| Desert and Desertification |
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| Interaction between Airflow and Shape of Saucer Blowout in Sandy Grassland |
| LI Shuang-quan1,2, Hasi Eerdun1, DU Hui-shi1, ZHANG Ping1, WU Xia1, YANG Yi1 |
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Abstract The long axis direction of saucer blowouts is WNW-ESE in Hulun Buir sandy grassland. According to the angle between wind direction and the blowout's long axis direction, airflows could be classified as perpendicular flow, left oblique flow, right oblique flow and axis-parallel flow. Field observations show that right oblique flow and perpendicular flow result in blowout's lateral expansion and deepening; left oblique flow and axis-parallel flow lead to sand outward transportation and blowout extending longitudinally. Right oblique flow and perpendicular flow can form clockwise perpendicular whirl in south margin of the saucer blowout; axis-parallel flow and left oblique flow can form anticlockwise perpendicular whirl in its northwest margin. Along the long axis direction of the saucer blowout, air flow separates and decelerates when it approaches the blowout's margin, then re-attaches at the bottom of the blowout, and then accelerates and climbs along the outlet slope till the top of the dune, lastly diffuses and decelerates in the leeward of the dune behind the saucer blowout. In cross section or arc section of the saucer blowout, airflow monotonicly increases or reduces. Deposition process principally dominated the blowout during observation period. The intensity of erosion and deposition is determined by resultant sand-transporting potential, while the angle between resultant sand-transporting potential direction and the long axis direction determines the spatial distribution pattern of erosion and deposition.
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Received: 06 December 2011
Published: 20 September 2012
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| [1]Hesp P A.Flow dynamics in a trough blowout[J].Boundary-Layer Meteorology,1996,77:305-330.[2]庄燕美,哈斯.沙丘风蚀坑形态与动力过程研究进展[J].干旱区地理,2005,25(5):632-637.[3]朱震达,吴正,刘恕,等.中国沙漠概论[M].北京:科学出版社,1980.[4]吴正.风沙地貌学[M].北京:科学出版社,1987.[5]Hesp P A,Pringle A.Flow behaviour in a trough blowout,Tangimoana,New Zealand[J].Journal of Coastal Research,2001,34(Special Issue):597-601.[6]Hesp P A.Foredunes and blowouts:Initiation,geomorphology and dynamics[J].Geomorphology,2002,48:245-268.[7]Hugenholtz C H,Wolfe S A.Form-flow interaction of an Aeolian saucer blowout[J].Earth Surface Processes and Landforms,2009,34:919-928.[8]阎旭,张德平,夏显东,等.呼伦贝尔沙质草原风蚀坑形态发育模式分析[J].中国沙漠,2009,29(2):212-218.[9]张德平,孙宏伟,王效科,等.呼伦贝尔沙质草原风蚀坑研究（Ⅱ）发育过程[J].中国沙漠,2007,27(1):212-218.[10]王帅,哈斯,张军,等.呼伦贝尔沙质草原碟形坑表面气流及其意义[J].中国沙漠,2007,27(5):745-749.[11]王帅,哈斯.呼伦贝尔沙质草原槽形风蚀坑表面气流特征[J].中国水土保持科学,2007,7(2):80-85.[12]Jackson P S,Hunt J C R.Turbulent wind flow over a low hill[J].Quarterly Journal of the Royal Meteorological Society,1975,101:929-955.[13]Fryberger S G.Dune form and wind regime[M]//McKee E D.A Study of Global Sand Seas.USGS Professional Paper.Washington D C:U S Geological Survey and United States National Aeronautics and Space Administration,1979,1052:137-169.[14]史培军.试论科尔沁南部大青沟地区沙漠化土地的地表形态特征及发育过程[J].内蒙古师范大学学报,1986,1(1):43-54.[15]Taylor P A,Mason P S,Bradly E F.Boundary-layer flow over low hills[J].Boundary-layer Meteorology,1987,39:107-182.[16]Lancaster N.Geomorphology of desert Sand Dunes[M].London:Routledge,1995:485.[17]Bullard J E,Wiggs G F S,Nash D J.Experimental study of wind directional variability in the vicinity of a model valley[J].Geomorphology,2000,35:127-143.[18]Wiggs G F S,Bullard J E,Garvey B,et al.Interactions between airflow and valley topography with implications for aeolian sediment transport[J].Physical Geography,2002,23:366-380.[19]Garvey B,Castro I P,Wiggs G F S,et al.Measurements of flows over isolated valleys[J].Boundary-Layer Meteorology,2005,117:417-446.[20]Frank A,Kocurek G.Towards a model of airflow on the lee side of aeolian dunes[J].Sedimentology,1996,43:451-458.[21]Walker I J,Nickling W G.Simulation and measurement of surface shear stress over isolated and closely spaced transverse dunes in a wind tunnel[J].Earth Surface Processes and Landforms,2003,28:1111-1124.[22]王训明,董治宝,赵爱国.简单横向沙丘表面物质组成、气流分布及其在动力学过程中的意义[J].干旱区资源与环境,2004,18(4):29-33.[23]Baddock M C,Livingstone I,Wiggs G F S.The geomorphological significance of airflow patterns in transverse dune interdunes[J].Geomorphology,2007,87:322-336. |
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2012, Vol. 32 
