Water flow through sediments and at the ice-sediment interface beneath Sermeq Kujalleq (Store Glacier), Greenland

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: http://doi.org/10.1017/jog.2021.121. This is version 2 of this Preprint.


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Samuel Huckerby Doyle, Bryn Hubbard , Poul Christoffersen, Robert Law , Duncan Hewitt , Jerome Neufeld , Charlotte Schoonman , Tom Chudley , Marion Bougamont 


Subglacial hydrology modulates basal motion but remains poorly constrained, particularly for soft-bedded Greenlandic outlet glaciers. Here, we report detailed measurements of the response of subglacial water pressure to the connection and drainage of adjacent water-filled boreholes drilled through kilometre-thick ice on Sermeq Kujalleq (Store Glacier). These measurements provide evidence for gap opening at the ice-sediment interface, Darcian flow through the sediment layer, and the forcing of water pressure in hydraulically-isolated cavities by stress transfer. We observed a small pressure drop followed by a large pressure rise in response to the connection of an adjacent borehole, consistent with the propagation of a flexural wave within the ice and underlying deformable sediment. We interpret the delayed pressure rise as evidence of no pre-existing conduit and the progressive decrease in hydraulic transmissivity as the closure of a narrow (< 1.5mm) gap opened at the ice-sediment interface, and a reversion to Darcian flow through the sediment layer with a hydraulic conductivity of ≤ 10^-6 m/s . We suggest that gap opening at the ice-sediment interface deserves further attention as it will occur naturally in response to the rapid pressurisation of water at the bed.




Earth Sciences, Glaciology


Subglacial sediments, Subglacial processes, Glacial tills, Ice dynamics, Subglacial sediments, Subglacial processes, Glacial tills


Published: 2021-07-05 03:48

Last Updated: 2021-10-22 10:14

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CC BY Attribution 4.0 International

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Data will be deposited in a data repository at final publication.

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