1. Water flow through sediments and at the ice-sediment interface beneath Sermeq Kujalleq (Store Glacier), Greenland.
- Author
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Doyle, Samuel H., Hubbard, Bryn, Christoffersen, Poul, Law, Robert, Hewitt, Duncan R., Neufeld, Jerome A., Schoonman, Charlotte M., Chudley, Thomas R., and Bougamont, Marion
- Subjects
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SUBGLACIAL lakes , *GLACIERS , *SEDIMENTS , *WATER pressure , *PRESSURE drop (Fluid dynamics) , *THEORY of wave motion , *FLEXURAL vibrations (Mechanics) - Abstract
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 (< 1.5 mm) 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−1. 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. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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