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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    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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History
  • Received:August 17,2023
  • Revised:October 09,2023
  • Adopted:October 10,2023
  • Online: January 27,2024
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