Surge dynamics and lake outbursts of Kyagar Glacier, Karakoram
Surge dynamics and lake outbursts of Kyagar Glacier, Karakoram
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DOI：
10.5194/tc-11-723-2017
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发表时间：
2016-11
期刊：
影响因子：
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通讯作者：
Vanessa Round;S. Leinss;M. Huss;C. Haemmig;I. Hajnsek
中科院分区：
文献类型：
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作者：
Vanessa Round;S. Leinss;M. Huss;C. Haemmig;I. Hajnsek
抽象的。中国喀喇昆仑山的基雅加尔冰川最近的激增周期导致冰坝湖的形成，随后在2015年和2016年导致冰川湖溃决洪水（GLOF）超过4000万立方米。Kyagar冰川的GLOF在2002年及更早的时候达到了这个尺寸的两倍，但是冰川涌动在GLOF形成中的作用以前没有被认识到。我们对2011年至2016年的冰川浪涌动态进行了综合分析，评估了浪涌机制并评估了浪涌周期对GLOFs的影响。根据TanDEM-X（TerraSAR-X数字高程测量附件）、Sentinel-1A和Landsat卫星数据创建了80多个冰川表面速度场。TanDEM-X高程模型的时间序列揭示了冰厚分布的变化。分析表明，在持续至少14年的平静阶段，冰块建立在冰舌顶部的水库区域，和终端变薄了100米，但在2年前的浪涌开始这种模式逆转。浪涌开始与2014年融化季节的开始，并在随后的15个月的速度演变的方式与水文控制浪涌机制一致。剧烈的加速与融化季节相吻合，冬季减速伴随着冰下排水，2015年GLOF之后发生了快速的浪涌终止。在激增的快速基础运动似乎是由高水压控制，造成输入的地表水到一个低效的冰下排水系统或不稳定的冰下冰碛。到2016年底，潜在的湖泊体积增加到7000多万立方米，这是由于终点站增厚了60多米。应通过遥感仔细监测湖泊的形成和冰坝高度的演变，以预测不久的将来会出现大的全球冰川融化。
Abstract. The recent surge cycle of Kyagar Glacier, in the Chinese Karakoram, caused formation of an ice-dammed lake and subsequent glacial lake outburst floods (GLOFs) exceeding 40 million m3 in 2015 and 2016. GLOFs from Kyagar Glacier reached double this size in 2002 and earlier, but the role of glacier surging in GLOF formation was previously unrecognised. We present an integrative analysis of the glacier surge dynamics from 2011 to 2016, assessing surge mechanisms and evaluating the surge cycle impact on GLOFs. Over 80 glacier surface velocity fields were created from TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement), Sentinel-1A, and Landsat satellite data. Changes in ice thickness distribution were revealed by a time series of TanDEM-X elevation models. The analysis shows that, during a quiescence phase lasting at least 14 years, ice mass built up in a reservoir area at the top of the glacier tongue, and the terminus thinned by up to 100 m, but in the 2 years preceding the surge onset this pattern reversed. The surge initiated with the onset of the 2014 melt season, and in the following 15 months velocity evolved in a manner consistent with a hydrologically controlled surge mechanism. Dramatic accelerations coincided with melt seasons, winter deceleration was accompanied by subglacial drainage, and rapid surge termination occurred following the 2015 GLOF. Rapid basal motion during the surge is seemingly controlled by high water pressure, caused by input of surface water into either an inefficient subglacial drainage system or unstable subglacial till. The potential lake volume increased to more than 70 million m3 by late 2016, as a result of over 60 m of thickening at the terminus. Lake formation and the evolution of the ice dam height should be carefully monitored through remote sensing to anticipate large GLOFs in the near future.