草被覆盖阻延坡面流作用试验研究

Experimental Study on Delay of Grass Coverage on Overland Flow

草被覆盖对坡面流有明显的阻延作用。本项研究旨在通过室内放水冲刷试验,揭示黄土丘陵区坡沟系统坡面不同草被覆盖对坡面流出流时间和终止时间的影响。试验分为坡沟系统试验及单一坡面试验2种,试验中坡面草被覆盖面积比分别为0,30%,50%,70%和90%,草被覆盖空间配置分为坡上部、坡中部和坡下部,放水冲刷流量为3.2 L/min和5.2 L/min。结果表明,坡面流出流时间与放水流量呈负相关关系,与草被覆盖面积比呈正相关关系;径流终止时间与放水流量和草被覆盖面积比均呈正相关关系;草被覆盖面积越大,其对坡面流的延滞作用越显著,放水流量越大,草被覆盖对坡面流的延滞作用越小。坡面草被布设在坡上部和坡中部时,其对坡面流的阻延作用相对较大。

Grass coverage has great influence on the stay of overland flow. The objective of this study is to reveal the influence of grass coverage on the time of runoff beginning and stop in the hillslope-gully slope erosion system on loess hilly area. In scouring experiments, five grass coverage degrees （0. 30%, 50%, 70% and 90%）, three spatial distributions of grass on the hillslope （upper, middle and lower） and two water inflow rates （3.2 L/min and 5.2 L/min） were used in the experimental soil box for the hillslope-gully slope erosion system experiment and the single hillslope experiment. Results showed that in the scouring experiments the time of runoff beginning has a negative relationship with the water inflow rate, and has a positive relationship with the grass coverage percentage. The time of runoff stop has a positive relationship with the water inflow rate and the grass coverage percentage. The delaying role of grass coverage on runoff increased with increasing grass coverage percentages and decreased with increasing water inflow rates. Usually, when the grass coverage was located on the upper and middle sections, the delaying role is relatively larger.