Pattern analysis of a linear dune field on the northern margin of Qarhan Salt Lake, northwestern China

Abstract

In terms of formation mechanisms of linear dunes, there are open arguments for their widespread distribution and multi-morphological diversities. In order to clarify the formation mechanism of linear dunes of Qarhan Salt Lake, we used pattern analysis method to analyze the statistical characteristics and spatial variation of their pattern parameters. Except at the west-northwest margin, the pattern parameters showed regular spatial variation from the up-middle part towards the downwind end of the dune field. Based on the cumulative probability plots for inter-crest spacing and crest length, we divided the linear dunes into three groups, which corresponding to the three evolution stages of these dunes. The first group comprises erosional relics, with shorter crests, smaller inter-crest spacing and more random dune orientation. The second group comprises dunes whose sand supply is just sufficient to maintain stability and these dunes are approaching the net erosion stage. The crest length and inter-crest spacing of these dunes are much larger than those of the first group, and dune orientation is closer to the resultant drift direction (RDD). The last group comprises linear dunes that are still undergoing vertical accretion and longitudinal elongation, which follows the RDD of the modern wind regime. The presence of regular spatial variation of pattern parameters and a similar geometry with the vegetated linear dunes suggest that deposition and erosion coexist in the development and evolution of linear dunes of Qarhan Salt Lake, i.e. deposition predominates at the downwind end of linear dunes in the vertical accretion and longitudinal elongation stage, whereas erosion mainly occurs at the upwind end of linear dunes in the degradation stage. Therefore, the formation mechanism of linear dunes in Qarhan Salt Lake can be reasonably explained by the combination of depositional and erosional theories.

Influence of salinity and moisture on the threshold shear velocity of saline sand in the Qarhan Desert, Qaidam Basin of China: A wind tunnel experiment

“…In Qaidam Basin, saline sediment influences dune evolution and alters sand dune morphology (Rubin and Hesp, 2009;Wolfe and Hugenholtz, 2009;Rubin and Rubin, 2013;Dong et al, 2017;Xiao et al, 2017;Zhang et al, 2018). Although, there has been much research on the sediment and dune composition, wind conditions, dune patterns and the temporal aspects of dune formation (Rubin and Hesp, 2009;Zhou et al, 2012;Li et al, 2015Li et al, , 2016Zhang et al, 2018). The understanding of how salt and clay affect sediment transport and the formation of linear dunes is still not clear.…”

Source of aeolian dune sands on the northern margin of Qarhan Salt Lake, Qaidam Basin, NW China

“…The gobi surface is covered by gravels ( Figure 3g,h); hence, the sand and finer grain-size fractions are protected from wind deflation. Both the yardang corridor sands and the gobi sediments FIGURE 2 (a) Distribution of major landforms in the Qaidam Basin (modified from Chen & Bowler, 1985); (b) the wind regime (redrawn from Li, Dong, Qian, Zhang, et al, 2016a; DP is short for drift potential, RDP is short for resultant drift potential, RDD is short for resultant drift direction, VU is short for vector unit and is the drift potential in each wind-direction class); and (c) sample locations in the study area [Colour figure can be viewed at wileyonlinelibrary.com] could potentially serve as sources for the linear dune sands. We collected 13 sediment samples, including four linear dune sands (LD01-04), five yardang corridor sands (YD01-05), and four gobi surface sediments (GB01-04).…”

Wind regime for long-ridge yardangs in the Qaidam Basin, Northwest China

“…The Cenozoic sediments from the surrounding mountains have formed deposits as thick as 12 km, mostly in the form of alluvialfluviolacustrine-playa facies (Xia et al, 2001). These sediments have been reworked by wind to form vast yardang fields, gravel deserts (gobis), playas and salt crusts, saline lakes and salt marshes, and dune fields widely distributed throughout the basin (Li et al, 2015(Li et al, , 2016b. The basin is characterized by a convergent drainage system pattern, with rivers that originate from the surrounding mountains and feed saline lakes in the central basin.…”