不同覆盖度条件坡面水流阻力规律

Overland Flow Resistance Law Under Different Vegetation Coverage

为探明植被覆盖条件下坡面水流阻力特性,以流体力学和水力学基本理论为依据,通过6个坡度、7个流量和5种覆盖度组合条件下室内放水试验,系统研究了植被覆盖条件下坡面水流阻力的特征。结果表明:坡面植被水流曼宁系数随水深、雷诺数、坡度的变化与植被覆盖度密切相关,当植被覆盖度较高时,曼宁系数随水深、雷诺数的增加而增大,随坡度的增加而减小;相反,当覆盖度较低时,曼宁系数随水深、雷诺数的增大而减小,坡度对曼宁系数的影响逐渐减小;各试验工况下,曼宁系数随弗汝德数的增大呈单调递减趋势,增加最终都趋近于稳定值。

Based on the basic theory of fluid mechanics and hydraulics,the resistance characteristics of overland flow were systematically investigated under 6slope gradients,7flow discharges and 5vegetation coverage degrees so as to explore the resistance characteristics of overland flow under different vegetation coverage.Results showed that the variances of Manning coefficient with flow depth,Reynolds number,and slope gradient were closely related to the vegetation coverage.As water depth and Reynolds number increased,the Manning coefficient increased under high vegetation coverage while showed a deceasing trend under low vegetation coverage.The influence of slope gradient on Manning coefficient gradually decreased with vegetation coverage degrees reducing.Under all test conditions,the Manning coefficient decreased with the increase of Froude number,but there was a limit of this trend.The study is of scientific significance in understanding the mechanisms of regulating slope runoff and sediment yields by vegetation.