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构成，探索了从沙柱上进行的蒸发经验，并在中国的沙漠地区观察到的气象数据。在后者中，将具有高确认性的NaCl溶液的浅水表暴露于以65％的湿度控制（夜间夜间）的环境空气，在该空气中，空气温度保持恒定（25°C）和550 W/m^使用潮湿的情况下，在潮湿的情况下，使用蒸气的信息在砂柱上分析了2个辐射。 A蒸发量大约是Thansa Thansa Thensa Thensa Thensa thensa thensa thensa thensa thensa thensa thensa thensa thensa thensa thensa thensa thensa at蒸发的来源是基本的含水层使用Atmostem中的热量 - 溶剂运动的模型成功地进行了，众所周知，该沙漠中的蒸发量几乎是在雨水中的相互作用，而溶液的尖峰出现了-10 cm - 浸润和土壤水蒸发。