Detachment characteristics of root-permeated soils from laboratory jet erosion tests
Detachment characteristics of root-permeated soils from laboratory jet erosion tests
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DOI：
10.1016/j.ecoleng.2016.10.081
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发表时间：
2017-03
影响因子：
3.8
通讯作者：
A. Khanal;G. Fox
中科院分区：
文献类型：
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作者：
A. Khanal;G. Fox
在不同的时空尺度上，植被对流沙动态的影响已经得到了充分的研究。植被可能是稳定河滩最有效的措施之一。传统上，关于植被根系对河岸稳定影响的研究主要集中在地表生物量的机械加固和减少施加的剪应力上。很少有研究研究根系对河流沉积物分离的影响。本研究在裸地土壤样品上进行了36次微喷流侵蚀试验（mini-JETs），在根系渗透土壤样品（平均根径0.5 ~ 1.7 mm）上进行了29次微喷流侵蚀试验（mini-JETs），以确定根系在抗侵蚀中的作用。研究还估计了线性超剪应力模型（可蚀性系数kd和临界剪应力τc）和非线性脱离模型Wilson模型（b0andb1）的参数，并研究了这两个模型参数与根系特性的相关性。根系渗透土在较高剪切应力下的抗侵蚀能力更强，植被土壤的τcandb1参数平均高于裸土。随着根径的增加，土壤样品在高剪应力下的侵蚀速率降低。线性和非线性脱离模型的可蚀性系数参数（b0和kd）通过幂函数与根径呈显著负相关。临界剪应力轨道1与根系参数之间无显著相关关系，支持前人的研究结论。超剪应力模型参数与非线性脱离模型参数之间存在显著相关；特别是植被样品的τcandb1之间的相关性较高。因此，根渗透土壤的侵蚀速率降低主要是通过增加剥离前所需的剪应力。
The influence of vegetation on flow and sediment dynamics at various spatial and temporal scales has been well documented. Vegetation may be one of the most effective measures in streambank stabilization. Traditionally, research on the influence of vegetation roots on streambank stabilization has focused on mechanical reinforcement and reduced applied shear stress due to above ground biomass. Few studies have investigated the effect of roots on fluvial detachment of sediment. This study conducted 36 mini-jet erosion tests (mini-JETs) on bare soil samples and 29 mini-JETs on root-permeated soil samples (average root diameters of 0.5 to 1.7 mm) to determine the role of roots in erosion resistance. The research also estimated parameters of the linear excess shear stress model (erodibility coefficient, kd, and critical shear stress,τc) and a nonlinear detachment model called the Wilson Model (b0andb1) and investigated the correlations between parameters of the two models and root characteristics. Root-permeated soil samples were more erosion resistant at higher shear stress as theτcandb1parameters were on average higher for the vegetated samples than the bare soil samples. As root diameter increased in the soil samples, erosion rates at high shear stress decreased. The erodibility coefficient parameters (b0and kd) of both the linear and nonlinear detachment models were negatively and significantly correlated to root diameter through power functions. No significant correlation was detected between critical shear stress orb1and root parameters which supports conclusions of previous studies. Significant correlations were observed among the parameters of the excess shear stress model and the nonlinear detachment model; especially high correlation was observed betweenτcandb1for the vegetated samples. In conclusion, root-permeated soils exhibited lower erosion rates primarily through increasing the required shear stress before detachment.