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The drainage of glacier and ice sheet surface lakes

Christian Schoof Orcid Logo, Sue Cook Orcid Logo, Bernd Kulessa Orcid Logo, Sarah Thompson Orcid Logo

Journal of Fluid Mechanics, Volume: 961

Swansea University Author: Bernd Kulessa Orcid Logo

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DOI (Published version): 10.1017/jfm.2023.130

Abstract

Supraglacial lakes play a central role in storing melt water, enhancing surface melt, and ultimately in driving ice flow and ice shelf melt through injecting water into the subglacial environment and facilitating fracturing. Here, we develop a model for the drainage of supraglacial lakes through the...

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Published in: Journal of Fluid Mechanics
ISSN: 0022-1120 1469-7645
Published: Cambridge University Press (CUP) 2023
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URI: https://cronfa.swan.ac.uk/Record/cronfa62752
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Abstract: Supraglacial lakes play a central role in storing melt water, enhancing surface melt, and ultimately in driving ice flow and ice shelf melt through injecting water into the subglacial environment and facilitating fracturing. Here, we develop a model for the drainage of supraglacial lakes through the dissipation-driven incision of a surface channel. The model consists of the St Venant equations for flow in the channel, fed by an upstream lake reservoir, coupled with an equation for the evolution of channel elevation due to advection, uplift, and downward melting. After reduction to a ‘stream power’-type hyperbolic model, we show that lake drainage occurs above a critical rate of water supply to the lake due to the backward migration of a shock that incises the lake seal. The critical water supply rate depends on advection velocity and uplift (or more precisely, drawdown downstream of the lake) as well as model parameters such as channel wall roughness and the parameters defining the relationship between channel cross-section and wetted perimeter. Once lake drainage does occur, it can either continue until the lake is empty, or terminate early, leading to oscillatory cycles of lake filling and draining, with the latter favoured by large lake volumes and relatively small water supply rates.
College: Faculty of Science and Engineering
Funders: CGS was supported by Natural Sciences and Engineering Council of Canada Discovery Grant RGPIN-2018-04665. SC and ST received support from the Australian Government as part of the Antarctic Science Collaboration Initiative program.