毛乌素沙地不同下垫面的风沙运动特征  

Aeolian Movement Characteristics over Different Underlying Surfaces in Mu Us Sandy Land

作　　者：吴晓旭[1,2] 邹学勇[1] 王仁德[1,3] 赵婧妍[1] 程宏[1] 钱江[1] 

机构地区：[1]北京师范大学地表过程与资源生态国家重点实验室/防沙治沙教育部工程研究中心,北京100875 [2]北京师范大学全球变化与地球系统科学研究院,北京100875 [3]河北省科学院地理科学研究所,河北石家庄050011

出　　处：《中国沙漠》2011年第4期828-835,共8页Journal of Desert Research

基　　金：国家自然科学基金项目(40971011;10532030)资助

摘　　要：基于野外实地观测,研究了毛乌素沙地不同下垫面的风沙运动特征。平坦流沙地上的风速随高度呈对数分布;沙丘上的风速梯度在高度上的变化随植被盖度增大而增强;相近风速下,0～60cm高度范围内的输沙强度从大到小依次为流动沙丘丘顶>平坦流沙地>半流动沙丘丘顶>裸露黄土梁地>黄土梁翻耕地>玉米留茬地>半固定沙丘丘顶。同一植被盖度下,沙丘顶部输沙率随风速增加而增大,粗糙度随风速增加而减小。当风速小于起沙风速时,粗糙度随植被盖度的增加而增大;当风速大于起沙风速时,平坦流沙地和沙丘顶部的粗糙度随风速增大有增加趋势,产生这种现象的可能原因是跃移层沙物质对气流的阻力随风速增大而增大。根据各类沙源地的起沙强度和总面积,风沙灾害防治的重点是植被盖度较小的沙地和黄土梁地。Aeolian movement characteristics over different underlying surfaces in Mu Us Sandy Land was researched based on field measurement.The results showed that wind profile over flat drifting sand followed logarithmical rule against height.Under similar wind-speed,the sediment discharge intensity within 0~60 cm successively distributed as mobile dune topflat drifting sandsemi-mobile dune topbare loess flat-topped ridgedumped loess cropland landmaize stubble landsemi-mobile dune top.At given vegetation coverage,sand transport rate over dune top increased as wind-speed increased,roughness decreased as wind-speed increased.When wind speed was below the threshold sand-blowing wind speed,roughness increased as vegetation coverage increased;When wind speed was above the threshold,roughness over flat drifting land and dune top showed a increasing trend with wind speed.This may result from increasing sand＇s saltation resistance to airflow when wind speed increased.Judging from sand-blown density and total area of underlying surface,key areas of sand disaster prevention lie in sandy land and loess flat-topped ridge with low vegetation coverage.

关 键 词：风速廓线 风沙流结构 输沙率 粗糙度 毛乌素沙地 

分 类 号：X169[环境科学与工程—环境科学]