植株减小风速从而抑制风蚀,风速廓线可以反映植株对风速的影响。在风洞中测量了细长状植株和上大下小形状植株在不同覆盖密度、不同来流风速下的风速廓线,并对这两种植株地表上空气动力学粗糙度、零平面位移高度进行了比较。结果表明:两种植株地表的空气动力学粗糙度均随植株密度按幂函数规律增加,其与植株高度之比也随侧影盖度按幂函数规律增加。在相同覆盖密度或侧影盖度条件下,上大下小形状植株地表的空气动力学粗糙度大于细长状植株。细长状植株地表的零平面位移高度随植株密度的增加先增加而后减小,而上大下小形状植株地表的零平面位移高度则基本不受植株密度的影响。
Plants reduce wind speed resulting in the lower soil wind erosion. The characteristics of wind velocity profile are a reflection of wind speed variation at the surface of different plants. In this paper, the wind velocity profiles above two plant surfaces (the first is the slender plants and the second is the plants with large upper part and small lower part) are measured at different plant density and free-stream wind speed in a wind tunnel, then the aerodynamic roughness length and zero-plane displacement are analyzed. The results show that the aerodynamic roughness length of the two plant surfaces increases with plant density according to the power function, and its ratio to plant height also increases with lateral cover by the power law. At the same plant density or lateral cover, the aerodynamic roughness length of the second plant surface is larger than that of the first one. The zero-plane displacement of the first plant surface increases first and then decreases with the increase of plant density, while the zero-plane displacement of the second plant surface is generally unaffected by plant density.
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