Using transient electromagnetic method to sound permafrost depth in the West Kunlun Mountains

Based on the Project of Permafrost Investigation in the Tibetan Plateau,permafrost base was sounded by using transient electromagnetic method( TEM),in typical areas of west Kunlun Mountains. It is found that using TEMto obtain the permafrost base is effective in frozen loose sediments. In the study area,distribution of permafrost is significantly characterized by spatial differential due to different in regional climate and geological conditions. The average depth of permafrost is approximately 55 m in alpine valley areas and 58 m in lowmountains and hilly areas according to TEMsound. The permafrost depth widely reaches above 60 m in Tianshuihai basin. In the heartland of the basin( near modern lake),the maximum average depth of approximately 110 m was sounded by TEM. The depth of permafrost linearly increases with decreasing ground temperature. It is estimated that the permafrost depth will increase 29 m as ground temperature at 10 m deep decreasing 1 ℃. In general,permafrost depth increases with altitude. However,local factors have an important impact on the development and distribution of permafrost sometimes. Further research on the impact mechanisms of local factors is necessary for improving the survey accuracy.