中巴公路沿线冰川运动特征

Characteristic of Glaciers' Movement Along Karakoram Highway

中巴公路作为一条国际公路,对中国以及巴基斯坦等南亚、西亚国家有着非常重要的意义。公路穿越了帕米尔高原和喀喇昆仑山脉这个山岳冰川分布十分密集的地区,沿线的冰川前进时常威胁着公路的安全运营。利用2016年1月至2017年6月间的81景Sentinel-1合成孔径雷达影像,采用特征匹配的方法获得了1 a多来中巴公路沿线冰川的运动速度,并对比1993年和2006年的流速,对冰川前进的可能性进行分析。中巴公路沿线冰川以新疆塔吉克自治县和巴基斯坦北部城市库达巴德为界可分为北中南3部分,研究发现:北部地区冰川表面流速较为稳定,对公路安全运营的威胁很小;中部地区冰川规模普遍较小,且距离公路较远;而南部地区的大规模冰川流速较快,部分冰川积累区表面流速高达2 md^(-1)以上。为此,在南部地区选取了距离公路较近的巴托拉等4条冰川进行详细分析,结果显示帕苏冰川为1条快速运动冰川,存在冰川末端前进的可能性,巴托拉冰川、固尔金冰川和吉尔密特冰川冰舌上部流速较快,具有较强的活动特性。

As an international highway,the Karakoram Highway(KKH)is of great importance to China,Pakistan,South-Asian and West-Asian Countries.It crosses the Karakoram Mountains,one of the most glaciers concentrated regions,and is being threatened from glaciers along KKH all the time.Currently,Synthetic Aperture Radar(SAR)have been proved reliably profitable on analyst glaciers’movement.In this study,we analyzed the characteristics of glaciers’movement along KKH by using feature-tracking method based on 81 scenes of Sentinel-1 A data obtained between Jan.2016 to Jun.2017.And ERS-1 data in 1993 and ALOS PALSAR data in 2006 are taken as comparison for analyzing the trend of glacial surface flow rate.Our results indicated that the glacier flow streamline is basically consistent with the geometric center line of the ice tongue and the velocities increase away from both margins;summer motion was higher than winter motion.The glaciers along the KKH can be divided into three parts:north,central and south,based the boundaries of Tajik Autonomous County in Sinkiang and Khuda Abad,the northern city of Pakistan.The glacier surface velocities of the trunk is lower than 0.15 md^-1 and relatively stable in the northern.The scale of glaciers in the central region is generally small and far from the KKH.The glaciers in north and central regions may not affect the operation of highways.While parts of the large scale glaciers in the south region had higher velocities,particularly along the section of the highway near Batura Sar.Here,4 glaciers were selected to analyze in detail which are closest to the KKH include Batura,Pasu,Ghulkin and Gulmit in the south region.Seen from all results,the Pasu glacier has rapid motion during the study period,the normal velocity of its trunk is between 1 and 1.5 md^-1,and can reach 3 md^-1 in special place.All these 4 glaciers were flowing faster than other glaciers which reflect the high quantitative mass balance.Accordingly,the safety operation and residents’life along the Batura Sar may be threatened by these four glaciers advance.