Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard
The flow of glaciers is largely controlled by changes at the ice–bed interface, where basal slip and sediment deformation drive basal glacier motion. Determining subglacial conditions and their responses to hydraulic forcing remains challenging due to the difficulty of accessing the glacier bed. Her...
Published in: | The Cryosphere |
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ftcopernicus:oai:publications.copernicus.org:tc110528 2024-09-15T18:07:56+00:00 Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard Bouchayer, Coline Nanni, Ugo Lefeuvre, Pierre-Marie Hult, John Steffensen Schmidt, Louise Kohler, Jack Renard, François Schuler, Thomas V. 2024-06-25 application/pdf https://doi.org/10.5194/tc-18-2939-2024 https://tc.copernicus.org/articles/18/2939/2024/ eng eng doi:10.5194/tc-18-2939-2024 https://tc.copernicus.org/articles/18/2939/2024/ eISSN: 1994-0424 Text 2024 ftcopernicus https://doi.org/10.5194/tc-18-2939-2024 2024-08-28T05:24:22Z The flow of glaciers is largely controlled by changes at the ice–bed interface, where basal slip and sediment deformation drive basal glacier motion. Determining subglacial conditions and their responses to hydraulic forcing remains challenging due to the difficulty of accessing the glacier bed. Here, we monitor the interplay between surface runoff and hydro-mechanical conditions at the base of the Kongsvegen glacier in Svalbard. From July 2021 to August 2022, we measured both subglacial water pressure and till strength. Additionally, we derived median values of subglacial hydraulic gradient and radius of channelized subglacial drainage system from seismic power, recorded at the glacier surface. To characterize the variations in the subglacial conditions caused by changes in surface runoff, we investigate the variations of the following hydro-mechanical properties: measured water pressure, measured sediment ploughing forces, and derived hydraulic gradient and radius, over seasonal, multi-day, and diurnal timescales. We discuss our results in light of existing theories of subglacial hydrology and till mechanics to describe subglacial conditions. We find that during the short, low-melt-rate season in 2021, the subglacial drainage system evolved at equilibrium with runoff, increasing its capacity as the melt season progressed. In contrast, during the long and high-melt-rate season in 2022, the subglacial drainage system evolved transiently to respond to the abrupt and large water supply. We suggest that in the latter configuration, the drainage capacity of the preferential drainage axis was exceeded, promoting the expansion of hydraulically connected regions and local weakening of ice–bed coupling and, hence, enhanced sliding. Text glacier Svalbard Copernicus Publications: E-Journals The Cryosphere 18 6 2939 2968 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The flow of glaciers is largely controlled by changes at the ice–bed interface, where basal slip and sediment deformation drive basal glacier motion. Determining subglacial conditions and their responses to hydraulic forcing remains challenging due to the difficulty of accessing the glacier bed. Here, we monitor the interplay between surface runoff and hydro-mechanical conditions at the base of the Kongsvegen glacier in Svalbard. From July 2021 to August 2022, we measured both subglacial water pressure and till strength. Additionally, we derived median values of subglacial hydraulic gradient and radius of channelized subglacial drainage system from seismic power, recorded at the glacier surface. To characterize the variations in the subglacial conditions caused by changes in surface runoff, we investigate the variations of the following hydro-mechanical properties: measured water pressure, measured sediment ploughing forces, and derived hydraulic gradient and radius, over seasonal, multi-day, and diurnal timescales. We discuss our results in light of existing theories of subglacial hydrology and till mechanics to describe subglacial conditions. We find that during the short, low-melt-rate season in 2021, the subglacial drainage system evolved at equilibrium with runoff, increasing its capacity as the melt season progressed. In contrast, during the long and high-melt-rate season in 2022, the subglacial drainage system evolved transiently to respond to the abrupt and large water supply. We suggest that in the latter configuration, the drainage capacity of the preferential drainage axis was exceeded, promoting the expansion of hydraulically connected regions and local weakening of ice–bed coupling and, hence, enhanced sliding. |
format |
Text |
author |
Bouchayer, Coline Nanni, Ugo Lefeuvre, Pierre-Marie Hult, John Steffensen Schmidt, Louise Kohler, Jack Renard, François Schuler, Thomas V. |
spellingShingle |
Bouchayer, Coline Nanni, Ugo Lefeuvre, Pierre-Marie Hult, John Steffensen Schmidt, Louise Kohler, Jack Renard, François Schuler, Thomas V. Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard |
author_facet |
Bouchayer, Coline Nanni, Ugo Lefeuvre, Pierre-Marie Hult, John Steffensen Schmidt, Louise Kohler, Jack Renard, François Schuler, Thomas V. |
author_sort |
Bouchayer, Coline |
title |
Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard |
title_short |
Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard |
title_full |
Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard |
title_fullStr |
Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard |
title_full_unstemmed |
Multi-scale variations of subglacial hydro-mechanical conditions at Kongsvegen glacier, Svalbard |
title_sort |
multi-scale variations of subglacial hydro-mechanical conditions at kongsvegen glacier, svalbard |
publishDate |
2024 |
url |
https://doi.org/10.5194/tc-18-2939-2024 https://tc.copernicus.org/articles/18/2939/2024/ |
genre |
glacier Svalbard |
genre_facet |
glacier Svalbard |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-18-2939-2024 https://tc.copernicus.org/articles/18/2939/2024/ |
op_doi |
https://doi.org/10.5194/tc-18-2939-2024 |
container_title |
The Cryosphere |
container_volume |
18 |
container_issue |
6 |
container_start_page |
2939 |
op_container_end_page |
2968 |
_version_ |
1810445292585091072 |