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为了进一步揭示毛乌素沙地含水量垂直变化的规律和风蚀意义,通过野外调查、采样、含水量测定、沙粒粒度测定和计算模拟,系统地研究了毛乌素沙地东南缘的3类沙丘含水量垂直变化的趋势,模拟了含水量垂直变化对输沙率垂直差异和沙丘形态演化的影响。结果表明:裸露流动沙丘迎风坡含水量在1.33%～3.79%之间波动;背风坡含水量在0.39%～5.04%范围内波动;丘间洼地含水量在2.12%～6.36%之间波动,裸露流动沙丘含水量的垂直变化可分为自上而下的5个沙层。灌木覆盖沙丘迎风坡的含水量在0.74%～11.92%之间波动;背风坡的含水量在0.89%～12.08%之间波动;丘间洼地的含水量在1.34%～9.24%之间波动,沙丘含水量的垂直变化存在差异明显的3个沙层。人工乔木覆盖沙丘的相对输沙率介于裸露流动沙丘和灌木覆盖沙丘之间。沙丘含水量2%～3%的垂直变化就能引起沙丘形态演化。在含水量垂直变化和沙丘背风坡和丘间洼地的阻滞下,沙丘形态演化存在3个阶段。在沙尘暴预报过程中需要考虑沙丘形态、沙丘含水量的垂直变化等因素对输沙率的影响,以提高预报工作的精度和可靠性。
In order to further reveal the vertical variation of water content and the meaning of wind erosion in Mu Us sandy land, three types of dune moisture content in the southeastern margin of Mu Us sandy land were systematically studied through field investigation, sampling, water content determination, grain size determination and calculation simulation. The vertical variation of water content and the vertical distribution of sediment yield and the evolution of dune morphology were simulated. The results show that the moisture content of the windward slope fluctuates between 1.33% and 3.79% in bare flowing sand dunes; the water content of leeward fluctuates within the range of 0.39% ~ 5.04%; the water content in the depression between the mounds fluctuates between 2.12% and 6.36% The vertical variation of water content in mobile sand dunes can be divided into five sand layers from top to bottom. The water content of the windward slope of shrub-covered sand dunes fluctuated between 0.74% and 11.92%, the leeward slope water fluctuated between 0.89% and 12.08%, the water content of the inter-depressions and valleys fluctuated between 1.34% and 9.24% Vertical changes in water content there are significant differences in the three sand layers. The relative sediment transport of man-made tree-covered dunes ranges between barely-flowing dunes and shrub-covered dunes. Vertical changes of dune moisture content of 2% to 3% can cause the evolution of dune morphology. There are three stages of morphological evolution of sand dunes under the vertical changes of water content and the blockage of leeward dunes and inter-mound depressions. Sandstorm forecasting process needs to consider the sand dune morphology, vertical changes in sand dune moisture content and other factors on the sediment transport rate in order to improve the accuracy and reliability of forecasting work.