| 季节性冻土区包气带水汽热耦合运移研究进展 |
| |
| 引用本文： | 郑策,高万德,陈云飞,卢玉东,刘秀花.季节性冻土区包气带水汽热耦合运移研究进展[J].农业工程学报,2022,38(24):110-117. |
| |
| 作者姓名： | 郑策 高万德 陈云飞 卢玉东 刘秀花 |
| |
| 作者单位： | 1. 长安大学水利与环境学院，西安 710064；2. 长安大学旱区地下水文与生态效应教育部重点实验室，西安 710064 |
| |
| 基金项目： | 国家自然科学基金资助项目(42202279、41877179)；中国博士后科学基金(2022M720536) |
| |
| 摘 要： | 季节性冻土区占据中国超过一半的国土面积，冻融作用会显著改变土壤性质与包气带水、热传输过程，并且由于季节性冻土广泛分布在干旱半干旱地区，温度与气态水对于土壤水分运移影响显著，开展水汽热耦合研究不仅更符合季节性冻土区实际情况，同时对于揭示土壤水循环机制十分关键。本文综述了包气带水汽热耦合运移理论的提出与发展历程，阐述了季节性冻融作用对水汽热耦合运移研究中水力参数及水分相态转化过程的影响，探讨了水汽热耦合模型适用性，并归纳总结了温度梯度驱动下气态水运移规律及其重要性。最后，对该领域尚需加强研究的方向提出看法与建议，以期为深化包气带水汽热耦合运移理论以及解决季节性冻土区相关实际问题提供科学依据。
|
| 关 键 词： | 包气带 水汽热耦合运移 水文循环 数值模拟 季节性冻土区 |
| 收稿时间： | 2022/8/21 0:00:00 |
| 修稿时间： | 2022/10/10 0:00:00 |
Review of coupled water, vapor, and heat transport of the vadose zone in the seasonal frozen soil region |
| |
| Zheng Ce,Gao Wande,Chen Yunfei,Lu Yudong,Liu Xiuhua.Review of coupled water, vapor, and heat transport of the vadose zone in the seasonal frozen soil region[J].Transactions of the Chinese Society of Agricultural Engineering,2022,38(24):110-117. |
| |
| Authors: | Zheng Ce Gao Wande Chen Yunfei Lu Yudong Liu Xiuhua |
| |
| Institution: | 1. School of Water and Environment, Chang''an University, Xi''an 710064, China; 2. Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of Ministry of Education, Xi''an 710064, China |
| |
| Abstract: | Abstract: Seasonal frozen soil regions occupy more than half of China''s land surface, and the freeze-thaw process significantly change soil properties and water and heat transfer process in the vadose zone. Since most of the seasonal frozen regions belong to arid and semi-arid areas, soil is usually in dry condition, and temperature and water vapor have a significant impact on soil moisture in this region. During the past several decades, the significant effect of vapor flow on soil water movement for both freezing and non-freezing periods have been gradually recognized. Conducting the research of coupled water, vapor, and heat transport is not only suitable for actual conditions of seasonal frozen soil regions, but also crucial for revealing the mechanism of soil hydrological cycle. The coupled water, vapor, and heat transport theory was firstly proposed by Philip and de Vries, and they divided the total soil water flux into four components, including the liquid water flux and water vapor flux driven by water potential and temperature gradients, respectively. Since then, extensive researches about the coupled transport have been carried out and related theory are continuously improved. When soil is frozen, liquid water, vapor, and ice coexist in the unsaturated zone. The influence of phase changes between liquid water and ice on the coupled water, vapor, and heat transport is mainly in two aspects. On the one hand, the calculation methods of several hydraulic parameters are significantly affected, such as the soil freezing curve and hydraulic conductivity for liquid water, which are critical for understanding the hydrological cycle process. On the other hand, the spatial and temporal distribution of soil moisture in the vadose zone is dominated by seasonal freeze-thaw process as well. With the variations of soil temperature, the unfrozen water content and ice content change accordingly. Due to the increasing computational capacity and improving simulation accuracy, numerical simulation has gradually become the main approach for related studies. Influenced by the ice-water phase change, the establishment of coupled numerical model faces great challenges. Through reasonable simplification, establishing appropriate coupling model is crucial to numerical simulation. Based on the simulation results by different models, the underlying mechanism of coupled water and vapor flow is gradually revealed. Effected by the relatively low soil moisture and large temperature gradient in the shallow layer, vapor flux become a significant part in soil water movement, usually accounting for 10%-30% of the total water flux. Since the liquid water flow is impeded due to the presence of ice, the importance of vapor flow become more significant during the freezing period. In order to provide scientific basis for deepening the theoretical research and solving the practical problems related to seasonal frozen soil areas, some research interests that needs to be strengthened in this field are put forward. First, since soil water is critical for vegetation growth in fragile ecological areas, the condensation and accumulation of water vapor can help vegetation overcome soil drought and freezing stress and is of great significance for maintaining desert vegetation ecosystem. By coupling the vegetation module with the proposed coupled water, vapor, and heat model, further studies will allow us to explore the specific impact of liquid water and vapor to surface vegetation in seasonal frozen region. Second, the coupled transport of liquid water and vapor affect many engineering construction activities as well, such as frost heave in railway embankments caused by continuous liquid water and vapor transport from deep soil layer. By strengthening in-situ monitoring and simulating research, the detailed process of liquid and vapor transport below the surface impermeable layer can be revealed, thus providing scientific basis for disaster prevention and control during the freeze-thaw process. |
| |
| Keywords: | vadose zone coupled water vapor and heat transport hydrological cycle numerical simulation seasonal frozen soil region |
|
| 点击此处可从《农业工程学报》浏览原始摘要信息 |
| 点击此处可从《农业工程学报》下载免费的PDF全文 |
|
