Relationships between vapor condensation, evaporation and salinization near ground surfaces in arid and semi-arid areas.

干旱和半干旱地区近地表水汽凝结、蒸发和盐化之间的关系。

基本信息

批准号：
11650536
负责人：
SHIMOJIMA Eiichi
金额：
$ 2.05万
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：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650536/
关键词：
arid-and seim-arid areas evaporation vapor condensation salinization experiment numerical simulation 観測データ

项目摘要

By paying attention to the condensation of atmospheric vapor, the relation between soil-surface evaporation and salinization in arid/semi-arid areas was explored through an evaporation experiment from a sand column and a numerical simulation to meteorological data observed in a desert area in West China (HEIFE).Using air-dried dune sand for HEIFE (Case A) and a fine silica sand (Case B), sand columns were set up on the balance, where only in the latter case, a shallow water table of NaCl solution with a high concentration was set. The columns were exposed to ambient air controlled at 65% humidity (corresponding to nighttime) and at 20% (daytime) alternately, where the air temperature is kept constant (25℃) and 550 W/m^2 of heat radiation was applied on the sand surface only at the dry air stage. Locations and movements of the evaporation and condensation zone for both cases were analyzed using information on vapor in the sand columns measured by humid-cups. For Case B the condensation amount at the wet stage was almost equal to the evaporation one at the dry stage, while for Case A, the evaporation was about ten times larger than the condensation and source of its surplus evaporation was the underlying aquifer. Soil water ahead of the evaporation front for Case B was chemically saturated and its concentration behind the front decayed exponentially with depth, while salinization for Case A was much lower.A numerical simulation using a model of heat-moisture-solute movement in the atmosphere-land system was successfully undertaken. And it was known that source of evaporation in that desert was almost rainfall and a spike of solute concentration profiles observed at 〜10 cm deep from the ground surface appeared through the interaction between rain-infiltration and soil-water evaporation.

通过关注大气蒸气的凝结，通过从沙柱上的经济实验和在中国的沙漠地区观察到的气象数据，探索了土壤表面经济与盐水的盐水之间的关系，并通过经济实验进行了经济实验，探索案例，设置了具有高浓度的NaCl溶液的浅水表。将柱暴露于以65％的湿度（对应于夜间）和20％（白天）的环境空气中，而空气温度保持恒定（25℃），并且仅在干燥空气阶段的砂表面上施加恒定的热辐射。使用潮湿杯测量的沙柱中的有关蒸气的信息分析了两种情况的经济和凝结区的位置和运动。对于案例B，湿阶段的冷凝量几乎等于在干旱阶段的经济状况，而对于案例A来说，经济大约是冷凝水的十倍，其盈余经济的来源是基础含水层。案例B的经济前方的土壤水是化学饱和的，其浓度是指数型的，而案例A的盐分化却低得多。使用大气层系统中的热 - 摩斯裂变模型的数值模拟成功地进行了成功。众所周知，那个沙漠中的经济来源几乎是降雨，并且在距地面深约10厘米处观察到的溶质浓度概况的尖峰通过雨水浸润和土壤水经济之间的相互作用出现。