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湿沙层水分及其运移过程是沙漠地区水循环的重要环节。巴丹吉林沙漠高大沙山湿沙层规模巨大,本文对巴丹吉林沙漠高大沙山湿沙层水分特征进行了初步分析。结果表明:湿沙层水分具有区域相似性特征,含水量多小于3%;吸附水和沙粒空隙间的水汽是湿沙层水分两种主要的类型,沙粒粒级级配影响吸附水水量变化,两种水分在沙山垂直剖面上的运移过程及相互转化可能维持了湿沙层水分的相对平衡状态;沙丘表层形成的“逆温层”以及由此引起的沿沙丘表层向沙丘内部的热量传递,形成与湿沙层水分蒸发相反的空气运动方向,使得湿沙层水分在夏季晴朗的白天受到保护;夏季受温度梯度影响,湿沙层中的水汽和膜状水向沙山底部缓慢运移;冬季受温度梯度和水势的双重影响,沙山底部潜水面附近的水汽和膜状水向上缓慢运移,补给湿沙层;湿沙层水分来源包括大气降水、大气水汽、凝结水及地下水等。
Wet sand water and its migration process is an important part of the water cycle in desert areas. The wet sand layer in the high sand mountain of Badain Jaran Desert is huge in scale. The water characteristics of the wet sand layer in the high sand mountain of Badain Jaran Desert were preliminarily analyzed. The results show that the moisture content of wet sand has the characteristics of regional similarity, and the water content is less than 3%. The water vapor between the adsorbed water and the sand is the two main types of moisture in the wet sand layer. , The migration and mutual transformation of the two types of water in the vertical section of the sand hill may maintain the relative balance of moisture in the wet sand layer; the “inversion layer” formed on the surface of the sand dune, The internal heat transfer to form the direction of the air movement opposite to the moisture evaporation of the wet sand layer, so that the moisture in the wet sand layer is protected during the clear sunny day in summer. In summer, due to the temperature gradient, the water vapor and the film- The bottom of the sand gradually migrated slowly; in winter, due to the dual influence of temperature gradient and water potential, the water vapor and membrane-shaped water near the bottom of the sand bottom moved slowly upward to supply the wet sand layer; the moisture sources of the wet sand layer included atmospheric precipitation, atmospheric water vapor, Water and groundwater.