| Research Articles |
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| Morphology and formation mechanism of sand shadow dunes on the Qinghai-Tibet Plateau |
| JianHua XIAO1,2, JianJun QU1,2,3*, ZhengYi YAO1, YingJun PANG1,2, KeCun ZHANG1,2 |
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 |
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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.
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Received: 25 November 2013
Published: 10 February 2015
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| Fund: 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. |
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| Bagnold R A. 1941. The Physics of Blown Sand and Desert Dunes. London: Methuen, 188–196.Beniston M, Diaz H F, Bradley R S. 1997. Climatic change at high elevation sites: an overview. Climatic Change, 36(3–4): 233–251.Bressolier C, Thomas Y F. 1977. Studies on wind and plant interactions on French Atlantic coastal dunes. Journal of Sedimentary Research, 47(1): 331–338.Cooke R U, Warren A. 1973. Geomorphology in Deserts. London: B T Batsford, 255–258.Cooper W S. 1958. Coastal Sand Dunes of Oregon and Washington. New York: Geological Society of America, 168–172.Elbelrhiti H, Claudin P, Andreotti B. 2005. Field evidence for surface-wave-induced instability of sand dunes. Nature, 437(29): 720–723.Elbelrhiti H, Andreotti B, Claudin P. 2008. Barchan dune corridors: field characterization and investigation of control parameters. Journal of Geophysical Research: Earth Surface, 113(F2): F02S15.Elbelrhiti H. 2012. Initiation and early development of barchans dunes: a case study of the Moroccan Atlantic Sahara desert. Geomorphology, 138(1): 181–188.Evans J R. 1962. Falling and climbing sand dunes in the Cronese (“Cat”) mountains, San Bernardino County, California. The Journal of Geology, 70(1): 107–113.Gunatilaka A, Mwango S B. 1989. Flow separation and the internal structure of shadow dunes. Sedimentary Geology, 61(1–2): 125–134.Ha S, Wang G Y. 2001. Characteristics of grain size over crescentic dunes in Shapotou, southeastern Tengger Desert. Journal of Desert Research, 21(3): 271–275. (in Chinese)Ha S, Zhuang Y M, Wang L, et al. 2006. Grain-size variation on a transverse dune and response to wind direction changes on southern edge of Mu Us Desert. Progress in Geography, 25(6): 42–51. (in Chinese)Hesp P A. 1981. The formation of shadow dunes. Journal of Sedimentary Research, 51(1): 101–112.Jackson P S, Hunt J C R. 1975. Turbulent wind flow over a low hill. Quarterly Journal of the Royal Meteorological Society, 101(430): 929–955.Lancaster N. 1995. Geomorphology of Desert Dunes. London: Routledge, 115–119.Lancaster N, Nickling W G, Neuman C K M, et al. 1996. Sediment flux and airflow on the stoss slope of a barchan dune. Geomorphology, 17(1–3): 55–62.Li S, Wang Y, Ha S, et al. 1997. Classification and development of aeolian sand landform in the Yurlung Zangbo valley. Journal of Desert Research, 17(4): 342–350. (in Chinese)Li Z S, Ni J R. 2000. A review of desert dune geomorphology. Journal of Sediment Research. 5: 73–81. (in Chinese)Liu X W, Li S, Shen J Y. 1999. Wind tunnel simulation experiment of mountain dunes. Journal of Arid Environments, 42(1): 49–59.Livingstone I, Wiggs G F S, Weaver C M. 2007. Geomorphology of desert sand dunes: a review of recent progress. Earth-Science Reviews, 80: 239–257.Luo W Y, Dong Z B, Qian G Q, et al. 2012a. A research review on aerodynamic effects of shelter fences. Journal of Desert Research. 32(4): 885–895. (in Chinese)Luo W Y, Dong Z B, Qian G Q, et al. 2012b. Wind tunnel simulation of the three-dimensional airflow patterns behind cuboid obstacles at different angles of wind incidence, and their sig-nificance for the formation of sand shadows. Geomorphology, 139–140: 258–270.Luo W Y, Dong Z B, Qian G Q, et al. 2014. Near-wake flow patterns in the lee of adjacent obstacles and their implications for the formation of sand drifts: a wind tunnel simulation of the effects of gap spacing. Geomorphology, 213: 190–200.Pidgeon I M. 1940. The ecology of the central coastal area of New South Wales. III. Types of primary succession. Proceedings of the Linnean Society of New South Wales, 65: 221–249.Pye K, Tsoar H. 1990. Aeolian Sand and Sand Dunes. London: Unwin Hyman, 89–93.Salisbury E. 1952. Downs and Dunes: Their Plant Life and Its Environment. London: G. Bell and Sons Ltd, 168–177.Shi P J, Wang J A. 1986. Aeolian sand grain size of statistical analysis in arid and semiarid area of China. Journal of Inner Mongolia Normal University: Natural Science Edition, 4: 12–21. (in Chinese)Tang J N, Su Z Z, Ding F, et al. 2011. The formation age and evolution of Kumtagh Desert. Journal of Arid Land, 3(2): 114–122.Tsoar H. 1983. Wind tunnel modeling of echo and climbing dunes. Amsterdam: Elsevier, 247–259.Tsoar H, Blumberg D G. 2002. Formation of parabolic dunes from barchan and transverse dunes along Israel's Mediterranean coast. Earth Surface Processes and Landforms, 27(11): 1147–1161.Wang X M, Dong Z B, Zhang J W, et al. 2004. Formation of the complex linear dunes in the central Taklimakan Sand Sea, China. Earth Surface Processes and Landforms, 29(6): 677–686.Wiggs G F S. 2001. Desert dune processes and dynamics. Progress in Physical Geography, 25(1): 53–79.Wu Z. 2003. Aeolian Landform and Sand Control Engineering. Beijing: Science Press, 261–266. (in Chinese)Yin D Y, Qu J J, Han Q J, et al. 2013. Wind-blown sand activity intensity in Cuonahu Lake section of Qinghai-Tibet Railway. Journal of Desert Research, 33(1): 9–15. (in Chinese)Zhao Y J. 1991. The influence of Mazhatag Mountain on wind sandy landforms in its two sides. Arid Zone Research, 8(1): 8–12. (in Chinese)Zhu Z D, Chen Z P, Wu Z, et al. 1981. Study on the Aeolian Geomorphology of the Taklimakan Desert. Beijing: Science Press, 110–112. (in Chinese) |
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