|HU Xiaoying,SHENG Yu,WU Jichun,LI Jing,CAO Wei.Hydrothermal processes of thermokarst ponds in the Tibetan Plateau and its thermal impact on the underlying permafrost. J. Lake Sci.2018,30(3):825-835. DOI:10.18307/2018.0324
|以青藏高原查拉坪地区一处热融湖塘（40 m×50 m，最大深度为1 m）为研究对象，由实测数据对比分析了热融湖塘与天然地表相同深度的温度变化特征.结果表明：与天然地表相比，热融湖塘融化时间长，冻结时间短，且存在接近4℃的水温变化；受太阳辐射及热对流的影响，垂向水温梯度仅在水表从4℃降温及冻结阶段较大，其余时段接近0；湖底年均温度比相同深度的天然地表高约6.4℃，湖底下部存在约14 m深随时间发展的融区，土体吸热增大，放热减小；热融湖塘2.5~3.0 m土体的年内热交换为19592.0 kJ/m2，约是天然地表的230倍，其中吸热量及放热量分别为后者的1.4倍及8.7%.湖塘下部的融化夹层是深层冻土的主要热源，湖塘对下部土体放热的抑制作用是湖塘对土体产生热影响的主要原因.
|关键词: 热融湖塘 水热过程 地温梯度 融化夹层 热交换 青藏高原
|Hydrothermal processes of thermokarst ponds in the Tibetan Plateau and its thermal impact on the underlying permafrost
HU Xiaoying1,2, SHENG Yu1, WU Jichun1, LI Jing1, CAO Wei1
1.State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, P. R. China;2.University of Chinese Academy of Sciences, Beijing 100049, P. R. China
|A thermokarst pond (40 m×50 m, the maximum depth is 1 m) in the Chalaping of Tibetan Pleatu was regarded as a research object. Based on the measured data, the temperature variations and characteristics of thermokarst pond and natural ground at the same depth were analyzed. The results indicated that, compared with the natural ground, the thermokarst pond had a longer thawed time, a shorter frozen time, and a special time with water temperature being about 4℃. Due to the solar short radiation and convective heat transfer, the water temperature gradient in vertical was large during the surface temperature being decreasing from 4℃ and in the frozen stage, and other stages the water temperature gradient in vertical was almost zero. The annual average temperature at the bottom of pond was higher about 6.4℃ than that at the same depth of the natural ground. Besides, there was a talik being about 14 m depth under the bottom of pond being developing with time, and the heat absorbed and released of soil under the pond were increased and decreased, respectively. The heat absorbed from the depth of 2.5 to 3.0 m under the thermokarst pond was about 19592.0 kJ/m2 being about 230 times of that under the natural ground,the heat absorbed was 1.4 times of the natural ground, but the heat released was only 8.7% of the natural ground. So, the talik was the main heat resource to the deeper permafrost, and the thermal impact of thermokarst pond on the permafrost underlying was due to the decrease of heat released from the soil.
|Key words: Thermokarst pond hydrothermal processes gradient of ground temperature talik heat exchange Tibetan Plateau