非贯穿型热喀斯特湖下部及其周围多年冻土特征

基于对青藏高原北麓河盆地天然形成的湖塘下部及其周围地温的监测分析, 结果表明该湖塘为非贯穿型热喀斯特湖. 湖塘下部多年冻土上限变化较大, 湖岸过渡带及天然场地多年冻土上限基本保持不变. 随着远离湖塘中心, 湖塘下部及其周围多年冻土含冰量依次升高, 地温年变化深度依次降低, 年平均地温依次降低. 观测期内, 湖塘下部浅层多年冻土地温在逐渐升高, 深部土体地温基本保持不变; 湖岸过渡带及天然场地下部多年冻土地温基本保持不变. 天然场地多年冻土地温明显低于湖塘下部土体地温.

Characteristics of Permafrost under a Nonpenerative Thermokarst Lake in Beiluhe Basin on the Tibetan Plateau

The characteristics of permafrost beneath a lake in the Beiluhe basin on the Tibetan Plateau were studied based on the ground temperature monitoring.The result shows that the monitored lake did not penetrate through the permafrost.During 2009 to 2010,the permafrost table beneath the lake varied greatly,while the permafrost table beneath the nearby natural alpine meadows was basically unchanged.Apart from the center of the lake,the volumetric ice contents of permafrost beneath and around the lake increased gradually,and the depth of zero annual amplitude of ground temperature and mean annual ground temperature decreased,respectively.During the observation,ground temperature of shallow permafrost increased yearly,but ground temperature of deep permafrost and beneath natural field still unchanged.Ground temperature of permafrost beneath natural field was obviously lower than that under the lake.