疏勒河流域地处祁连山西段,气候极端干旱。2008年6月在疏勒河源区海拔3729~3890m的不同地面、地形条件下在5个点上布设了10眼钻孔进行钻探勘察,并布设测温管定期监测地温。根据勘察和测温资料,确定了疏勒河流域内多年冻土下界高程在3750m左右,查明河谷中松散地层以冲积层为主,多为粗颗粒土,多年冻土含冰量普遍较低。局地因素对多年冻土状态影响明显。其中坡度差异可以使地温相差0.5℃,坡向的差异可以使地温相差达1.0℃;地层水分含量对浅层地温的影响甚至超过坡向的影响;地面状态的差异,造成地温、活动层厚度等方面的显著差异。与祁连山中东部地区相比,疏勒河源区多年冻土几乎没有生态过程的影响,多年冻土形成和保存受气候驱动,基本上代表了一类干旱气候条件下的多年冻土特征。
The Shlehe River Basin is located in the western part of the Qilian Mountains, where climate is very dry. Ten boreholes were drilled at 5 sites on various types of land surface and terrain in the source areas of the Shule River valley for monitoring permafrost, and measured temperature tubes were assembled in the boreholes. According to records of borehole and measured temperature, the elevation of permafrost lower limit was determined to be 3750 m (a.s.l.) and volume of ground ice was little because loose stratum is alluvium composed of coarse soil. The permafrost state was affected by local factors obviously. Discrepancy of a slope gradient can lead to a ground temperature difference of 0.5 ℃, while discrepancy of slope aspect can result in a ground temperature difference of 1.0 ℃. Influences of soil water content on ground temperature of shallow layers are even greater than those of slope aspect. Discrepancy of ground condition can result in significant difference in ground temperature and depth of active layer. Contrast to permafrost of central-eastern Qilian Mountains, permafrost in the Shule River source areas is not affected by ecological processes and its formation and preservation were directly driven by climate. So the permafrost of the Shule River source areas was typical of that of arid regions.