The 2015 Chileno Valley glacial lake outburstflood, Patagonia

Ryan Wilson, Stephan Harrison, John Reynolds, Alun Hubbard, Neil F. Glasser, Olaf Wündrich, Pablo Iribarren Anacona, Luca Mao, Sarah Shannon

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

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 × 10 6 m 3 of 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 m 3 of material was eroded from the flood-affected area whilst over 0.5 million m 3 of 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.

Original languageEnglish
Pages (from-to)51-65
Number of pages15
JournalGeomorphology
Volume332
Early online date8 Feb 2019
DOIs
Publication statusPublished - 1 May 2019

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glacial lake
outburst
valley
lake
debris flow
glacier
sediment
Little Ice Age
alluvial plain
mountain region
moraine
gully
hazard assessment
hydrograph
Postglacial
global warming
outflow
human activity

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Wilson, R., Harrison, S., Reynolds, J., Hubbard, A., Glasser, N. F., Wündrich, O., ... Shannon, S. (2019). The 2015 Chileno Valley glacial lake outburstflood, Patagonia. Geomorphology, 332, 51-65. https://doi.org/10.1016/j.geomorph.2019.01.015
Wilson, Ryan ; Harrison, Stephan ; Reynolds, John ; Hubbard, Alun ; Glasser, Neil F. ; Wündrich, Olaf ; Anacona, Pablo Iribarren ; Mao, Luca ; Shannon, Sarah. / The 2015 Chileno Valley glacial lake outburstflood, Patagonia. In: Geomorphology. 2019 ; Vol. 332. pp. 51-65.
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Wilson, R, Harrison, S, Reynolds, J, Hubbard, A, Glasser, NF, Wündrich, O, Anacona, PI, Mao, L & Shannon, S 2019, 'The 2015 Chileno Valley glacial lake outburstflood, Patagonia', Geomorphology, vol. 332, pp. 51-65. https://doi.org/10.1016/j.geomorph.2019.01.015

The 2015 Chileno Valley glacial lake outburstflood, Patagonia. / Wilson, Ryan; Harrison, Stephan; Reynolds, John; Hubbard, Alun; Glasser, Neil F.; Wündrich, Olaf; Anacona, Pablo Iribarren; Mao, Luca; Shannon, Sarah.

In: Geomorphology, Vol. 332, 01.05.2019, p. 51-65.

Research output: Contribution to journalArticle

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Wilson R, Harrison S, Reynolds J, Hubbard A, Glasser NF, Wündrich O et al. The 2015 Chileno Valley glacial lake outburstflood, Patagonia. Geomorphology. 2019 May 1;332:51-65. https://doi.org/10.1016/j.geomorph.2019.01.015