基于综合调查的西昆仑山典型区多年冻土分布研究

Permafrost Distribution in Typical Area of West Kunlun Mountains Derived from a Comprehensive Survey

西昆仑山位于青藏高原西北部,地势起伏大,气候干旱严寒.为了解其多年冻土分布状况,以219国道大红柳滩到奇台达坂之间的沿线区域作为西昆仑山典型区,以野外冻土钻探、坑探、物探为主要调查手段,综合分析该区域多年冻土分布的下界.对现场调查数据的初步分析表明,该区域多年冻土阳坡下界在海拔4 800m,阴坡下界在海拔4 650m,东西坡下界在海拔4 700m.依据上述冻土下界的分布规律,以数字高程模型为基础,通过ArcGIS软件建立了西昆仑山典型区的多年冻土分布模型,实现了对研究区域多年冻土分布的模拟.对该区域的研究结果表明:典型区内多年冻土的分布面积为3 136.3km2,占区域总面积的89.4%.结果与青藏高原冻土图在该区域的截图相比,多年冻土的面积略有增加.对比分析模拟图和截图后发现,基于实际调查的多年冻土模拟分布图更准确的描述了河谷的融区,而截图的多年冻土分布界限较为粗糙,缩小了喀喇喀什河支沟融区,人为放大了219国道大红柳滩到奇台达坂之间的宽谷融区.

The West Kunlun Mountains in the northwest of the Tibetan Plateau,where terrain undulates largely and climate is arid and frigid.In order to well understand the distribution of permafrost in the mountains,the section between Dahongliutan and Qitaidaban along the State Highway 219 was chosen as a typical area.Many survey methods were adopted,including drilling survey,geophysical prospecting and exploration pit.The lower boundary of permafrost was determined through comprehensive analysis of the survey data.The lower boundary of permafrost is 4 800 m a.s.l.in the south slopes,4 650 m a.s.l.in the north slopes,and 4 700 m a.s.l.in the east and west slopes.According to the lower boundaries in different orientations and the data of digital elevation map,permafrost distribution model in the typical area of the West Kunlun Mountains was established in the ARCGIS platform.The simulation results based on the model show that the permafrost area is 3 136.3 km2,accounting for 89.4 percent of the region.The simulated permafrost area is a little more than that derived from the Tibetan Plateau Permafrost Map（TPPM）.By comparing the two maps,the following differences are found： 1） the permafrost map derived from survey is able to describe the river talik more precisely than that from the TPPM;2） the river talik in the TPPM is far smaller than the actual talik derived from survey;3） seasonal frozen area in the wide valley between Dahongliutan and Qitaidaban was magnified in the TPPM.