XIAO Peiqing, YAO Wenyi, WANG Guoqing, YANG Chunxia, SHEN Zhenzhou. Effects of soil shear strength and runoff erosivity on slopes with different vegetation cover[J]. Advances in Water Science, 2016, 27(2): 224-230. DOI: 10.14042/j.cnki.32.1309.2016.02.007
Citation: XIAO Peiqing, YAO Wenyi, WANG Guoqing, YANG Chunxia, SHEN Zhenzhou. Effects of soil shear strength and runoff erosivity on slopes with different vegetation cover[J]. Advances in Water Science, 2016, 27(2): 224-230. DOI: 10.14042/j.cnki.32.1309.2016.02.007

Effects of soil shear strength and runoff erosivity on slopes with different vegetation cover

  • The combined effects of soil shear strength and runoff erosivity is important to quantitatively express the relationship between soil erosion resistance ability, runoff detachment, and transport capacity. We used field data and simulated rainfall experiments to study the effects of grass and shrub cover on runoff and sediment yield and its mechanical mechanism. Based on standard field plots data, runoff reduction on grass and shrub plots decreased by 28.1%-56.5% and 85.7%-100%, respectively, and sediment reduction on grass and shrub slopes decreased by 84.9%-90.7% and 98.5%-100%, respectively, compared with the bare plot. Under simulated rainfall intensities of 45, 87 mm/h and 127 mm/h on a 20° slope gradient, runoff reduction on grass and shrub slopes decreased by 51.9%-90.9% and 61.7%-80.6%, respectively, and sediment reduction on grass and shrub slopes decreased by 93.6%-99.2% and 95.5%-99.2%, respectively, compared with the bare slope. Vegetation can enhance soil shear strength. Soil shear strength was proportional to the vertical pressure on the shear surface, and it was consistent with Coulomb's law of shear strength. Soil cohesive force was negatively correlated with runoff as well as sediment yield. Runoff and sediment yield decreased with the increase in soil cohesive force. Sediment yield increased with the increase of flow shear stress, and there was a significant linear relationship between the two. The critical flow shear stresses of the grass slope and the shrub slope, respectively, were 2.64-3.16 times and 2.44-3.18 times that of the bare slope. The sediment transportation rate had a linear relationship with the flow shear stress. The critical flow shear stress and soil shear strength and the critical flow shear stress and soil cohesive force were significantly correlated. These relationships illustrate the mechanical effects of the soil erosion process. The results are useful for quantifying runoff and sediment reduction and understanding the mechanical process of soil erosion.
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