基于倾斜摄影技术的戈壁灌丛沙丘形态反演及其对粉尘释放研究的意义

灌丛沙丘是广泛分布于西北干旱区的风沙地貌。戈壁上发育的灌丛沙丘在戈壁沙尘释放和固沙能力方面具有重要的指示意义和应用价值。本研究采用倾斜摄影技术对戈壁上的灌丛沙丘形态特征进行观测和提取,并分析沉积物特征,计算戈壁灌丛沙丘的固沙能力,为沙尘释放研究提供依据。结果表明:(1)戈壁上发育的灌丛沙丘有明显的空间分布格局,即主要分布在干河床的两侧和地势低洼地区。(2)戈壁灌丛沙丘在形态上和其他地表灌丛沙丘类似,但沙丘的长度、宽度、底面积、体积等小得多,而且参数之间具有明显的相关关系。(3)沉积物的累积概率曲线表现为三段式,跃移组分的粒度范围(50~700 μm)明显与以往研究不同。沙丘内部和表层的粉沙和黏土含量分别为4.47%和5.24%,从而说明灌丛沙丘能够捕获戈壁上释放的粉尘物质。(4)戈壁地区单个灌丛沙丘的粉尘释放量约0.05~0.08 m³,固沙能力最大可达18.71 m³。

Nebkhas geomorphology in the gobi desert using the unmanned aerial vehicle and tilt camera

Nebkhas are one of main geomorphology, which are widely distributed in arid region. At present, nebkhas geomorphology patterns and its environmental significance in the sandy desert, agriculture land and oasis had been well researched. However, there are little research on the nebkha dunes in the gobi desert. The nebkhas in the gobi desert can be used as one of index for dust emission and sand fixing capacity. Therefore, the unmanned aerial vehicle and tilt camera were used to measure nebhka dunes morphology and sand fixing capacity in the gobi desert. (1) The research shows the nebkha dunes have an obvious spatial distribution patterns that almost all nebkha dunes are distributed on both sides of the gullies and low-lying areas. (2) The morphology of nebkha dunes on the gobi desert is similar as sandy desert, oasis and agriculture land, but the height, length, width, area and volume are smaller. Moreover, there is a clear correlation between the parameters. (3) The cumulative frequency curve of the sediments in the inner and over nebkha dunes shows a distinct three-stage: suspended component (particle size <63 μm), saltation component (63-500 μm) and creep component (>500 μm). The particle size range of the saltation components (50-700 μm) is significantly different from previous studies, which reflects the difference of sand supply and sediment transport type. Silt and clay is about 5% in the inner and over the nebkha dunes, which indicats it is come from dust emission in the Gobi desert. (4) According to the content of the silt and clay, we can derive that the dust emission quantity of single nebkha in the gobi desert is 0.05-0.08 m³, and sand fixing capability can reach to 18.71 m³.