotected slopes. These indications are: (1) On the flattest slope, the specimens compacted to the lowest unit weight experience the highest rate of erosion; (2) on the steepest slope, the specimens compacted to the highest unit weight experience the highest rate of erosion; and (3) for a given unit weight, there is a unique slope from which the maximum amount of erosion will occur.