1 Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China;
2 Dunhuang Gobi and Desert Ecology and Environment Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Dunhuang 736200, China;
3 Gansu Center for Sand Hazard Reduction Engineering and Technology, Lanzhou 730000, China
Morphology and formation mechanism of sand shadow dunes on the Qinghai-Tibet Plateau
1 Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China;
2 Dunhuang Gobi and Desert Ecology and Environment Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Dunhuang 736200, China;
3 Gansu Center for Sand Hazard Reduction Engineering and Technology, Lanzhou 730000, China
摘要 The formation and development of dunes depend on wind-blown sand movement which is affected by the characteristics of sand material, topography, wind regimes and other factors. In this paper, we investigated two sand shadow dune groups in Shigatse and Za’gya Zangbo of Tibet and an individual dune in Da Qaidam of Qinghai, and analyzed their topographies and morphologies, and the physical characteristics of the sand, wind regime and sand transport. Formed under harsh conditions behind hills, these mature sand shadow dunes are hundreds of meters long, have significant ridges and crescent dunes downwind, and have a hill pass on one or both sides. Wind tunnel experiments revealed that the hill gap and wind velocity are important factors in the formation of these dunes. Sand shadow dunes formed only when the gap spacing is two-thirds of the hill height. When wind velocities are 20 m/s, the sand body is divided into two parts. The hill pass allows the transport of sand by wind, creating a “narrow-pipe effect”, which causes the transported material to gradually accumulate in the center of the shadow zone. We observed that the following are needed for sand shadow dunes to form: (1) strong winds, sufficient sand, suitable obstacles and a dry climate; (2) one or both sides of the obstacle forming the shadow zone must have a hill pass; and (3) the windward side of the obstacle must have a wide, flat area, providing adequate spacing for wind flow and transport of material and the leeward side must have a sufficiently broad, flat area to allow the release of the transported material. Research results on these newly discovered dunes on the Qinghai-Tibet Plateau could contribute to the understanding of dune geomorphology.
Abstract: The formation and development of dunes depend on wind-blown sand movement which is affected by the characteristics of sand material, topography, wind regimes and other factors. In this paper, we investigated two sand shadow dune groups in Shigatse and Za’gya Zangbo of Tibet and an individual dune in Da Qaidam of Qinghai, and analyzed their topographies and morphologies, and the physical characteristics of the sand, wind regime and sand transport. Formed under harsh conditions behind hills, these mature sand shadow dunes are hundreds of meters long, have significant ridges and crescent dunes downwind, and have a hill pass on one or both sides. Wind tunnel experiments revealed that the hill gap and wind velocity are important factors in the formation of these dunes. Sand shadow dunes formed only when the gap spacing is two-thirds of the hill height. When wind velocities are 20 m/s, the sand body is divided into two parts. The hill pass allows the transport of sand by wind, creating a “narrow-pipe effect”, which causes the transported material to gradually accumulate in the center of the shadow zone. We observed that the following are needed for sand shadow dunes to form: (1) strong winds, sufficient sand, suitable obstacles and a dry climate; (2) one or both sides of the obstacle forming the shadow zone must have a hill pass; and (3) the windward side of the obstacle must have a wide, flat area, providing adequate spacing for wind flow and transport of material and the leeward side must have a sufficiently broad, flat area to allow the release of the transported material. Research results on these newly discovered dunes on the Qinghai-Tibet Plateau could contribute to the understanding of dune geomorphology.
This work was supported by the National Natural Science Foundation of China (40930741) and National Basic Research Program of China (2012CB026105). The authors gratefully acknowledge the anonymous reviewers and the editor whose comments and suggestions were helpful in improving the quality of this paper.
通讯作者:
JianJun QU
E-mail: qujianj@lzb.ac.cn
引用本文:
JianHua XIAO, JianJun QU, ZhengYi YAO, YingJun PANG, KeCun ZHANG. Morphology and formation mechanism of sand shadow dunes on the Qinghai-Tibet Plateau[J]. 干旱区科学, 2015, 7(1): 10-26.
JianHua XIAO, JianJun QU, ZhengYi YAO, YingJun PANG KeCun ZHANG. Morphology and formation mechanism of sand shadow dunes on the Qinghai-Tibet Plateau. Journal of Arid Land, 2015, 7(1): 10-26.
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2015, Vol. 7 
