植被影响下坡面流阻力变化特征研究

Experimental study of overland flow resistance of different vegetation covers

坡面流阻力是反映坡面流水力学特性的重要特征值。利用人工模拟降雨试验,定量研究了在45、87和127mm/h降雨强度下,20°陡坡面裸地、草地和灌木地的坡面流阻力变化特征。结果表明,由于植被覆盖措施的阻滞作用,相对于裸地坡面,草地和灌木地坡面径流阻力系数明显增大。草地和灌木坡面阻力系数分别是裸地坡面的5.58～7.45倍和5.61～6.26倍。不同被覆条件下坡面平均阻力系数与降雨强度关系密切,随降雨强度的增大呈减小趋势。同时,坡面流阻力系数受到降雨强度和下垫面条件发育形态的共同影响。建立了不同被覆坡面的复合非线性阻力系数计算公式,变量系数表明草被覆盖度和降雨强度对坡面流阻力大小有着决定性的影响。该研究对于揭示植被调控坡面产流产沙机理,为生态修复工程建设提供科学依据具有一定的科学意义。

The overland flow resistance is an important hydraulic parameter. The overland flow resistances on bare slope, grass slope and shrub slope were studied on a 20° slope using simulated rainfall experiment. The results show that the runoff resistances of grass slope and shrub slope were significantly greater than that of bare slope due to the delaying role of vegetation cover. The runoff resistances was closely related to rainfall in- tensity and showed a decreasing trend with the increase of rainfall intensity. The runoff resistances of grass slope and of shrub slope were 5.58 -7.45 times and 5.61 -6.26 times that of bare slope, respectively. The nonlinear calculation equation of runoff resistance of different vegetation-covered slopes is built. The variation coefficient reflecting the vegetation cover and rainfall intensity play an important role on the overland flow re- sistance. The objective of this study is essential to understand the mechanism of vegetation influence on runoff and sediment yield and can provide scientific data for ecological restoration project construction.