Regulation of vegetation pattern on the hydrodynamic processes of erosion on hillslope in Loess Plateau, China
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Abstract: As vegetation are closely related to soil erosion, hydrodynamic parameter changes under various vegetation pattern conditions can be used as an important basis for the research of the soil erosion mechanism. Through upstream water inflow experiments conducted on a loess hillslope, how the vegetation pattern influences the hydrodynamic processes of sediment transport was analyzed. The results show that the placement of a grass strip on the lower upslope can effectively reduce runoff erosion by 69%, relying on the efficiency of regulated hydrodynamic process. The effective location of grass strip for hillslope alleviating erosion is on the lower part of the upslope, mainly due to the grass strip measure used to regulate the hydrodynamic system. As a result, the underlying surface runoff resistance is increased by 5 times, runoff shear stress is decreased by more than 90%, and runoff power decreased by over 92%. The measure greatly separates the scouring energy of surface runoff that acts on the slope soil. Therefore, the use of grass strips effectively decreases the energy of runoff flowing along the slope, eliminating soil erosion to a great extent and thereby achieving a better regulation of hydrodynamic processe.
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Key words:
- Soil erosion /
- Grass strip /
- Scouring experiment /
- Sediment transport /
- Regulating mechanism /
- Loess Plateau
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Table 1. Design of the tested scouring–vegetation patterns
Vegetation pattern Scouring discharge (L/min) Position relative to slope top Vegetation coverage (%) Scouring duration (min) A 16 Bare slope 0 30 B 16 7–8 25 30 C 16 6–7 25 30 D 16 5–6 25 30 E 16 4–5 25 30 F 16 3–4 25 30 Table 2. Reduction in runoff shear stress at different cross-sections for different vegetation patterns (%)
Wetted cross section Vegetation pattern B C D E F 9-9 87.4 29.8 36.4 62.5 87.1 13-13 85.7 79.5 43.5 81.2 85.9 Table 3. Reduction in runoff shear stress at different moments for different vegetation patterns (%)
Time (min) Vegetation pattern B C D E F 15 89.3 77.9 72.6 80.3 93.0 25 87.1 75.2 59.2 79.4 91.0 Table 4. Decrease in runoff power at different cross-sections for different vegetation patterns (%)
Wetted cross section Vegetation pattern B C D E F 9–9 89.4 49.8 52.4 60.7 89.0 13–13 89.9 83.2 44.5 81.8 84.5 Table 5. Decrease in runoff power at different moments for different vegetation patterns (%)
Time (min) Vegetation pattern B C D E F 15 91.7 82.0 70.1 79.9 92.2 25 90.2 81.7 62.9 78.6 92.2 -
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