Experimental study on the effect of slope vegetation distribution variation on runoff and sediment yield in slope-gully system
不同坡面植被空间布局对坡沟系统产流产沙影响的实验

The runoff erosion formation and the sediment yield intensity present a vertical distribution because of the complicated topography and the special climate condition in the Loess Plateau of China. The variation of vegetation distribution has great effects on sediment yield in slope-gully system because of the erosion spatial variability. The authors, taking the slope-gully system as a research object, which is composed of the 4-meter-long slope and the 3-meter long gully slope, made a series of simulated scouring experiments under different flow discharges (3.2 L/min, 5.2 L/min). This paper studies the effects of different flow discharges, different vegetation distribution along the slope (up-slope, middle-slope and down-slope) and different vegetation coverages (0, 30%, 50%, 70%, and 90%) to the sediment yielding of slope-gully system. The results show that, the total runoff volume and the process of runoff yield have no obvious difference among the three types of different transplanted grass on slope under the same grass coverages and the same flow discharges, but the sediment yield has distinct variation among the three types. That is, different types of grass decrease the sediment yield not by reducing the runoff volume. The total runoff discharge is only related to the grass coverage on slope and the flow discharge under the experimental condition. The amount of sediment yield on gully section increases with the increase of the flow discharges under the same grass coverage, as well as the same transplanted grass on slope. The amount of sediment yield on gully section did not show a decreasing tendency when the flow discharge is raised, but showed an increasing tendency instead. According to this result, if we only take the measure of harnessing the slope without harnessing the gully, the amount of sediment of gully section will increase with the rise of flow discharges. So we should give attention to slope and gully when we harness the soil and water loss in watersheds of the Loess Plateau.