%0 Journal Article %A Hewei SHENG %A Liying SUN %A Qiangguo CAI %T Steady sediment concentration of sheet erosion on loess slope and influencing factors %D 2016 %R 10.18306/dlkxjz.2016.08.010 %J PROGRESS IN GEOGRAPHY %P 1008-1016 %V 35 %N 8 %X

Soil erosion on the loess hillslope shows clear vertical zonal differentiation. From upslope to downslope locations, the erosion zones are sheet erosion zone, rill erosion zone, and shallow gully erosion zone. Sediment concentration of sheet erosion zone has important impacts on detachment, deposition, and transportation processes of rill erosion zone. The purpose of this study was to investigate the relationship between steady sediment concentration and different influencing factors including loess soil type, rainfall intensity, and slope gradient. The relationship between steady sediment concentration and shear stress, stream power, and unit stream power were also examined. The impacts of loess soil type, rainfall intensity, and slope gradient on sediment concentration in rain-induced sheet flow were examined by artificial rainfall experiment from June to August 2015. Two loess soils from Yangling and Changwu districts were subjected to simulated rainfall using a detachment tray under infiltration condition. Two rainfall intensities of 90 and 120 mm/h were simulated on slope gradients from 10° to 25°, resulting in rain-induced overland flow. The sediment was sampled at several time intervals and sediment concentration was determined. Different hydraulic parameters including flow velocity, shear stress, stream power, and unit stream power were measured. The results show that: (1) Sediment concentration demonstrated a similar trend under different conditions: first sharply decreased and then became steady. A new equation can be used to model changes of sediment concentration, with the minimum value of the equation as steady sediment concentration. Sediment concentration was greater at higher rainfall intensity and steeper slope gradients. With slope gradient increasing from 10°to 25°, sediment concentration increased from 4.3 to 6.25 kg/m3 and 9.56 to 18.53 kg/m3 at rainfall intensities of 90 and 120 mm/h on Lou soil hillslope; and increased from 4.76 to 12.42 kg/m3 and 9.72 to 19.08 kg/m3 at rainfall intensities of 90 and 120 mm/h on Dark loessil soil hillslope, respectively. The steady sediment concentration was lower with higher fractal dimension of loess particles. The impacts of factors on steady sediment concentration are in the following order: fractal dimension of loess particles > rainfall intensity > slope gradient; (2) Unit stream power was the hydrodynamic parameter that was most closely correlated with steady sediment concentration, and a new model including rainfall intensity, unit stream power, and fractal dimension of loess particles was advanced to calculate steady sediment concentration. The impacts of factors on steady sediment concentration are in the following order: fractal dimension of loess particles > rainfall intensity > unit stream power.

%U https://www.progressingeography.com/EN/10.18306/dlkxjz.2016.08.010