Experimental study on the sediment yield characteristics in slope-gully system

The slope-gully system is between slope scale and watershed scale. Revealing the sediment yield characteristics in the slope-gully system is very important to understand watershed erosion and sediment and build the sediment yield model of watershed. Taking the slope-gully system as the research object, which was composed of four meters long slope(20°) and three meters long gully slope(50°), a series of simulated scouring experiments under the different flow discharges(2.125, 3.205, 5.250, 7.185 L/min) were conducted. The results show that the spatial distribution of erosion from the up-slope to down-slope shows a tendency of decreasing at the top of slope and increasing at the middle part of slope and decreasing at the lower part of slope. The erosion of each section in the slop-gully system from the up-slope to down-slope is closely related to the flow discharges and the flow rates. The larger the flow discharges and the flow rates, the larger erosion of each section in the slope-gully system. The ratio of the sediment yield on gully section to the total sediment yield in the whole slope-gully system increases from 38.13%(at a flow discharge of 2.125 L/min) to 56.01%(at a flow discharge of 7.185 L/min) under the experimental condition. For the harness of the soil and water loss in Loess Plateau, only controlling the slope or gully will not reduce the sediment yield effectively. Comprehensive harness is the effective measure to reduce the sediment yield in Loess Plateau.