Dynamic Changes of Typical Blowouts Based on High‐Resolution Data: A Case Study in Hulunbuir Sandy Land, China

Abstract

Blowouts are an important ground indication of wind-sand activity in the Hulunbuir grassland. They include two basic geomorphologic units, erosion depression and sand deposition, and three typical morphological types: saucer type, trough type, and compound type. In this study, the dynamic changes of typical blowouts within the past decade were analyzed via multiperiod highresolution remote sensing images. RTK was used to repeatedly measure the blowouts to obtain their high-precision 3D terrain data in 2010, 2011, and 2012. Short-term dynamic changes in 3D blowout morphology were carefully analyzed to discover the following.(1) From 2002 to 2012, the depressions of typical blowouts exhibited downwind extension and lateral expansion trends, as they continuously grew in size. Regarding the sand deposition zones, those of the saucer blowout grew continuously, while those of the trough and compound blowouts fluctuated between growth and contraction. (2) The erosion depression of saucer blowouts eroded downward and spread horizontally; that of trough blowouts first accumulated then eroded but also spread horizontally. The erosion depression of compound blowouts exhibited horizontal spreading accompanied with bottom accumulation. The sand deposition zones of all three types of blowouts exhibited decreasing length with increasing width and height.

Determinants and dynamics of blowouts in Hulun Buir sandy grassland, Inner Mongolia, China from 1959 to 2018

“…Based on previous studies of the developmental stages of blowouts (Gares & Nordstrom, 1995; Hesp, 2002; Hesp et al, 2016; Luo, Wang, Lu, et al, 2019; Luo, Wang, Shao, et al, 2019; Smith et al, 2017; Yang et al, 2017; Zhang et al, 2006), the blowouts in the Hulun Buir sandy grassland can be classified depending on their stage of development as aeolian bare lands, active blowouts (saucer‐shaped, cup‐shaped, and trough‐shaped), fixed blowouts, or decaying blowouts, as shown in Table 2.…”

“…From a geomorphological point of view, the aeolian bare sand in these areas includes both the depressions and the depositional lobes, that is the areas of exposed erosion and accumulation. Depressions and depositional lobes may be differently affected by changes in external factors, and these effects may vary in different development stages of the blowouts (aeolian bare lands and active, fixed, and decaying blowouts) (Gares & Nordstrom, 1995; Hesp, 2002; Hesp et al, 2016; Luo, Wang, Lu, et al, 2019; Luo, Wang, Shao, et al, 2019; Smith et al, 2017; Yang et al, 2017; Zhang et al, 2006). Therefore, changes in the scale of the depressions and the depositional lobes must be correlated with changes in environmental elements to more fully understand these processes.…”