Representation of vegetation and other nonerodible elements in aeolian shear stress partitioning models for predicting transport threshold
Representation of vegetation and other nonerodible elements in aeolian shear stress partitioning models for predicting transport threshold
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DOI：
10.1029/2004jf000281
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发表时间：
2005-12-01
影响因子：
3.9
通讯作者：
Gillies, JA
中科院分区：
文献类型：
--
作者：
King, J;Nickling, WG;Gillies, JA
[1]非侵蚀性元素的存在被认为是土壤风蚀的一个减少因素，但其对地表的保护和侵蚀阈值预测的限制因元素的几何形状、空间组织和密度的变化而变得复杂。由于植被减少风蚀的有效性的代表性差，最新的模型估计风驱动的颗粒通量的预测能力降低。考虑到粗糙度对泥沙输移阈值的影响，采用了两种方法。Marticorena和Bergameetti（1995）在其粉尘排放模型中，假设粗糙度密度与表面的空气动力学粗糙度长度之间存在关系，从而将粗糙度对阈值的影响参数化。Raupach等人（1993）提出了一种不同的方法，该方法基于对单个粗糙度元素后面的尾流发展进行物理建模，并将粗糙表面上的表面应力和总应力分开。模型之间的比较表明，分区的方法是一个很好的框架来解释粗糙度的影响夹带泥沙风。这两个模型提供了非常好的协议，风洞实验中使用的固体物体上的nonerodibility表面。然而，当表面粗糙度长度和总粗糙度长度之间的差异太大时，Marticorena和Bergameetti（1995）的方法显示出缩放依赖性，而Raupach等人（1993）的模型预测效果更好，因为它包含了粗糙度几何形状及其可能引起的流动变化。
[1] The presence of nonerodible elements is well understood to be a reducing factor for soil erosion by wind, but the limits of its protection of the surface and erosion threshold prediction are complicated by the varying geometry, spatial organization, and density of the elements. The predictive capabilities of the most recent models for estimating wind driven particle fluxes are reduced because of the poor representation of the effectiveness of vegetation to reduce wind erosion. Two approaches have been taken to account for roughness effects on sediment transport thresholds. Marticorena and Bergametti ( 1995) in their dust emission model parameterize the effect of roughness on threshold with the assumption that there is a relationship between roughness density and the aerodynamic roughness length of a surface. Raupach et al. ( 1993) offer a different approach based on physical modeling of wake development behind individual roughness elements and the partition of the surface stress and the total stress over a roughened surface. A comparison between the models shows the partitioning approach to be a good framework to explain the effect of roughness on entrainment of sediment by wind. Both models provided very good agreement for wind tunnel experiments using solid objects on a nonerodible surface. However, the Marticorena and Bergametti ( 1995) approach displays a scaling dependency when the difference between the roughness length of the surface and the overall roughness length is too great, while the Raupach et al. ( 1993) model's predictions perform better owing to the incorporation of the roughness geometry and the alterations to the flow they can cause.