祁连山中东部的冻土特征(Ⅰ):多年冻土分布

祁连山地区地势高耸,气候严寒,冰缘现象广布,各类冰缘现象受地形与水分条件的控制,分布具有明显的规律性.祁连山多年冻土属青藏冻土区,阿尔金山-祁连山亚区,分布在海拔3400 m以上的高山、谷地、盆地中.多年冻土分布具有明显的高度地带性,随高度增加,冻土分布呈现出季节冻土-岛状冻土-连续冻土更替,同时,多年冻土下界高程与经度明显相关,自西向东表现出下降趋势,下降率约为每经度150 m,这一变化与降水在东西方向的变化有关.山区微气候因素复杂多变,也造成了冻土分布的复杂性,局地因素对冻土分布影响显著,对比分析了坡向,植被与水分、岩性,季节性积雪等诸因素对多年冻土分布的影响.

Permafrost in the Middle-East Section of Qilian Mountains(I):Distribution of permafrost

Climate is very cold in the Qilian Mountains because of higher altitude.There are periglacial phenomenon widespread that is controlled by topographical and hydrological conditions.The permafrost in Qilian Mountains is subjected to the sub-permafrost area of Altun Mountains-Qilian Mountains of the Tibetan Plateau permafrost area with a lower limit about 3 400 m.The distribution characteristics of permafrost in this area were described based on drilling investigation.With the increase of altitude,the seasonally frozen ground zone is subrogated by patchy permafrost zone and then by continuous permafrost zone.Lower limit of permafrost descends from west to east,dependent on latitude and precipitation.Distribution of permafrost also depends on slope orientation,seasonally snow cover distribution and vegetation distribution.