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沙质草原槽形风蚀坑形态动力学研究

发表时间:2008-07-15  浏览量:1362  下载量:504
全部作者: 王帅,哈斯
作者单位: 浙江省水利河口研究院;北京师范大学资源学院,环境演变与自然灾害教育部重点实验室
摘 要: 对呼伦贝尔沙质草原地区槽形风蚀坑表面气流的观测结果显示:当气流进入风蚀坑,速度明显降低,在坑内的前1/2距离,风速较低,然后逐渐加速,在坑长3/4处,速度达到最高,但在坑后积沙坡脚处,由于气流遇阻且辐散的原因,速度再次降低,出现停滞现象,直至积沙坡顶才逐渐恢复。风蚀坑侧壁是由气流被吸入的过程侵蚀的,气流在坑内聚集加速从而侵蚀坑底。当斜向经过风蚀坑时,气流一般是从风向方的侧壁被吸入风蚀坑,由于侧壁坡度较陡,气流在进入过程中形成分离流,到达对面侧壁后形成反向回流造成进入侧的侧壁被侵蚀,而对面侧壁上有沙物质沉积的现象。气流在坑内前部形成螺旋流,在坑底后部形成高速流,积沙坡脚减速后又逐步恢复溢出风蚀坑。
关 键 词: 自然地理学;呼伦贝尔沙质草原;槽形风蚀坑;表面气流
Title: Morphology dynamics of trough blowout in sandy grassland
Author: WANG Shuai, HASI Eerdun
Organization: Zhejiang Institute of Hydraulics and Estuary;College of Resources Science and Technology,Key Laboratory of Environment Change and Natural Disaster, the Ministry of Education of China,Beijing Normal University
Abstract: Blowouts are the best surface expressions of the aeolian processes responding to regional climatic changes and human activities, it is also the driving force of grassland landscape heterogeneity. When the wind approaches the trough blowout parallel to the throat orientation, the velocity becomes slow because of the expansion, and until jet usually occurs in the 3/4 of the central line of the deflation basin, this is the result of the fact that more and more flow is sucked into the blowout, and the rim of the blowout is usually eroded by this process, therefore flow deceleration and expansion occurs upon the depositional lobe, and the previous condition reoccurs on the crest. When the wind approaches the blowout obliquely, the flow is usually extremely turbulent and large spiral vortices are commonly seen, flow is sucked into the blowout from the sidewall where wind enters, because the erosional wall is very steep, so the flow becomes return flow to erode the entering side wall and make the sands sedimented on the opposite wall. Trough blowout morphologies are explained as a function of these flow patterns.
Key words: physical geography; Hulun Buir sandy grassland; trough blowout; surface airflow
发表期数: 2008年11月第13期
引用格式: 王帅,哈斯. 沙质草原槽形风蚀坑形态动力学研究[J]. 中国科技论文在线精品论文,2008,1(13):1455-1459.
 
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