策勒绿洲-沙漠过渡带回涡沙丘形态动力特征  

Morphodynamic characteristics of echo dunes in the Cele oasis-desert transition belt

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作  者:马玉娇 毛东雷[1,2] 来风兵 李鑫鑫[1,2] 何强强 MA Yujiao;MAO Donglei;LAI Fengbing;LI Xinxin;HE Qiangqiang(College of Geographical Sciences and Tourism,Xinjiang Normal University,Urumqi 830054;Xinjiang Key Laboratory of Lake Environment and Resources in Arid Areas,Urumqi 830054)

机构地区:[1]新疆师范大学地理科学与旅游学院,乌鲁木齐830054 [2]新疆干旱区湖泊环境与资源重点实验室,乌鲁木齐830054

出  处:《干旱区资源与环境》2024年第9期157-164,共8页Journal of Arid Land Resources and Environment

基  金:国家自然科学基金地区项目(42061003)资助。

摘  要:策勒绿洲-沙漠过渡带灌丛沙堆上风向普遍发育回涡沙丘,采用数理统计方法对策勒绿洲-沙漠过渡带回涡沙丘形态指标及回涡沙丘各地貌部位的输沙量、风速和沙物质的粒度特征进行相关分析,有助于揭示风沙流与植被对沙丘形态与物质组成的作用方式。结果表明:1)发育成熟的回涡沙丘形如新月,灌丛和灌丛沙堆的形态特征影响回涡沙丘的形态特征。回涡沙丘宽度随灌丛沙堆宽度的增大而逐渐增大,在沙丘形成初期回涡沙丘高度随灌丛沙堆高度增加的不明显,后期回涡沙丘高度随灌丛沙堆高度增大而逐渐增大。2)回涡沙丘涡槽气流反卷,风速最小,侧翼气流发生绕流,风速最大。3)五个地貌部位侧翼输沙量最大,涡槽输沙量最小,各地貌部位距水平地面越近输沙量越大。五个地貌部位的风沙流结构特征值λ均大于1,各地貌部位主要以风蚀和搬运过程为主,灌丛疏透度变大或枯死,会导致回涡沙丘发生消散。4)回涡沙丘表面沙物质主要由极细砂、细砂、极粗粉砂组成,风速越大风沙流携沙粒径越粗,回涡沙丘侧翼风沙流携沙物质粒径最粗,灌丛沙堆背风坡风沙流携沙物质粒径最细。回涡沙丘表面沙物质平均粒径粗于灌丛沙堆。回涡沙丘与灌丛沙堆的形态特征影响不同地貌部位流场变化及沙物质粒度特征空间分异。In Cele oasis-desert transition zone,echo dunes generally develop from upwind of the nabkhas,so,the morphological indexes of echo dunes,the sediment runoff,wind speed,and particle size characteristics of geomorphic parts of echo dune were analyzed by mathematical statistics,it is helpful to reveal the effect of wind-drift sand and vegetation on the morphology and material composition of the dune.The results indicate that:1)The shape of a mature echo dune is crescent,and the morphological characteristics of scrub and nabkhas affect the morphological characteristics of the echo dune.The width of the echo dune increases gradually with the increase of the width of the nabkhas.In the early stage of dune formation,the height of the echo dune does not increase significantly with the height of nabkhas,and in the later stage,the height of echo dune increases gradually with the increase of nabkhas height.2)The wind speed is the minimum when echo dune vortex trough airflow recoils,whereas the wind speed is the maximum when the flanking airflow undergoes bypassing.3)The sediment transport is the largest at the flanks and the smallest at the vortex trough at five geomorphic parts of the echo dune.The closer the each geomorphic part is to the horizontal ground,the greater the sediment transport is.The eigenvalueλof wind-sand flow is greater than 1 in all five geomorphic sites,and wind erosion and transport processes dominate in each geomorphic site,greater scrub thinning or dieback can cause dissipation to occur in the echo dune.4)The sandy material on the surface of the echo dunes consists mainly of very fine sand,fine sand,and extremely coarse silt.The greater the wind speed is,the bigger the sand particles that are carried by the wind-drift sand are.The particles carried by the wind on the flank are the biggest,and the particles carried by the wind on the leeward slopes of nabkhas are the smallest.The average grain size of the surface sand of the echo dunes is coarser than that of the nabkhas.The morphological characterist

关 键 词:绿洲-沙漠过渡带 回涡沙丘 形态指标 输沙量 粒度特征 

分 类 号:P931[天文地球—自然地理学]

 

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