基于地貌分类对祁连山大通河源区多年冻土地下冰储量估算

Based on geomorphic classification to estimate the permafrost ground ice reserves in the source area of the Datong River,Qilian Mountains

多年冻土地下冰作为一种特殊的存在形式,对高原生态、冻土环境以及冻土工程建设等都有深刻影响,但是目前对于青藏高原地下冰储量的研究很少。以祁连山中东部大通河源区为例,基于源区地貌分类、冻土分布等研究,利用源区多年冻土钻孔数据和公路地质勘测资料,在水平和垂直两个方向上估算了多年冻土层地下冰储量。计算表明:大通河源区多年冻土层2.5~10.0m深度范围内地下冰总储量为(11.70±7.24)km^(3),单位体积含冰量为(0.396±0.245)m^(3)。其中冰缘作用丘陵和冰缘湖沼平原等地貌区含冰量较高,而冰缘作用台地、冲积洪积平原则含冰量较低。在垂向上多年冻土上限附近含冰量最高,并随深度增大而缓慢减小。随着未来气候变暖、多年冻土退化以及环境变化,准确把握多年冻土区地下冰储量和分布特点对生态、水文地质、地质灾害预估、冻土工程建设具有深远意义。

The ground ice in permafrost is meaningful for studying permafrost environment,ecology and frozen soil engineering.However,there is not detailed study of it in the Tibetan Plateau.Taking the source areas of the Datong River in the Qilian Mountains as an example,based on the geomorphic classification,permafrost distribution,borehole data and geological survey data,the ground ice reserve in the depth range of 2.5~10.0 m of the permafrost is estimated in both horizontal and vertical directions.The spatial distribution characteristics of the ground ice in the source areas of the Datong River also discuss.It is found that in the depth range of 2.5~10.0 m,the total volume of ground ice is about(11.70±7.24)km^(3),and the ground ice content per m^(3)soil is about(0.396±0.245)m^(3).In the horizontal direction,periglacial lacustrine plain and periglacial hill contain more ice,but erosional platform and alluvial-proluvial plain contain less ice.In vertical direction,the amount of ice is more near the permafrost table and decreases slowly downwards.The study of ground ice reserves is of great significance in ecological,hydrogeological,frozen ground construction,as well as useful for thawing settlement prediction and other geological hazard prediction.