TY - CONF
T1 - Hydro-mechanical regulation of ice flow on Sermeq Kujalleq (Store Glacier), West Greenland
AU - Doyle, Samuel
AU - Hubbard, Bryn
AU - Christoffersen, Poul
AU - Law, Robert
AU - Chudley, Thomas
AU - Hewitt, Duncan
AU - Neufeld, Jerome
AU - Schoonman, Charlotte M.
AU - Bougamont, Marion
PY - 2021/12/1
Y1 - 2021/12/1
N2 - Our knowledge of the relationship between subglacial hydrology and basal
motion remains incomplete, particularly for fast-moving and soft-bedded
outlet glaciers. To address this, we drilled and instrumented three
boreholes to the bed at locations extending away from a suspected
subglacial channel at a site 30 km from the terminus of Sermeq Kujalleq
(Store Glacier), Greenland. We present detailed results from the
analysis of borehole response tests and time series of subglacial water
pressure, surface ice motion, surface melt, and supraglacial river
discharge. These data reveal that the boreholes connected to both
hydraulically-isolated and weakly-connected components of the subglacial
drainage system. Measurements of the response of subglacial water
pressure to the connection and drainage of adjacent water-filled
boreholes provide evidence for gap opening at the ice-sediment
interface, Darcian flow through the sediment layer, and the forcing of
water pressure in a hydraulically-isolated cavity by elastic 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 through the ice and underlying
deformable sediment. We interpret the delayed pressure rise as evidence
of no pre-existing conduit and the subsequent progressive decrease in
hydraulic transmissivity as the closure of a narrow (
AB - Our knowledge of the relationship between subglacial hydrology and basal
motion remains incomplete, particularly for fast-moving and soft-bedded
outlet glaciers. To address this, we drilled and instrumented three
boreholes to the bed at locations extending away from a suspected
subglacial channel at a site 30 km from the terminus of Sermeq Kujalleq
(Store Glacier), Greenland. We present detailed results from the
analysis of borehole response tests and time series of subglacial water
pressure, surface ice motion, surface melt, and supraglacial river
discharge. These data reveal that the boreholes connected to both
hydraulically-isolated and weakly-connected components of the subglacial
drainage system. Measurements of the response of subglacial water
pressure to the connection and drainage of adjacent water-filled
boreholes provide evidence for gap opening at the ice-sediment
interface, Darcian flow through the sediment layer, and the forcing of
water pressure in a hydraulically-isolated cavity by elastic 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 through the ice and underlying
deformable sediment. We interpret the delayed pressure rise as evidence
of no pre-existing conduit and the subsequent progressive decrease in
hydraulic transmissivity as the closure of a narrow (
M3 - Paper
ER -