川西藏东地区冰湖主要成因类型与分布规律

Genetic types and distribution of glacial lakes in western Sichuan and eastern Tibet

全球气候变暖背景下,川西藏东地区冰湖库容增加且溃决事件频发,持续威胁着基础设施建设和区域经济发展,因此区内冰湖的分布规律及特征急需探明。聚焦川西藏东地区重大工程建设,通过目视遥感解译结合冰蚀湖、冰碛湖、槽谷湖3种主要成因类型冰湖,从成因类型角度分析探讨了研究区2010—2020年内冰湖空间分布特征及规律。结果显示:研究区面积大于50 m^(2)的冰湖共计17737个,其中冰蚀湖11903个,冰碛湖5734个,槽谷湖100个,总面积达7.93×10^(3) km^(2);行政区划上西藏林芝察隅县分布冰湖数量最多(2161个),占比12.18%;山系和流域中分布冰湖数量最多者分别为沙鲁里山脉(5161个,占比29.10%)和雅鲁藏布流域(5450个,占比30.73%);冰蚀湖与冰碛湖空间分布规律大致相同,集中于4500~5000 m高程范围内(占比50.57%),处于冰川活跃区;而槽谷湖分布海拔较低,且与后缘冰川作用较小,主要集中分布在4000~5000 m高程之间(占其总数的77.00%)。综合不同成因类型的冰湖特征及其与冰川相互关系,梳理出潜在危险冰湖9个,其中冰碛湖7个,槽谷湖2个。未来面向区内重大铁路、公路、水电站等工程建设运营,需重点关注冰湖风险并开展针对性详细调查、评估和监测预警。

Global warming has caused dramatic glacial lake expansions and increasing of glacial lake outburst floods(GLOFs) in western Sichuan and eastern Tibet(WSET),indicating that the spatial distribution of glacial lakes in this region need to be ascertained imminently.The overall distribution of glacial lakes of WSET during 2010—2020 has been mapped on the basis of different genetic types by manual visual interpretation method,which mainly involves glacial erosion lakes(GELs),moraine lakes(MLs),and barrier lakes(BLs).The results show that there are total 17737 glacial lakes inventoried in WSET with each area of greater than 50 m^(2),including 11903 GELs,5734 MLs and 100 BLs,covering a total area of 7.93×10^(3) km^(2).Zayü County in Nyinchi,Tibet,as the most densely distributed county of glacial lakes,hosts 2161 glacial lakes,which account for 12.18% of the total number.Additionally,the glacial lakes in Shaluli Mountains and Yarlung Zangbo River basin are the most lake-concentrated ones,accounting for 29.10%(5161 lakes) and 30.73%(5450 lakes) of the total respectively.Meanwhile,GELs and MLs share the similar spatial distribution patterns,and are mostly concentrated at an altitude of 4500~5000 m(50.57% of the total),implying a glacier active area.Most of BLs(77% of the total BLs) are located at the altitude of 4000~5000 m,indicating a negative interaction with the glaciers.Combined with the comprehensive analysis of genetic types of glacial lakes and their relationships with the glaciers,9 potential dangerous glacial lakes,including 7 MLs and 2 BLs,are preliminarily identified.Regarding the risk of GLOFs in the future,the focus researches,such as investigations,assessments,monitoring,and early warning,should be carried out in the construction and operation of the major infrastructures in WSET.