青藏高原西部区域多年冻土分布模拟及其下限估算

准确评估青藏高原西部多年冻土的空间分布及多年冻土下限深度情况对该区地下水资源利用、生态环境保护有重要意义.本文依托科技基础性工作专项“青藏高原多年冻土本底调查”在该区及周边取得的冻土调查资料,利用遥感数据和扩展地面冻结数模型模拟了该区多年冻土的空间分布,调查区的模拟验证表明该方法有较高的精度.在此基础上,根据有限的地温实测资料建立了地温与位置、高程、坡向和太阳辐射的关系,并根据地温-下限关系估算了该区多年冻土下限深度的分布情况.研究表明,该区有多年冻土约占36.9%,季节冻土占57.5%,多年冻土主要分布在34°N~36.5°N范围的喀喇昆仑、西昆仑一带,季节冻土主要分布在塔里木盆地和34°N以南地区.阿里高原及以南是岛状多年冻土分布区域,其多年冻土分布面积少于此前出版的冻土图所绘制的.青藏高原西部区域的多年冻土下限深度整体表现为由东南-西北逐渐加深.

Permafrost distribution modeling and depth estimation in the Western Qinghai-Tibet Plateau

In this study, an extended surface frost number model (E-FROSTNUM) is applied to simulate the spatial distribution of permafrost in the study area combined with remotely sensed data and available field survey data from an ongoing project titled Permafrost Background Investigation over the Qinghai-Tibet Plateau. The distribution simulation is verified with the two typical areas investigated during the project. Moreover, a relationship between soil temperatures at a 10-m depth and topographic factors (latitude/longitude, elevation, aspect) and potential incoming solar radiation is found to be significant and applicable to estimate soil temperature at the 10-m depth in the study area. Based on this estimation, the permafrost depths are computed using a regressed relationship of 10 m soil temperature and permafrost bottom depth, derived from the west Kunlun borehole records. The study shows that 36.9% of the area is covered by permafrost and mainly distributed in the areas of Karakoram and western Kunlun Mountains in a range of 34°~36.5°N, and 57.5% covered by seasonally frozen soil, which includes the Tarim Basin and the area south of 34°N.