放水冲刷条件下坡面植被空间布局对坡沟系统侵蚀产沙的影响研究

植被在有效防治水土流失、改善生态环境中具有不可替代的重要作用。研究表明,土壤表面没有植被的降雨侵蚀量是未扰动森林土壤的16倍1]。Zheng在子午岭林区的研究也发现,当地表植被生长良好时,降雨、地形、坡度等因素对土壤侵蚀量的影响很小。而土壤表层一旦失去植被保护或根系的固结时,降雨和地形等因素对侵蚀的作用则十分

Effect of downslope vegetation distribution on sediment yield of slope-gully system exposed to runoff scouring

Variation of vegetation distribution has very important effects on sediment yield on slope-gully system because of the erosion spatial variability. Taken the slope-gully system as the research object, which is composed of the 4 meters long slope and the 3 meters long gully slope, a series of simulated scouring experiments under the different flow discharges (3.2 L min-1, 5.2 L min-1) were conducted. The effects of the different flow discharges, different vegetation distribution along the slope (up-slope, middle-slope and down-slope) and different vegetation coverage degree (0, 30%, 50%, 70%, 90%) to the sediment yielding of slope-gully system were studied in this paper. The results show that whether the slope or the slope-gully system, the total runoff volume and the process of runoff yield have no obviously different among the three different grass disposal on slope under the same grass coverage and the same flow discharge, but the sediment yield has distinct discrepancy among the three different grass disposal on slope. That is, the different grass disposal on slope decreases the sediment yield not by reducing the runoff volume. The runoff yield 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 increase with the flow discharges raise under the same grass coverage, the same grass disposal on slope and the different flow discharges. The amount of sediment yield on gully section was not shows the tendency of decreasing with the flow discharge raising, but shows that increase with the flow discharge raising. According to this result, if we only take the measure of harnessing the slope and no harnessing the gully, the amount of sediment of gully section will increase with the raising of flow discharge s. So we should give attention to slope and gully when we harnessing the soil and water loss in watershed of Loess Plateau.