Relationships between evaporation-precipitation and salinization in a semi-arid area

半干旱区蒸发降水与盐渍化的关系

基本信息

批准号：
13650574
负责人：
SHIMOJIMA Eiichi
金额：
$ 2.18万
依托单位：
Daido Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650574/
关键词：
semi-arid area evaporation from ground surface salinization sand column experiment numerical simulation

项目摘要

A relation between evaporation and salinization in a semi-arid area was explored through a column evaporation experiment and a numerical simulation.A sand column 100 cm long and 10 cm in diameter made using a sandy soil in Western Australia was installed on a balance, where via a draining process, a shallow water table (Case A) or a uniformly distributed water content profile in field capacity (Case B) was set. By exposing Its upper surface to ambient air controlled at 25℃and 20 % of RH, the evaporation experiment was started, where, when a solar radiation was simulated, a heat flux at 550 W/m^2 was applied on that surface. The following was recognized. Chemistry of soil-water formed through a rapid dissolution of sand particles was mainly Cl, Na^+, Mg^<2+> and showed a high concentration. Dryness in a zone near the sand surface, in particular, for Case B was more advanced and salinization was also much more developed, where the evaporation zone moved down to 2 cm deep (for Case A, 1 cm). For every case a crust was formed on the sand surface and its thickness for Case B was 5 mm after 40 days. Upward transport resistance for vapor generated by evaporation was estimated one-order of magnitude larger in the crust than that in fairly dried zone overlying that front. Only in the case that heat was applied, a downward movement of vapor appeared.Based on a vertically one-dimensional numerical model on moisture, vapor heat and a chemical component, the hydro-meteorological data observed over a sand dune in semi-arid area in Western China (HEIFE) were reproduced well after improvement on bulk coefficients of turbulent transport from surface, albedo and emissivity of infrared radiation. A characteristic of solute concentration profile observed there could be reproduced by 10-year calculation.

通过柱经济实验和数值模拟探索了经济与盐分之间的关系。在澳大利亚西部使用沙质土壤制成的沙列长100厘米，直径为10厘米，在平衡中安装了浅水土壤，通过排水过程，通过排水过程，浅水桌（情况A）或均匀分布的水内容概况在现场容量（案例）中（案例）（案例）（案例）。通过将其上表面暴露于在25℃和20％的RH的环境空气中，经济实验开始了，在模拟太阳辐射时，在该表面上施加了550 W/m^2的热通量。以下是认可的。通过砂颗粒快速溶解形成的土壤水的化学主要是Cl，Na^+，mg^<2+>，并且显示出高浓度。尤其是在沙子表面附近的区域中的干燥性，对于B病例B，盐度更高，盐度化也更加发达，经济区向下移至2厘米深（对于情况A，1厘米）。对于每种情况，在砂表面形成了地壳，其厚度B 40天后为5 mm。估计，在地壳中，经济产生的蒸气的向上抗性比在该方面的相当干燥的区域大的数量级要大。仅在施加热量的情况下，出现了蒸气的向下移动。基于在水分，蒸气热和化学成分的垂直一维数值模型上，在中国西部（Heife）的半干旱地区的沙丘上观察到的水力学数据在中国（Heife）（Heife）中得到很好的良好层面的隔离式散热器，并从表面上进行了良好的运输，并逐渐脱离了构成型的构成。观察到的可溶浓度谱的特征可以通过10年的计算来重现。