植被对风沙土风蚀作用的影响

以植物模型、风沙土为实验材料，以风洞模拟实验为研究手段得出初步结论：地表粗糙度为植被特征参数的函数，随植被盖度的增加呈幂函数增加；随植被作用区面积蛎呈线性增加；与行状植物的排列方向和主风向夹角的平方根成正比。在盖度相同的条件下，均匀分布较丛状分布可产生较大的粗糙度。风蚀率随植被盖度的减少呈指数增加。植被盖度对风沙土风蚀作用的影响可划分为３种程度类型：大于６０％为轻度风蚀和无风蚀。６０％￣２０％为中

INFLUENCES OF VEGETATION COVER ON THE WIND EROSION OF SANDY SOIL

Using plant models and typical sand soil as experiment materials, the influences of vegetation cover on soil erosion by wind were studied in wind tunnel. It was concluded that due to the interferences of vegetation, the boundary layer is divided into 2 sublayers approximately at the vegetation height. The upper is inertial sublayer in which the vertical wind gradient changes principle with vegetation characteristics, while length of the ground surface acts as the function of vegetation characteristic parameters.It increases with ground surface and acts as the function of vegetation characteristic parameters. It increases by power function with an increase in vegetation coverage linearly.It is proportional to the square root of the angle between vegetation alienation and wind direction. Given the same coverage,the evenly distributed vegetation is more effective than the unevenly distributed ones in wind erosion control. Erosion rate increases exponentially with vegetation coverage reduction.According to its influences on wind erosion intensity, vegetation coverage falls into 3 intensity categories:> 60% is nonerodible to slightly erodible; 60% 20% is moderately erodible;<20% is severely erodible. The above coverage index can be the references for those who carry out wind erosion control practices. In addition,in the course of vegetation change, air flow characteristics, roughness length and wind erosion mode are closely inter-related.