Thermal–moisture dynamics and thermal stability of active layer in response to wet/dry conditions in the central region of the Qinghai–Tibet Plateau,China  

作　　者：MingLi Zhang ZhiXiong Zhou Zhi Wen FengXi Zhou Zhao Ma BingBing Lei 

机构地区：[1]College of Civil Engineering,Lanzhou University of Technology,Lanzhou,Gansu 730050,China [2]State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environmental and Resources,Chinese Academy of Sciences,Lanzhou,Gansu 730000,China [3]Geological Hazards Prevention Institute,Gansu Academy of Sciences,Lanzhou,Gansu 730000,China [4]College of Civil Engineering,Lanzhou Jiaotong University,Lanzhou,Gansu 730070,China

出　　处：《Research in Cold and Arid Regions》2023年第1期27-38,共12页寒旱区科学（英文版）

基　　金：funded by the National Natural Science Foundation of China (No.42261028,No.41961010,No.41801033);the "Light of West China" Program for the Organization Department of the Central Committee of the CPC, etc. (Zhang Mingli);the Chinese Academy of Sciences "Light of West China" Program for Western Young Scholars;Industrial support program of higher education of Gansu province (2020C-40);Basic Research Innovation Group of Gansu province (20JR5RA478)

摘　　要：The amount of rainfall varies unevenly in different regions of the Qinghai-Tibet Plateau, with some regions becoming wetter and others drier. Precipitation has an important impact on the process of surface energy balance and the energy-water transfer within soils. To clarify the thermal-moisture dynamics and thermal stability of the active layer in permafrost regions under wet/dry conditions, the verified water-vapour-heat coupling model was used. Changes in the surface energy balance, energy-water transfer within the soil, and thickness of the active layer were quantitatively analyzed. The results demonstrate that rainfall changes significantly affect the Bowen ratio, which in turn affects surface energy exchange. Under wet/dry conditions, there is a positive correlation between rainfall and liquid water flux under the hydraulic gradient;water vapour migration is the main form under the temperature gradient, which indicates that the influence of water vapour migration on thermalmoisture dynamics of the active layer cannot be neglected. Concurrently, regardless of wet or dry conditions,disturbance of the heat transport by conduction caused by rainfall is stronger than that of convection by liquid water. In addition, when rainfall decreases by 1.5 times(212 mm) and increases by 1.5 times(477 mm), the thickness of the active layer increases by 0.12 m and decreases by 0.21 m, respectively. The results show that dry conditions are not conducive to the preservation of frozen soil;however, wet conditions are conducive to the preservation of frozen soil, although there is a threshold value. When this threshold value is exceeded, rainfall is unfavourable for the development of frozen soil.

关 键 词：Active layer Wet/dry conditions Qinghai-Tibet Plateau(QTP) Thermal-moisture dynamics Permafrost thermal stability Numerical modelling 

分 类 号：P642.14[天文地球—工程地质学]