Abstract
Abstract. We use the Shreve hydraulic potential equation as a simplified approach to investigate potential subglacial lake locations and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets. We validate the method by demonstrating its ability to recall the locations of >60% of the known subglacial lakes beneath the Antarctic Ice Sheet. This is despite uncertainty in the ice-sheet bed elevation and our simplified modelling approach. However, we predict many more lakes than are observed. Hence we suggest that thousands of subglacial lakes remain to be found. Applying our technique to the Greenland Ice Sheet, where very few subglacial lakes have so far been observed, recalls 1607 potential lake locations, covering 1.2% of the bed. Our results will therefore provide suitable targets for geophysical surveys aimed at identifying lakes beneath Greenland. We also apply the technique to modelled past ice-sheet configurations and find that during deglaciation both ice sheets likely had more subglacial lakes at their beds. These lakes, inherited from past ice-sheet configurations, would not form under current surface conditions, but are able to persist, suggesting a retreating ice-sheet will have many more subglacial lakes than advancing ones. We also investigate subglacial drainage pathways of the present-day and former Greenland and Antarctic ice sheets. Key sectors of the ice sheets, such as the Siple Coast (Antarctica) and NE Greenland Ice Stream system, are suggested to have been susceptible to subglacial drainage switching. We discuss how our results impact our understanding of meltwater drainage, basal lubrication and ice-stream formation.
Highlights
Understanding the drainage of meltwater beneath ice is fundamental to resolving ice-flow dynamics because water pressure influences both the strength of the subglacial sediment and the frictional interaction between ice and its sole (Clarke, 2005; Schoof, 2010)
Given the high percentage of known subglacial lakes recalled beneath the Antarctic Ice Sheet (AIS) (Sect. 3) we suggest that simple hydrological calculations can be a useful tool for simulating subglacial lakes and drainage pathways beneath otherice sheets
The incorporation of the subglacial lake-surface reflector in the bed topography and thickness grids could be considered a fatal flaw in using hydraulic potential equations to identify subglacial lake locations
Summary
Understanding the drainage of meltwater beneath ice is fundamental to resolving ice-flow dynamics because water pressure influences both the strength of the subglacial sediment and the frictional interaction between ice and its sole (Clarke, 2005; Schoof, 2010). Röthlisberger, 1972; Walder and Hallet, 1979; Nienow et al, 1998); (ii) distributed networks of passageways and cavities Subglacial lakes beneath the AIS are known to comprise a crucial component of the subglacial environment, capable of actively interacting with the surrounding hydrological network and transmitting large volumes of meltwater between lakes and towards the grounding line (e.g. Wingham et al, 2006; Fricker et al, 2007; Smith et al, 2009).
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