Temporal and spatial variations of the active layer along the Qinghai-Tibet Highway in a permafrost region  

作　　者：LI Ren ZHAO Lin DING YongJian WU TongHua XIAO Yao DU ErJi LIU GuangYue QIAO YongPing 

机构地区：[1]Research Station on Cryosphere of Qinghai-Xizang(Tibet)Plateau,Lanzhou 730000,China [2]State Key Laboratory on Cryospheric Sciences,Lanzhou 730000,China [3]Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences,Lanzhou 730000,China

出　　处：《Chinese Science Bulletin》2012年第35期4609-4616,共8页

基　　金：supported by the National Natural Science Foundation of China(40871037,40830533 and 40901042);the Hundred Talents Program of the Chinese Academy of Sciences(51Y251571);the National Basic Research Program of China(2007CB411504 and 2007CB411505);Infrastructure Projects from Chinese Ministry Science and Technology(2008FY110200);the State Key Laboratory of Cryospheric Science(SKLCS-ZZ-2010-03);Background of ecological monitoring for the ecological environment protection and construction in Three-Rivers Source Nature Resource Protection Areas-Permafrost monitoring and assessment project;the Cryosphere Research Station on the Qinghai-Xizang Plateau,Chinese Academic Sciences

摘　　要：Using monitored active layer thickness(ALT) and environmental variables of 10 observation fields along the Qinghai-Tibet Highway in permafrost region of the Qinghai-Tibetan Plateau(QTP),a model for ALT estimation was developed.The temporal and spatial characteristics of the ALT were also analyzed.The results showed that in the past 30 years ALT in the study region increased at a rate of 1.33 cm a-1.Temperatures at the upper limit of permafrost and at 50 cm depth,along with soil cumulative temperature at 5 cm depth also exhibited a rising trend.Soil heat flux increased at a rate of 0.1 Wm-2 a-1.All the above changes demonstrated that the degradation of permafrost happened in the study region on the QTP.The initial thawing date of active layer was advanced,while the initial freezing date was delayed.The number of thawing days increased to a rate of 1.18 da-1.The variations of active layer were closely related to the permafrost type,altitude,underlying surface type and soil composition.The variations were more evident in cold permafrost region than in warm permafrost region,in high-altitude region than in low-altitude region,in alpine meadow region than in alpine steppe region;and in fine-grained soil region than in coarse-grained soil region.Using monitored active layer thickness（ALT） and environmental variables of 10 observation fields along the Qinghai-Tibet Highway in permafrost region of the Qinghai-Tibetan Plateau（QTP）,a model for ALT estimation was developed.The temporal and spatial characteristics of the ALT were also analyzed.The results showed that in the past 30 years ALT in the study region increased at a rate of 1.33 cm a-1.Temperatures at the upper limit of permafrost and at 50 cm depth,along with soil cumulative temperature at 5 cm depth also exhibited a rising trend.Soil heat flux increased at a rate of 0.1 Wm-2 a-1.All the above changes demonstrated that the degradation of permafrost happened in the study region on the QTP.The initial thawing date of active layer was advanced,while the initial freezing date was delayed.The number of thawing days increased to a rate of 1.18 da-1.The variations of active layer were closely related to the permafrost type,altitude,underlying surface type and soil composition.The variations were more evident in cold permafrost region than in warm permafrost region,in high-altitude region than in low-altitude region,in alpine meadow region than in alpine steppe region;and in fine-grained soil region than in coarse-grained soil region.

关 键 词：多年冻土区 青藏公路 空间变化 时间 活性层 多年冻土地区 高寒草甸地区 活动层厚度 

分 类 号：U412.221[交通运输工程—道路与铁道工程]