Temporal and spatial distribution characteristic of water-sand flow in vertical belts of soil erosi

Temporal and spatial distribution characteristics of erosion in the soil erosion chain of slopegully system are studied by experimental approach of artificially simulated rainfall, and the composite model with sections of different grades, which is representative of vertical belts of typical slopegully system on Loess Plateau, is adopted in the experiment. Results show: the process of sediment production is characteristic of peaks. When the rainfall density is 29.7mm/h, the erosion is primarily the surface erosion and there are three fluctuations in the process of sediment production. When the rainfall density is 60.5mm/h, the surface erosion and the rill erosion are the main erosion types, attended by gravity erosion, such as landslip and slippery collapse etc. When the rainfall density is 90.2mm/h, the rills develop fully, some rills begin to converge and shallow gullies appears on the down section of 25°, and severe landslip and slippery collapse occur on the slope section of 35°. The lower is the slope section, the greater is the runoff amount formed on it. The runoff yield per unit area and per unit time on various slope sections is arranged in the following order: the gully slope>the lower hill slope>the middle hill slope>the upper hill slope. Because of the runoff from upper slope, the sediment yield on the replatgirder slope increases by 20.2%～63.5% and that on the gully slope grows by 42.9%～74.5%. If the runoff from upper slope and the runoff yield can be controlled effectively, the sediment produced by erosion will be reduced substantially.