| The Sichuan-Tibet route in this study denotes the combined name of the Sichuan-Tibet Highway and the Sichuan-Tibet Railway.The Sichuan-Tibet route is one of the main trunk routes in the southwest region,assuming a pivotal role in linking the central and western regions,and has an important role and significance economically,militarily,and culturally.The Sichuan-Tibet Line is the most treacherous section in China,located in the Qinghai-Tibet Plateau region,crossing the Transverse Range,with very dense glaciers and glacial lakes along the line,threatening the safe operation of the route.The main contents of this paper are the cataloguing and changes of glaciers and glacial lakes,the extraction of glacier surface flow velocities and the analysis of movement conditions,and the evaluation of the danger of glaciers and glacial lakes with potential threats to the Sichuan-Tibet route.In this paper,the 2017 glacier cataloguing dataset,1990 and 2018 glacial lake cataloguing datasets within the 100 km buffer zone of the Sichuan-Tibet line were extracted based on the second glacier cataloguing data,Landsat TM/TM+/OLI images,and SRTM DEM data using NDWI and manual visual interpretation;the glacier surface motion characteristics were analyzed based on the 2017 glacier cataloguing data of the Sichuan-Tibet line and Sentinel-1A data,the surface flow velocity of glaciers was extracted based on the SAR image feature matching method,and the surface motion characteristics of glaciers in the Sichuan-Tibet Line area were analyzed.The study found that:(1)In 2017,there were 14,520 glaciers in the Sichuan-Tibet line area,with a total area of8,352.63±9.25 km~2.Glaciers in general showed an obvious trend of area retreat,with an area retreat rate of-2.89%a-1,but there were differences in the area distribution and changes in each altitude,slope and slope direction within different watersheds.(2)In 2018,there were 6340 glacial lakes with a total area of 439.26±1.04 km~2 in the Sichuan-Tibet route area,and the overall change over 28 years was characterized by"increasing number and area expansion",with an area expansion rate of 0.37%a-1,but the area distribution and area distribution of each elevation,size and type within different mountain ranges variability in change.(3)The glacier surface flow velocity in the Sichuan-Tibet line area was in an overall increasing trend from January 2017 to December 2020,and the average glacier surface flow velocity increased from 0.1920 m d-1 to 0.2142 m d-1 in 2017,and the average glacier surface flow velocity in the study area was 0.2027 m d-1 in 4 years.(4)By analyzing the glacier surface flow velocity and its watershed information,we initially identified potentially dangerous glaciers and evaluated the potential threat of glaciers to the Sichuan-Tibet line in a graded manner based on their slope and the distance between the end of the glacier and the Sichuan-Tibet line,and obtained information on nine glaciers with high potential leaping danger.(5)Preliminary identification of glacial lakes with potential risk of collapse in the Sichuan-Tibet line area by parameters such as glacial lake size,area expansion rate and distance from the end of the parent glacier,and hierarchical evaluation of the threat to the Sichuan-Tibet line based on the distance between the glacial lake and the line,collated information on four glacial lakes with high potential risk of collapse.The content of this study provides data support and theoretical basis for the disaster caused by glacial jump and glacial lake outburst in the Sichuan-Tibet route area. |
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