塔里木沙漠公路对近地表风沙运动过程的影响

通过对塔克拉玛干沙漠腹地野外试验数据的分析,探讨了塔里木沙漠公路对近地表风沙运动过程的影响.结果表明:①阻沙栅栏和草方格固沙带对近地表气流的速度和风速廓线形成很大影响,风速整体被削弱,而且越接近地表,削弱程度越大,风速廓线的垂直梯度增加;②在防沙体系内,地表输沙率急剧下降,风沙流结构发生很大变化,下层含沙量下降,而上层含沙量相对变化较少,在阻沙栅栏的积沙带和草方格固沙带内上层含沙量趋于均匀分布;(3) 阻沙栅栏和草方格固沙带也影响沙丘的移动.当主导输沙风向与栅栏相交呈小角度时,靠近栅栏的沙丘顺栅栏走向侧向移动相交呈大角度时,移动方向变化不大,草方格固沙带不影响沙丘的移动方向;阻沙栅栏和草方格固沙带能降低沙丘的移动速度,而在固沙带内部,由于沙丘的逆向演变,沙丘体积减小,移动速度较快.

Study on the Effects of the Tarim Desert Highway on the Process of Blown Sand Movement near the Ground Surface

This paper discusses the effects of the Tarim Desert Highway crossing the Taklimakan Desert on the blown sand movement near the ground surface based on the data derived from the field experiment and survey at the west Tazhong region in the hinterland of the Taklimakan Desert.The results are as follows:(1) Wind velocity is decreased because of the influence of upright fence and reed checkerboard barriers upon air flow and wind profile near the ground surface,and the vertical gradient of wind velocity is increased.The closer the anemoscope to the ground surface is,the more significant the decreased wind speed will be;(2) The sand transport rate near the ground surface in shelter systems is sharply decreased,and the flux profile of blown sand near the ground surface is significantly changed,that is the sand content is decreased in lower air but relatively increased in upper air,however,it is evenly distributed in the sand sediment zone of the upright fences and the sand-fixing zone of the reed checkerboards;(3) Dune movement can be restricted by fences and reed checkerboards.When the angle between the direction of prevailing wind and the fences is small,the dunes windward from the fences move laterally along the fences,but when the angle between the direction of prevailing wind and the fences is large,the change of dune moving direction is not so significant;the dune moving direction is not affected by reed checkerboards;dune movement can be reduced by fences and reed checkerboards,but the dunes in the reed checkerboards move faster due to the inverse evolvement.