The 2015 Chileno Valley glacial lake outburst flood, Patagonia
The 2015 Chileno Valley glacial lake outburst flood, Patagonia
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DOI：
10.1016/j.geomorph.2019.01.015
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发表时间：
2019-05
期刊：
影响因子：
3.9
通讯作者：
R. Wilson;S. Harrison;J. Reynolds;A. Hubbard;N. Glasser;Olaf Wündrich;P. I. Anacona;L. Mao;S. Shannon
中科院分区：
文献类型：
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作者：
R. Wilson;S. Harrison;J. Reynolds;A. Hubbard;N. Glasser;Olaf Wündrich;P. I. Anacona;L. Mao;S. Shannon
在过去的世纪里，冰川湖爆发洪水（GLOFs）越来越常见，以应对气候变化，给许多山区的人类活动带来风险。在本文中，我们记录并重建了2015年12月在巴塔哥尼亚的Chileno山谷发生的大型GLOF的事件和影响的顺序。水文数据显示，洪水持续了约8天，估计总流量为105.6 × 106m3。事件的顺序如下：（1）一个大的泥石流进入湖泊从两个陡峭的，基本上没有植被的山区冲沟位于东北部的奇莱诺冰川终点。(2)泥石流造成的湖水位移增加了智利湖外流的流量。(3)湖泊和冰碛沉积物被洪水侵蚀了。(4)被侵蚀的沉积物重新分配下游的GLOF。湖出口处的GLOF后河道在某些地方加宽了130 m以上，地形的表面高程最大降低了38.8 ± 1.5 m。在更远的下游，大量夹带的沉积物沉积在冲积平原的顶部，这些沉积物形成了一个约340 m宽的扇，与GLOF前表面相比，表面高程平均增加4.6 ± 1.5 m。我们估计，约350万m3的物质从受洪水影响的地区被侵蚀，而超过50万m3的物质沉积在下游的GLOF风扇。引发GLOF的大型泥石流可能是冰川从小冰期极限退缩的副冰川反应。我们认为，GLOFs将继续发生在这些设置在未来的冰川进一步消退，以应对全球变暖，并产生潜在的不稳定湖泊。目前，巴塔哥尼亚对GLOF事件的详细研究有限，因此，这里提供的信息将有助于为该地区未来的冰川灾害评估提供信息。
Glacial Lake Outburst Floods (GLOFs) have become increasingly common over the past century in response to climate change, posing risks for human activities in many mountain regions. In this paper we document and reconstruct the sequence of events and impact of a large GLOF that took place in December 2015 in the Chileno Valley, Patagonia. Hydrograph data suggests that the flood continued for around eight days with an estimated total discharge of 105.6 × 106m3of water. The sequence of events was as follows: (1) A large debris flow entered the lake from two steep and largely non-vegetated mountain gullies located northeast of the Chileno Glacier terminus. (2) Water displaced in the lake by the debris flow increased the discharge through the Chileno Lake outflow. (3) Lake and moraine sediments were eroded by the flood. (4) Eroded sediments were redistributed downstream by the GLOF. The post-GLOF channel at the lake outlet widened in some places by >130 m and the surface elevation of the terrain lowered by a maximum of 38.8 ± 1.5 m. Farther downstream, large amounts of entrained sediment were deposited at the head of an alluvial plain and these sediments produced an ~340 m wide fan with an average increase in surface elevation over the pre-GLOF surface of 4.6 ± 1.5 m. We estimate that around 3.5 million m3of material was eroded from the flood-affected area whilst over 0.5 million m3of material was deposited in the downstream GLOF fan. The large debris flow that triggered the GLOF was probably a paraglacial response to glacier recession from its Little Ice Age limits. We suggest that GLOFs will continue to occur in these settings in the future as glaciers further recede in response to global warming and produce potentially unstable lakes. Detailed studies of GLOF events are currently limited in Patagonia and the information presented here will therefore help to inform future glacial hazard assessments in this region.