Study on the Relationship between Evaporation from Bare-Soil Surfaces and Salinization in Arid and Semi-Arid Areas

干旱半干旱地区裸土蒸发与盐碱化关系研究

• 批准号: 09650575
• 负责人: SHIMOJIMA Eiichi
• 金额: $ 1.86万
• 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: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650575/
• 关键词: evaporation from bare-soil; salinization; arid and semi-arid areas; experiment; numerical simulation

This research aims at clarifying the relation between evaporation from bare-soil surfaces and salinization in arid and semi-arid areas through an experiment and a numerical simulation. The following results were obtained.(1) In the experiment, dune sand in Western China was used for setting up a sand column and a controlled atmospheric condition (temperature, humidity and radiation) was applied on the upper surface of the column with initially uniform water content profile (field capacity). 1) Liquid water, water vapor and solute dissolved from soil particle behaved in a manner of similarity, and evaporation rate varied inversely as square root of time. 2) Application of radiation suppressed evaporation through a downward transport of vapor. 3) High salinization occurred in a dried zone ahead of the drying front lead descent of its vapor density but increase in resistance to the vapor transport owing to the crystallization was not seen. 4) Under the periodic atmospheric condition simulating night-time (non-radiation and moist air) and daytime (radiation and dry air), periodic occurrence of evaporation-condensation near the sand surface played an important role in the evaporation process.(2) A numerical simulation using a newly formed calculation-scheme for water and solute movement predicted characteristics of evaporation-salinization seen in the experiment, and its solutions became very useful information for understanding the evaporation-salinization process.

本研究旨在通过实验和数值模拟阐明干旱和半干旱地区裸土表面蒸发与盐碱化之间的关系。 (1)实验中采用我国西部沙丘沙搭建沙柱,并在沙柱上表面施加受控大气条件(温度、湿度和辐射),初步形成均匀的含水率剖面(田间容量)。 1）液态水、水蒸气和土壤颗粒溶解的溶质表现相似，蒸发速率与时间的平方根成反比。 2) 通过蒸汽的向下传输应用辐射抑制蒸发。 3)在干燥前沿之前的干燥区中发生了高度盐化，导致其蒸气密度下降，但没有看到由于结晶而导致的蒸气传输阻力的增加。 4）在模拟夜间（无辐射和潮湿空气）和白天（辐射和干燥空气）的周期性大气条件下，沙子表面附近周期性发生的蒸发-凝结在蒸发过程中发挥了重要作用。（2）利用新形成的水和溶质运动计算方案的数值模拟预测了实验中所见的蒸发-盐化特征，其解对于理解蒸发-盐碱化特征非常有用。 蒸发-盐化过程。