| 青藏高原季节冻土区土壤冻融过程水热耦合特征 |
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| 引用本文： | 戴黎聪,柯浔,张法伟,杜岩功,李以康,郭小伟,李茜,林丽,曹广民.青藏高原季节冻土区土壤冻融过程水热耦合特征[J].冰川冻土,2020,42(2):390-398. |
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| 作者姓名： | 戴黎聪 柯浔 张法伟 杜岩功 李以康 郭小伟 李茜 林丽 曹广民 |
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| 作者单位： | 1.中国科学院 西北高原生物研究所，青海 西宁 810008;2.中国科学院大学，北京 100049 |
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| 基金项目： | 国家自然科学基金项目(41730752);青海省海南州小流域的综合治理及示范项目(2019-SF-152) |
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| 摘 要： | 青藏高原被誉为“中华水塔”， 其广泛分布的多年冻土和季节冻土在保证我国水资源安全上具有重要的地位。基于2015年7月 - 2016年6月青海海北站季节冻土的水热监测数据（土壤含水量为未冻水含量）， 分析了冻结深度的季节变化和冻融过程水热运移特征。结果表明： 各土层土壤温度与土壤水分含量变化均表现为“U”型。土壤温度变化规律与日平均气温基本一致， 但滞后于日平均气温的变化， 滞后时间取决于土层深度。与多年冻土冻融规律不同， 海北站季节冻土表现为单向冻结、 双向融化特征， 冻融过程大致可划分为三个阶段： 冻结初期、 冻结稳定期和融化期。同时， 季节冻土消融速率大于冻结速率， 且融化过程中以浅层土壤融化为主。在冻结过程中， 土壤水分沿上、 下两个方向分别向冻结锋面迁移， 各土层土壤含水量迅速下降。而在融化过程中， 各土层土壤含水量逐渐增加， 且在浅层土壤形成一个土壤水分的高值区。土壤冻融过程中未冻水含量与各土层土壤温度具有较好的相关关系， 且浅层土壤拟合效果优于深层土壤。本研究对揭示高原关键水文过程以及寒区水热耦合模型构建具有重要意义。
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| 关 键 词： | 季节冻土 季节变化 冻融过程 土壤温度 土壤水分 青藏高原 |
| 收稿时间： | 2018-07-09 |
| 修稿时间： | 2018-10-11 |
Characteristics of hydro-thermal coupling during soil freezing-thawing process in seasonally frozen soil regions on the Tibetan Plateau |
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| Licong DAI,Xun KE,Fawei ZHANG,Yangong DU,Yikang LI,Xiaowei GUO,Qian LI,Li LIN,Guangmin CAO.Characteristics of hydro-thermal coupling during soil freezing-thawing process in seasonally frozen soil regions on the Tibetan Plateau[J].Journal of Glaciology and Geocryology,2020,42(2):390-398. |
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| Authors: | Licong DAI Xun KE Fawei ZHANG Yangong DU Yikang LI Xiaowei GUO Qian LI Li LIN Guangmin CAO |
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| Institution: | 1.Northwest Institute of Plateau Biology，Chinese Academy of Sciences，Xining 810008，China;2.University of Chinese Academy of Sciences，Beijing 100049，China |
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| Abstract: | The Tibetan Plateau is known as the “Chinese water tower”， where widely distributed permafrost and seasonally frozen soil， which playing an important role in ensuring the safety of water resources in China. Here， based on seasonally frozen soil and hydro-thermal data sets （the soil water content is unfrozen water content） from July 2015 to June 2016 in Haibei Station， Qinghai， we analyzed the seasonal variation of frozen depth and the characteristics of hydro-thermal coupling during freezing-thawing process. The results show that： Both soil temperature and soil water content profiles display a U-shape， indicating that there is a consistency between soil temperature and soil water content. The soil temperature profile shows a similar changing trend with mean air temperature， but the variation in mean air temperature is greater than the variation in soil temperature. Moreover， the change of soil temperature has lagged behind the change of mean air temperature， and the lag time depends on the depth of soil. The seasonal freezing-thawing process can be divided into three periods， i.e.， initial freezing period， stable freezing period and thawing period； and the soil freezing-thawing process is characterized by unidirectional freezing and bidirectional thawing. Moreover， the thawing rate is greater than the freezing rate， and in thawing process the thawing from surface downwards is the main. During freezing process of soil， the unfrozen soil water migrates to the frozen front， leading to a decline for soil water content across different soil layers. However， the soil water content in shallow soil decreases more than that in deep soil. During thawing process of the frozen soil， the unfrozen soil water content across different soil layers increases successively. In addition， a high water content region is observed in shallow soil layers. There is a good correlativity between unfrozen water content and soil temperature across different soil layers during freezing process， and the correlation is better in shallow soil than in deep soil. This study would be useful for revealing the key hydrological process of plateau and constructing the hydro-thermal coupling model in cold regions. |
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| Keywords: | seasonally frozen soil seasonal variation freezing-thawing process soil temperature soil water content Tibetan Plateau |
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