Numerical Simulation Analysis of the Formation and Morphological Evolution of Asymmetric Crescentic Dunes

Huiwen Zhang, Changlong Li, Jianhui Zhang, Zhen Wu, Zhiping Zhang, Jing Hu, Lei Cao, Longlong Song, Jianping Ma and Bin Xiao
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Huiwen Zhang: National Forest Germplasm Resource Bank of Desert Plants in Minqin Desert Control Station of Gansu Province, Gansu Desert Control Research Institute, Lanzhou 733000, China
Changlong Li: National Forest Germplasm Resource Bank of Desert Plants in Minqin Desert Control Station of Gansu Province, Gansu Desert Control Research Institute, Lanzhou 733000, China
Jianhui Zhang: National Forest Germplasm Resource Bank of Desert Plants in Minqin Desert Control Station of Gansu Province, Gansu Desert Control Research Institute, Lanzhou 733000, China
Zhen Wu: Lanzhou Institute of Seismology of China Earthquake Administration, Earthquake Administration of Gansu Province, Lanzhou 730000, China
Zhiping Zhang: State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou 730070, China
Jing Hu: National Forest Germplasm Resource Bank of Desert Plants in Minqin Desert Control Station of Gansu Province, Gansu Desert Control Research Institute, Lanzhou 733000, China
Lei Cao: State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou 730070, China
Longlong Song: State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou 730070, China
Jianping Ma: State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou 730070, China
Bin Xiao: State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou 730070, China

Sustainability, 2022, vol. 14, issue 14, 1-23

Abstract: Generally, typical crescentic dunes in the ideal state are symmetrical, but it is difficult to form crescentic dunes with two perfectly symmetrical horns under actual conditions. Among many environmental factors, bidirectional winds, the size of sand particles, topography, epiphyte vegetation, and dune collision are important reasons for the asymmetric evolution of sand dunes. Few existing studies have revealed the mechanism of the morphological evolution of asymmetric crescentic dunes, especially in regard to the role of wind in a complex dune’s morphology. In this study, we used the Reynolds Averaged Navier-Stokes (RANS) and mass balance models to simulate the asymmetric forms and flow fields of crescentic dunes and analyzed the potential causes of the asymmetry among the above aspects. The results showed that: (1) the angle of the bidirectional winds significantly changed the structure of vortices around the sand dune; (2) for crescentic dunes with coarser sand, the deposit continuity was better, the extension of the single horn was maintained for a long time, and the extended horn took longer to die out; (3) the crescentic dune deformed according to the direction of the inclination of the terrain, and the shear stress of a dune on a slope was related to the slope, width, or height; (4) whether there was epiphytic vegetation on a dune’s surface had a great impact on the dune’s migration; (5) the collision position of two dunes determined the shape of the two dunes after fusion. The simulation results indicated that the spatial–temporal differences in sand flux, caused by changes in flow fields that were induced by various factors, determined the evolutionary shape of crescentic dunes. These results can provide a reference for the study of the erosion of surface flow fields on various dunes and for the prevention and control of wind and sand disasters in the Gobi Desert area.

Keywords: asymmetric crescentic dunes; morphological evolution; surface flow field; numerical simulation (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
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