Workshop Activities on the Soil Erosion - MyAssignmenthelp.com

Question: 1. How effective has the 10% contact cover been in reducing soil erosion by rainfall? 2. On what slope the cover was most effective in reducing rainfall erosion? 3. What was the effect of slope on sediment concentration and soil loss? 4. Discuss the interaction between slope and surface contact cover on soil loss and sediment concentration. Answer: Answer 1 Erosion is enhanced by the speed of the moving water and by reducing the amount of exposed surface, there is a reduction in the number of sediments transported downslope. Majorly, erosion is of four types which are as a result of direct rainfall: sheet, rill, splash and gully erosions. However, of the four processes, splash erosion is the initiator which is followed by sheet erosion while rill and gully follow it consecutively. It has been noted that the most severe of the erosion processes is the splash erosion which is caused by the raindrops falling on the bare surface. The raindrops have the kinetic energy to dislodge the soil particles from the matrix and therefore initiate the erosion process. Therefore a reduction in the amount of surface exposed to the rain results to a decrease in the amount of erosion. The experiment indicates that erosion for the slopes with gradients of 2%, 4%, 6%, 8% and 10% is higher on surfaces without cover than on the same surfaces with cover. However, the same is not true for the surfaces with slopes of 1%, 3%, 5%, 7% and 9%.The discrepancy has been rectified by the line of best fit.However,comparison may be observed on a bar graph. Answer 2 Slope gradient, as well as the amount of cover provided, determine the number of sediments transported by runoff. Therefore, it can be said that a 0% gradient does not result into any runoff because the rainwater does not have enough energy to transport the soil downslope. An increase in gradient is likely to lead to an increase in the amount of erosion and as it has been demonstrated from the experiment, a 10% cover on the 2% gradient has the most predominant cover to erosion. The 2% gradient has prevented soil loss by approximately 46.66 % compared to the other slopes which have slightly lower effects on the soil loss. Answer 3 According to the data obtained from the experiments, the slopes do have a profound effect on the soil loss as well as the sediment concentration. However, it is important to note the type of surfaces used in the experiment. In determining the sediment concentration, there is a comparison on slopes with the strip and those with no strips. On the other hand, analyzing soil loss involves surfaces with cover and those with no cover. Increase in slope has the effect of increasing the sediment concentration on the no strip slopes. This can be observed from the 3% gradient all the way to the 10% gradient. In this regard, the 10% gradient has the maximum sediment concentration with 30.365g/l. As with the strip slope, the sediment concentration increases all the way to the 8% gradient but reduces the 9% before increasing. As with the no cover surfaces, there is an increase in soil loss with the 8% gradient having the maximum soil loss with a loss of 918.032g/m2/ hour. As with the surfaces with cover, the amount of soil loss increases from the 2% gradient with the maximum soil loss observed in the 7% gradient (1765.416 g/m2/hour).Therefore, an increase in gradient results to an increase in the sediment concentration as well as the soil loss. Answer 4 There are primarily two factors that determine the amount of erosion on any surface: the amount of vegetation/cover and the gradient of the slope. The gradient is proportional to the erosion while the surface cover is inversely proportional to the erosion. As it can be observed from the experiment, surfaces with cover and those with no cover have different rates of soil loss. In this regard, those with cover have a reduced rate of erosion compared to those with no cover.