EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Neoglacial increase in high-magnitude Glacial Lake Outburst Flood frequency (Baker River, Patagonia, 47°S)

Sebastien Bertrand1, Elke Vandekerkhove1, Dmitri Mauquoy2, Dave McWethy3, Brian Reid4, Sarah Stammen1, Krystyna Saunders5, and Fernando Torrejon6
Sebastien Bertrand et al.
  • 1Renard Center of Marine Geology, Ghent University, Gent, Belgium (
  • 2School of Geosciences, University of Aberdeen, Aberdeen, United Kingdom
  • 3Department of Earth Sciences, Montana State University, Bozeman, USA
  • 4Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique, Chile
  • 5Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
  • 6Centro EULA, Universidad de Concepción, Concepción, Chile

Glacial Lake Outburst Floods (GLOFs) constitute a major hazard in periglacial environments. Despite a recent increase in the size and number of glacial lakes worldwide, there is only limited evidence that climate change is affecting GLOF frequency. In Patagonia, GLOFs are particularly common in the Baker River watershed (47°S), where 21 GLOFs occurred between 2008 and 2017 due to the drainage of Cachet 2 Lake into the Colonia River, a tributary of the Baker River. During these GLOFs, the increased discharge from the Colonia River blocks the regular flow of the Baker River, resulting in the inundation of the Valle Grande floodplain, which is located approximately 4 km upstream of the confluence. To assess the possible long-term relationship between GLOF frequency, glacier behavior, and climate variability, four sediment cores collected in the Valle Grande floodplain were analyzed. Their geophysical and sedimentological properties were examined, and radiocarbon-based age-depth models were constructed. All cores consist of dense, fine-grained, organic-poor material alternating with low-density organic-rich deposits. The percentage of lithogenic particles, which were most likely deposited during high-magnitude GLOFs, was used to reconstruct the flood history of the last 2.75 kyr. Results show increased flood activity between 2.57 and 2.17 cal kyr BP, and between 0.75 and 0 cal kyr BP. These two periods coincide with glacier advances during the Neoglaciation. Our results suggest that GLOFs are not a new phenomenon in the region. Although rapid glacier retreat is likely responsible for high GLOF frequency in the 21st century, high-magnitude GLOFs seem to occur more frequently when glaciers are larger and thicker.

How to cite: Bertrand, S., Vandekerkhove, E., Mauquoy, D., McWethy, D., Reid, B., Stammen, S., Saunders, K., and Torrejon, F.: Neoglacial increase in high-magnitude Glacial Lake Outburst Flood frequency (Baker River, Patagonia, 47°S), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14687,, 2021.

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