Morphological dynamics of a trough-shaped blowout on a fixed dune in China

IF 3.1 3区地球科学 Q2 GEOGRAPHY, PHYSICAL

Aeolian Research Pub Date : 2022-12-01 DOI:10.1016/j.aeolia.2022.100830

Yanguang Zhou, Eerdun Hasi, Jie Yin, Zhuoran Wang, Damuni Qing, Rina Hu, Zifeng Wu

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引用次数: 0

Abstract

The formation and development of blowouts is an important surface indication of sand drift activity in semiarid grassland areas; thus, an accurate understanding of their morphological evolution characteristics and dynamic processes is of significance for grassland desertification control. This study analyzed the long-term topographic change of a trough blowout developed on a fixed sand dune in the Otindag sandy land of China via ground measurements from 2011 to 2020 and examined the short-term airflow structure through field observations. The results indicated that the area of the deflation basin shows a state of continuous growth. The expansion of the deflation basin was most obvious on the western, southwestern and southern slopes, which is contrary to the regional prevailing wind direction. As airflow passes over the blowout, there is significant airflow steering with the change in topography, and the degrees of airflow steering and acceleration are determined by the direction of the approaching wind. Airflow expands and decelerates on the leeward side of the deflation basin, causing flow separation and producing a recirculation zone on the sheltered lee slopes. Based on a detailed analysis of the results, we suggest that the soil collapse and sand avalanches caused by vortices are the main reasons for the upwind expansion of the deflation basin. Collectively, these findings reveal a strong link between the blowout morphology and the airflow pattern.

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中国固定沙丘上槽状井喷的形态动力学

井喷的形成与发展是半干旱草原地区沙流活动的重要地表标志;因此，准确认识它们的形态演化特征和动态过程对草地沙漠化防治具有重要意义。通过2011 - 2020年的地面观测，分析了中国敖廷达沙地固定沙丘上槽状喷流的长期地形变化，并通过野外观测考察了槽状喷流的短期气流结构。结果表明，收缩盆地面积呈持续增长状态。坳陷盆地的扩张在西、西南和南坡最为明显，与区域盛行风向相反。气流经过喷口时，随着地形的变化，气流发生明显的转向，气流转向的程度和加速程度由接近风的方向决定。气流在泄放盆地的背风面扩张和减速，导致气流分离，并在避风的背风坡上产生再循环区。通过对结果的详细分析，我们认为涡旋引起的土壤崩塌和沙崩是收缩盆地逆风扩张的主要原因。总的来说，这些发现揭示了喷流形态和气流模式之间的紧密联系。

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来源期刊

Aeolian Research GEOGRAPHY, PHYSICAL-

CiteScore

7.10

自引率

6.10%

发文量

审稿时长

>12 weeks

期刊介绍： The scope of Aeolian Research includes the following topics: • Fundamental Aeolian processes, including sand and dust entrainment, transport and deposition of sediment • Modeling and field studies of Aeolian processes • Instrumentation/measurement in the field and lab • Practical applications including environmental impacts and erosion control • Aeolian landforms, geomorphology and paleoenvironments • Dust-atmosphere/cloud interactions.