Sediment behavior controls equilibrium width of subglacial channels
ABSTRACT Flow-frictional resistance at the base of glaciers and ice sheets is strongly linked to subglacial water pressure. Understanding the physical mechanisms that govern meltwater fluxes in subglacial channels is hence critical for constraining variations in ice flow. Previous mathematical descr...
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crcambridgeupr:10.1017/jog.2017.71 2024-09-15T18:15:38+00:00 Sediment behavior controls equilibrium width of subglacial channels DAMSGAARD, ANDERS SUCKALE, JENNY PIOTROWSKI, JAN A. HOUSSAIS, MORGANE SIEGFRIED, MATTHEW R. FRICKER, HELEN A. 2017 http://dx.doi.org/10.1017/jog.2017.71 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143017000715 en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by-nc-sa/4.0/ Journal of Glaciology volume 63, issue 242, page 1034-1048 ISSN 0022-1430 1727-5652 journal-article 2017 crcambridgeupr https://doi.org/10.1017/jog.2017.71 2024-09-04T04:03:47Z ABSTRACT Flow-frictional resistance at the base of glaciers and ice sheets is strongly linked to subglacial water pressure. Understanding the physical mechanisms that govern meltwater fluxes in subglacial channels is hence critical for constraining variations in ice flow. Previous mathematical descriptions of soft-bed subglacial channels assume a viscous till rheology, which is inconsistent with laboratory data and the majority of field studies. Here, we use a grain-scale numerical formulation coupled to pore-water dynamics to analyze the structural stability of channels carved into soft beds. Contrary to the soft-bed channel models assuming viscous till rheology, we show that the flanks of till channels can support substantial ice loads without creep closure of the channel, because the sediment has finite frictional strength. Increased normal stress on the channel flanks causes plastic failure of the sediment, and the channel rapidly shrinks to increase the ice-bed contact area. We derive a new parameterization for subglacial channelized flow on soft beds and show that channel dynamics are dominated by fluvial erosion and deposition processes with thresholds linked to the plastic rheology of subglacial tills. We infer that the described limits to channel size may cause subglacial drainage to arrange in networks of multiple closely spaced channels. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 63 242 1034 1048 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
ABSTRACT Flow-frictional resistance at the base of glaciers and ice sheets is strongly linked to subglacial water pressure. Understanding the physical mechanisms that govern meltwater fluxes in subglacial channels is hence critical for constraining variations in ice flow. Previous mathematical descriptions of soft-bed subglacial channels assume a viscous till rheology, which is inconsistent with laboratory data and the majority of field studies. Here, we use a grain-scale numerical formulation coupled to pore-water dynamics to analyze the structural stability of channels carved into soft beds. Contrary to the soft-bed channel models assuming viscous till rheology, we show that the flanks of till channels can support substantial ice loads without creep closure of the channel, because the sediment has finite frictional strength. Increased normal stress on the channel flanks causes plastic failure of the sediment, and the channel rapidly shrinks to increase the ice-bed contact area. We derive a new parameterization for subglacial channelized flow on soft beds and show that channel dynamics are dominated by fluvial erosion and deposition processes with thresholds linked to the plastic rheology of subglacial tills. We infer that the described limits to channel size may cause subglacial drainage to arrange in networks of multiple closely spaced channels. |
format |
Article in Journal/Newspaper |
author |
DAMSGAARD, ANDERS SUCKALE, JENNY PIOTROWSKI, JAN A. HOUSSAIS, MORGANE SIEGFRIED, MATTHEW R. FRICKER, HELEN A. |
spellingShingle |
DAMSGAARD, ANDERS SUCKALE, JENNY PIOTROWSKI, JAN A. HOUSSAIS, MORGANE SIEGFRIED, MATTHEW R. FRICKER, HELEN A. Sediment behavior controls equilibrium width of subglacial channels |
author_facet |
DAMSGAARD, ANDERS SUCKALE, JENNY PIOTROWSKI, JAN A. HOUSSAIS, MORGANE SIEGFRIED, MATTHEW R. FRICKER, HELEN A. |
author_sort |
DAMSGAARD, ANDERS |
title |
Sediment behavior controls equilibrium width of subglacial channels |
title_short |
Sediment behavior controls equilibrium width of subglacial channels |
title_full |
Sediment behavior controls equilibrium width of subglacial channels |
title_fullStr |
Sediment behavior controls equilibrium width of subglacial channels |
title_full_unstemmed |
Sediment behavior controls equilibrium width of subglacial channels |
title_sort |
sediment behavior controls equilibrium width of subglacial channels |
publisher |
Cambridge University Press (CUP) |
publishDate |
2017 |
url |
http://dx.doi.org/10.1017/jog.2017.71 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143017000715 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 63, issue 242, page 1034-1048 ISSN 0022-1430 1727-5652 |
op_rights |
http://creativecommons.org/licenses/by-nc-sa/4.0/ |
op_doi |
https://doi.org/10.1017/jog.2017.71 |
container_title |
Journal of Glaciology |
container_volume |
63 |
container_issue |
242 |
container_start_page |
1034 |
op_container_end_page |
1048 |
_version_ |
1810453515063001088 |