草原干涸湖床地表粒度特征及其对沙尘释放的影响
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1.内蒙古农业大学沙漠治理学院;2.内蒙古财经大学旅游学院

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国家自然科学基金项目(面上项目,重点项目,重大项目)


Surface particle size characteristics of dry lake beds in grasslands and their effects on dust release
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College of Desert Control Science and Engineering,Inner Mongolia Agricultural University

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    摘要:

    [目的]为探究干涸湖盆典型地表风蚀过程以及盐碱尘暴形成的机理。[方法]以锡林郭勒盟阿巴嘎旗查干淖尔干涸盐湖为研究对象,从湖心到湖岸根据盐湖地表的动态演化过程选择4种典型地表(结皮地表、破碎地表、活化地表、沙化地表),分析从湖心到湖岸近地表土壤粒度分布特征、风速廓线以及输沙规律等,[结果](1)从湖心向湖岸延伸,地表0—2 cm沉积物颗粒粒配整体呈逐渐变粗的趋势,且以黏粒、粉粒为主;(2)干涸盐湖从湖心到湖岸风速整体呈降低的趋势,不同地表的风速廓线基本符合Karman的速度对数分布规律,且拟合效果较好(R2 > 0.9);(3)破碎地表上的输沙量最大,约是结皮地表的50倍,且由于有限沙尘供应,导致结皮地表的输沙率随高度变化呈现线性规律(R2 = 0.8),其他3种地表的输沙率随高度变化呈现指数函数形式(R2 > 0.97);(4)在近地表0—50 cm高度内,风沙流中携带的沙粒平均粒径在6~9 Φ,属于粉粒,分选性较差,偏度以负偏为主,峰态以中等和尖窄为主。[结论]整体来看,破碎地表上的风蚀作用最强,结皮地表上的风蚀作用最弱。可通过提高沙粒的临界启动风速阈值和下垫面的覆盖度等方式减弱该地区的风蚀作用。

    Abstract:

    [Objective] In order to explore the typical surface wind erosion process of the dry lake basin and the mechanism of the formation of saline-alkali dust storm. [Methods] Taking the Chagannaoer dry salt lake in Abaga Banner of Xilin Gol League as the research object, four typical surface ( crust surface, broken surface, activated surface and desertification surface ) were selected according to the dynamic evolution process of salt lake surface from the center of the lake to the shore of the lake. The characteristics of soil particle size distribution, wind speed profile and sediment transport law near the surface from the center of the lake to the shore of the lake were analyzed. [Results]The results show that : (1) From the center of the lake to the shore of the lake, the grain size of 0 - 2 cm sediment particles on the surface shows a trend of gradually thickening, and mainly clay and silt ; (2) The wind speed from the center of the dry salt lake to the shore of the lake showed a decreasing trend. The wind speed profiles of different surfaces basically conformed to the logarithmic distribution of Karman 's velocity, and the fitting effect was good (R2 > 0.9). (3) The amount of sediment transport on the broken surface is the largest, which is about 50 times that of the crust surface, and the sediment transport rate on the crust surface shows a linear law with the change of height due to limited dust supply (R2 = 0.8), and the sediment transport rate on the other three surfaces shows an exponential function with the change of height (R2 > 0.97). (4) At the height of 0~50 cm near the surface, the average particle size of the sand particles carried in the wind-sand flow is between 6 ~9 Φ, which belongs to the silt, and the sorting is poor. The skewness is mainly negative, and the kurtosis is mainly medium and sharp. [Conclusion]On the whole, the wind erosion effect on the broken surface is the strongest, and the wind erosion effect on the crust surface is the weakest. The wind erosion effect in this area can be weakened by increasing the critical starting wind speed threshold of sand particles and the coverage of underlying surface.

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  • 收稿日期:2023-08-17
  • 最后修改日期:2023-10-09
  • 录用日期:2023-10-10
  • 在线发布日期: 2024-01-27
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