Investigation on Permafrost Distribution over the Upper Reaches of the Heihe River in the Qilian Mountains
Permafrost and seasonally frozen ground have a dramatic influence on surface hydrological processes, ecosystems, carbon cycle, and infrastructures in cold regions. The upper reaches of the Heihe River are located in the eastern part of the Qilian Mountains, where climate is cold and semi-arid. The study of permafrost distribution in Heihe River basin is of great importance for systematically understanding the regional eco-hydro-logical process, climate and environmental changes, water resources assessment and construction, etc. Field investigation on distribution of permafrost had been conducted over the upper reaches of the river during the summer of 2011. Seven boreholes ranging from 20 to 100 m in depths were drilled in early August, 2011. Based on borehole drilling information and temperature profiles meas-ured at least two months after the drilling, it is found that the lower bound of permafrost is at between 3 650 m and 3 700 m a. s. 1. Depending on altitude, the active layer depth varies from 1. 6 m at 4 132 m a. s. 1. to about 4. 0 m near the lower bound of permafrost at a little above 3 650 m a. s. 1. Mean annual ground temperatures at the depth of zero annual amplitude increases from —1.7 ℃ at 4 132 m a. s. 1. to near 0.0 ℃ at the lower bound of permafrost. Permafrost depth decreases from more than 100 m at 4 132 m a. s. 1. to 0. 0 m as moving down to 3 650 ma. s. 1. At the same time, the other local factors, such as slope, aspect, soil type, soil water(ice)content, vegetation and river channel, may also have significant effect on permafrost conditions.
lower bound of permafrostactive layeraltitudemean annual ground temperatureHeihe River basin
王庆峰、张廷军、吴吉春、彭小清、钟歆玥、牟翠翠、王康、吴青柏、程国栋
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中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室,甘肃兰州 730000
兰州大学资源环境学院,甘肃兰州 730000
National Snow and Ice Data Center, University of Colorado, Boulder Colorad0 803032-0449, USA