植被盖度对沙丘风沙流结构及风蚀量的影响

以科尔沁沙地不同植被盖度沙丘为研究对象，采用野外可移动风洞进行原位测试，开展了沙丘植被盖度对风沙流输沙率影响的研究，探讨了地表风蚀量与风速及植被盖度的关系。结果表明：空气动力学粗糙度随植被盖度增加先平缓后剧烈，与植被盖度相关关系呈三次函数增长。在各植被盖度下各层输沙率均随高度增加而递减，随风速增加而递增。同一植被盖度下风蚀量随风速增加而增大，符合幂函数或二次函数关系，但二次函数相关性更高。同一风速下风蚀量随植被盖度的增加呈阶梯式降低，在盖度小于27%时风蚀量平缓下降，盖度27%~43%时风蚀量急剧下降，盖度43%以上时风蚀量下降重新趋于平缓。相对截留率随风速增大而减小，随植被盖度增加而增大，沙丘草本植被盖度43%以上时具有较好的防风固沙效果，此时平均截留率达88.02%。

Influence of Vegetation Coverage on Sand Flow Structure and Wind Erosion Yield with Wind Tunnel Experiment as a Case

Based on the sandy dunes with different vegetation cover in Horqin Sandy Land, the in-situ test was carried out by the movable wind tunnel in the field. In order to explore the quantitative relationship between the surface wind erosion yield and the wind speed and vegetation coverage, the effects of vegetation coverage on the sediment transport rate of sand flow were studied. The results showed that aerodynamic roughness changed with the increase of vegetation coverage, with firstly gentle and then steep trend, the correlation of them showed a cubic function growth; The sediment transport rate of each layer decreased with increasing height for each vegetation coverage, and increased with increasing wind speed; The wind erosion yield increased with increasing wind speed at the same vegetation coverage, and the correlation can be described by power function or quadratic function. Moreover, the quadratic function correlation was superior to the power function; At the same wind speed, the amount of wind erosion decreases stepwise with the increase of vegetation coverage, the wind erosion yield decreased gently with vegetation coverage less than 27%, when the coverage ranged from 27% to 43%, the wind erosion yield decreased sharply, and the wind erosion yield decreased slowly and tended to be stable when the coverage was over 43%; The relative interception rate decreased with the increase of wind speed, and increased with the increase of vegetation coverage. It would exhibit good wind and sand fixation effects when the coverage of the dune herbs more than 43%, the average relative interception rate reached 88.02%.