坡面薄层水流分离土壤的动力学机理

Dynamic Mechanism of Soil Detachment by Shallow Flow on Slope

为探讨土壤分离过程的水动力机理及植被根系对土壤分离的抑制作用,采用变坡实验水槽,系统研究坡度、流量及根系对土壤分离速率的定量影响。结果表明,土壤分离速率是坡度、流量及根系密度的函数;植被根系能显著降低土壤分离速率,草地土壤分离速率均值仅为休闲对照地的30.6%;随根系密度增加,土壤分离速率呈指数关系下降;0～4 kg/m3为根系减少土壤分离的有效密度区间,在此范围内,根系密度的增加能引起土壤分离速率的急剧降低,超过4 kg/m3,随根系密度增加,土壤分离速率的降幅并不明显。

This study was conducted to investigate the hydro-dynamic mechanism of soil detachment and the erosion-reducing effects of grass root.Soil detachment rate was measured using a laboratory flume to study the relationships between it and slope gradient,flow discharge,and grass root.The experimental results indicated that soil detachment rate could be predicted accurately using slope gradient,flow discharge,and root density.The mean value of root-permeated soil detachment rate（switch grass） accounted for 30.6% of bare soil＇s since root could abate soil erosion evidently.Soil detachment rate declined following an exponential law against increasing root densities.The remarkable decline in soil detachment rate mostly occurred in the root densities range 0-4 kg/m^3 for its sensitivity to soil resistance,and grass root densities 4 kg/m^3 did not contribute significantly to additional soil resistance.