坡面草被覆盖对坡沟侵蚀产沙过程的影响

Impact of Different Grass Coverages on the Sediment Yield Process in the Slope-gully System

通过室内放水冲刷试验方法,研究了坡沟系统坡面不同草被覆盖度及空间配置下,坡沟系统侵蚀产沙变化过程及特征。结果表明,放水流量较小时,覆盖度越高,侵蚀产沙量越小;坡面草被不同空间配置下的产沙量大小依次是:坡上部>坡中部>坡下部。大流量时,不同草被覆盖度间的产沙量差异增大,不同草被空间配置下的产沙量变化规律不十分显著。沟坡产沙比随坡面草被覆盖度的增加呈指数增加,大流量比小流量下的增加幅度要大。坡面草被布设在坡下部时,其对沟坡侵蚀的危害最大。坡沟系统侵蚀产沙变化过程是增加—稳定—下降,其变化的阶段性不如单一坡面明显。

By scouring experiments, the changeable process and characteristics of sediment yield in the slope-gully system with different coverages and spatial location of grass were studied. Results showed that the sediment yield decreased with increasing grass coverage at smaller water inflow rates in scouring experiments. The sediment yield with different grass locations on the sloping surface was in the order of upper 〉 middle 〉 lower. At larger water inflow rates, the differences of sediment yield among various grass coverage were enlarged, whereas the changeable tendency of sediment yield with different grass locations on the sloping surface was not very obvious. The proportion of sediment yield from the gully increased in an exponential relationship with increasing grass coverage, and the increasing degree for large water inflow rate is larger than that of the small one. When the grass was located on the lower position on sloping surface, the influence for accelerating gully erosion is the largest. The changeable process of sediment yield in slope-gully system was to increase first and then to decrease.