新月形沙丘脊线处的风沙流结构

Aeolian Sand Structure at the Brink of Barchans

分析流动沙丘脊线处的风沙流结构对认识其形态-动力学过程至关重要,进而为干旱区绿洲保护和生态重建提供基础数据支撑和理论依据。利用传统的被动式集沙仪,分别对正风向与反风向情况下新月形沙丘脊线附近0~60 cm高度内的风沙运动进行观测,通过函数拟合方法分析风沙流结构。结果表明:正风向时,输沙量随高度增加符合幂函数递减的规律,气流对沙物质的输运集中在近地表30 cm高度内;反风向时,输沙量随着高度的增加先增加后减少,变化趋势近似符合双高斯函数,气流含沙量在30~50 cm高度内最多。

The aeolian sand structure at the brink of barchans is critical to the understanding of the dune morphodynamic process, and thus providing the basic data support and theoretical foundation for the protection and ecological reconstruction in arid regions. In the current study, the traditional passive sand-collectors are used to observe the sand movement at the height range of 0-60 cm above the barchan brink in the cases of positive and reverse wind directions respectively, and then the obtained mass flux density distribution curves are analyzed by means of function fitting. It is shown that the amount of sediment driven by the positive winds is a power function of height, and the mass transport mainly occurs in the height of 0-30 cm;Whereas in the case of reverse wind direction with the increase of height, the sediment amount increases first and then begins to monotonely decrease at the height of 30-50 cm the change trend approximately obeys the double Gaussian function.