Land use impacts on soil detachment capacity by overland flow in the Loess Plateau, China

Land use and its adjustment may greatly affect soil detachment process by overland flow via altering soil properties, root systems, and tillage operations, but few studies were performed to quantify their effects on soil detachment in the Loess Plateau. This study was conducted to investigate the potential effects of land use on soil detachment capacity by overland flow (Dc, kgm−2s−1) using natural undisturbed soil samples taken from four different land uses on the red loess soil and six different land uses on the yellow loess soil, and to quantify the relationships between soil detachment capacity and hydraulic parameters, soil properties, and root systems in the Loess Plateau. The collected samples were tested in a 4.0m long, 0.35m wide hydraulic flume under six different shear stresses (5.51–16.59Pa). The result showed that both soil type and land use had significant effects on Dc. For two tested soils, the mean Dc of the yellow loess soil was 1.49 times greater than that of the red loess soil. For the red loess soil, Dc of cropland was the maximum, which was 5.57, 5.85, and 34.08 times greater than those of shrub land, orchard, and grassland, respectively. For the yellow loess soil, cropland was much more erodible than other five land uses. On average, the ratios of the cropland Dc to those of orchard, shrub land, woodland, grassland, and wasteland were 7.14, 12.29, 25.78, 28.45, and 46.43, respectively. The variability of Dc under different land uses was closely related to soil properties, root systems, and tillage operations. Soil detachment capacity was positively related to silt content, and inversely related to sand content, cohesion, water stable aggregate, aggregate median diameter, organic matter, and root density. The measured detachment capacity could be well estimated by measurable parameters of stream power, slope gradient, soil bulk density, median diameter, silt content, cohesion, and root density (Nash–Sutcliffe efficiency=0.89).