Glacial and geomorphic effects of a supraglacial lake drainage and outburst event, Everest region, Nepal Himalaya
Glacial and geomorphic effects of a supraglacial lake drainage and outburst event, Everest region, Nepal Himalaya
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DOI：
10.5194/tc-12-3891-2018
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
Evan S. Miles
中科院分区：
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作者：
Evan S. Miles
抽象的。2017年4月至7月，尼泊尔珠峰地区昌日沙尔冰川上的一组冰上池塘迅速填满，汇合成一个180000平方米的∼湖，然后突然完全通过昌日沙尔冰川和昆布冰川排水(7月15日至17日)。我们使用PlanetScope和Pléiade卫星正射成像来记录该系统在其非常短的充填期内的演变，并评估暴发洪水对冰川和冰川的影响。我们还使用高分辨率立体数字高程模型(DEM)来完成对该事件的冰川和地貌影响的详细分析。最后，我们使用下游4公里处流量计的流量记录来完善我们对这次暴发的年表和震级的解释。我们推断，很大程度上是通过位于其流动路径上的两个冰川进行地下排水，并通过昆布冰川下部进行有效的排水。1.36±0.19×106立方米蓄水的排放和随后的暴发对冰川和冰川地形产生了明显的地貌影响，包括沿着昌日努普冰川小溪的深切割和山体滑坡，昆布末端附近的浅冰道坍塌，以及昆布冰川下游至少11公里处的广泛、加强的河岸侵蚀。这些突如其来的变化摧毁了三个地点的主要小径，表明了短暂、相对较小的冰川湖泊构成的潜在危险。
Abstract. A set of supraglacial ponds filled rapidly between April and July 2017 on Changri Shar Glacier in the Everest region of Nepal, coalescing into a ∼180 000 m2 lake before sudden and complete drainage through Changri Shar and Khumbu glaciers (15–17 July). We use PlanetScope and Pléiades satellite orthoimagery to document the system's evolution over its very short filling period and to assess the glacial and proglacial effects of the outburst flood. We also use high-resolution stereo digital elevation models (DEMs) to complete a detailed analysis of the event's glacial and geomorphic effects. Finally, we use discharge records at a stream gauge 4 km downstream to refine our interpretation of the chronology and magnitude of the outburst. We infer largely subsurface drainage through both of the glaciers located on its flow path, and efficient drainage through the lower portion of Khumbu Glacier. The drainage and subsequent outburst of 1.36±0.19×106 m3 of impounded water had a clear geomorphic impact on glacial and proglacial topography, including deep incision and landsliding along the Changri Nup proglacial stream, the collapse of shallow englacial conduits near the Khumbu terminus and extensive, enhanced bank erosion at least as far as 11 km downstream below Khumbu Glacier. These sudden changes destroyed major trails in three locations, demonstrating the potential hazard that short-lived, relatively small glacial lakes pose.