Abstract
Soil erosion is a major problem in the Loess Plateau (China); however, it can be alleviated through vegetation restoration. In this study, the overland flow on a slope during soil erosion was experimentally simulated using artificial grass as vegetation cover. Nine degrees of vegetation coverage and seven flow rates were tested in combinations along a 12° slope gradient. As the coverage degree increased, the water depth of the overland flow increased, but the flow velocity decreased. The resistance coefficient increased with increasing degree of coverage, especially after a certain point. The resistance coefficient and the Reynolds number had an inverse relationship. When the Reynolds number was relatively small, the resistance coefficient decreased faster; however, when it exceeded 600, the resistance coefficient decreased at a slower rate. A critical degree of vegetation cover was observed in the relationship between the resistance coefficient and submergence degree. When the degree of coverage was greater than 66.42%, the resistance coefficient first decreased and then increased with a higher submergence degree. Finally, the formula for the resistance coefficient under vegetation coverage was derived. This formula has a relatively high accuracy and can serve as a reference for predicting soil erosion.
Highlights
It can be observed from the table that overland flow water depth is affected by variation in the unit discharge and the degree of vegetation coverage
The flow velocity is between 0.168 and 0.447 m/s; when the degree of coverage is 9.76%, the flow velocity decreases to 0.158–0.395 m/s; and when the degree of coverage increases to 95.01%, the flow velocity can drop to 0.105–0.206 m/s
The experimental method developed in this study can accurately control the coverage of simulated vegetation and the rate of flow, which cannot be achieved in many natural conditions
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The Loess Plateau in China is situated in the arid continental monsoon climate zone; it experiences concentrated rainstorms and has a loose soil structure. It is an area that suffers from serious soil erosion as well as soil and water loss [1]. Improvements in vegetation coverage in recent years have helped ameliorate erosion losses to a certain extent [2]. In 1999, the vegetation coverage of the Loess Plateau was 32%, but it has since increased to 59%. The vegetation coverage in northern Shaanxi, which suffers from severe soil erosion, has increased significantly.
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