大通河源区冻土地温模拟与分类特征分析

Modeling permafrost temperature distribution and analyzing zoning characteristics of permafrost in the source region of the Datong River

以大通河源区为研究区域,分析了植被对多年冻土分布的影响.以等效高程为基础,根据实测的多年冻土地温数据和植被调查数据,建立了不同植被类型条件下的冻土地温-等效高程关系模型.借助于TM遥感数据、DEM数据和GIS技术模拟了大通河源区植被覆盖区的多年冻土地温分布特征.以地温数据为基础,参照青藏高原多年冻土分带方案,对多年冻土的分类特征进行了研究.结果表明:大通河源区多年冻土年均地温为-8.66～1.72℃,多年冻土和季节冻土的面积比例分别为95%和5%,其中极稳定型、稳定型、亚稳定型、过渡型和不稳定型多年冻土各类型的面积比例依次为1%,12%,31%,35%和16%.

Based on the important impact of vegetation on permafrost development, the influence of vegetation on permafrost distribution was studied taking the source region of the Da-tong River Basin as the study area. Taking the calculated equivalent-elevations together with the measured ground temperatures of permafrost （at 15 m depth） and the vegetation samplingsas basis data, two equations between permafrost temperatures and equivalent-elevations suitable to different vegetated areas, alpine meadow and alpine swampy meadow, were construc-ted, and the spatial distribution of permafrost temperatures were modeled in the vegetated areas of the source region of the Datong River Basin using the equations in conjunction with the landsat TM data, DEM data and the GIS technique. The scheme for classifying the permafroston Qinghai-Xizang Plateau into zones was adopted to divide permafrost in the source region into zones according to the predicted permafrost temperatures, and thus the zoning characteristics ofeach type of permafrost were analyzed. The results show that the permafrost temperatures range from -8. 66 ℃ to 1.72 ℃ in the study area, and the areal percentages which permafrostand the seasonally frozen ground account for the total area are 95% and 5%. Permafrost is classified into five types： highly-stable, stable, sub-stable, transitional and non-stable with1%, 12%, 31%, 35% and 16% areal percentages, respectively.