黑麦草密度对坡面水流阻力影响的试验研究

The Effects of Ryegrass Density on Hydraulic Resistance of Slope Against Overland Water Flow

【目的】提高生态工程的水土保持效益,合理利用坡面植被挡蓄径流,减轻坡面工程土壤侵蚀。【方法】通过室内试验,模拟水流在不同密度植被覆盖下的坡面流动时水深及阻力的变化规律,详细描述坡面沿程水深规律并建立水深方程,研究阻力在整个坡面的分布及变化过程。【结果】①由坡面水深方程推求得出了水流所受坡面总阻力方程。②刚性植被与柔性植被在坡面阻流中对水流的阻碍作用不同,植被对坡面水流的阻力不随植被密度增大而增大,坡面植被存在最优种植密度,使阻水效果最佳。【结论】在治理低山丘陵区的水力侵蚀时,植被种植密度不宜过疏或过密,坡面植被存在最优种植密度,使阻水效果最佳。

【Background】Reconstructing engineering projects to restore ecosystems functions has been in increase over the past few years,one issue in which is to restore vegetation coverage of slopes to reduce water and soil erosion.【Objective】The purpose of this paper is to experimentally study if and to what extent increasing planting density of ryegrass can improve hydraulic resistance of slopes against overland water flow and improve water infiltration.【Method】The experiment was conducted in laboratory.We measured and calculated the changes in water depth and hydraulic resistance of water flow over the slopes under different vegetation coverages.【Result】①Equations were derived to describe the spatiotemporal changes in water depth and total hydraulic resistance of water flow over the slopes.②Rigid vegetation and flexible vegetation affected water flow in the slopes in different ways.The hydraulic resistance of the vegetation to water flow over the slope did not increase with the planting density monotonically;there was an optimal density which was most effective for the vegetation to hoard the water and slow down water flow.【Conclusion】Care should be taken in using vegetation to mitigate water and soil erosion from slopes in low mountainous and hilly areas.There was an optimal vegetation density which is most effective to slow waterflow over the slopes while in the meantime improve water infiltration.