Morphological dynamics of an englacial channel
Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last 4 decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut-and-c...
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ftntnutrondheimi:oai:ntnuopen.ntnu.no:11250/2652747 2023-05-15T15:55:50+02:00 Morphological dynamics of an englacial channel Vatne, Geir Irvine-Fynn, Tristram D.L. 2016 application/pdf https://hdl.handle.net/11250/2652747 https://doi.org/10.5194/hess-20-2947-2016 eng eng European Geosciences Union Hydrology and Earth System Sciences. 2016, 20 (7), 2947-2964. urn:issn:1027-5606 https://hdl.handle.net/11250/2652747 https://doi.org/10.5194/hess-20-2947-2016 cristin:1375935 Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no CC-BY 2947-2964 20 Hydrology and Earth System Sciences 7 Peer reviewed Journal article 2016 ftntnutrondheimi https://doi.org/10.5194/hess-20-2947-2016 2020-04-29T22:32:43Z Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last 4 decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut-and-closure" streams, where englacial or subglacial flow paths are created from the long-term incision of supraglacial channels. These flow paths are reported to exhibit step-pool morphology, comprising knickpoints and/or knickzones, exaggerated in dimensions in comparison to supraglacial channels. However, little is known of the development of such channels' morphology. Here, we examine the spatial organisation of step pools and the upstream migration of steps, many of which form knickzones, with repeated surveys over a 10-year period in an englacial conduit in cold-based Austre Brøggerbreen, Svalbard. The observations show upstream step recession to be the dominant process for channel evolution. This is paralleled by an increase in average step height and conduit gradient over time. Characteristic channel-reach types and step-riser forms are consistently observed in each of the morphological surveys reported. We suggest that the formation of steps has a hydrodynamic origin, where step-pool geometry is more efficient for energy dissipation than meanders. The englacial channel system is one in rapid transition towards a quasi-equilibrium form within a decadal timescale. The evolution and recession of knickzones reported here result in the formation of a 37 m deep moulin shaft, suggesting that over time an incising supraglacial channel may evolve towards an englacial channel form exhibiting a stable end-point characterised by a singular vertical descent, which potentially can reach the glacier bed. This challenges the prevailing notions that crevasses or hydrofractures are needed to form deep moulins. Our observations highlight the need to further examine the adjustment processes in cut-and-closure channels to better understand their coupling to supraglacial meltwater sources and potential significance in cold-based glacier hydrology and ice dynamics. publishedVersion © Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License. CC-BY Article in Journal/Newspaper Cold-based glacier glacier Svalbard NTNU Open Archive (Norwegian University of Science and Technology) Svalbard Hydrology and Earth System Sciences 20 7 2947 2964 |
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Open Polar |
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NTNU Open Archive (Norwegian University of Science and Technology) |
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ftntnutrondheimi |
language |
English |
description |
Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last 4 decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut-and-closure" streams, where englacial or subglacial flow paths are created from the long-term incision of supraglacial channels. These flow paths are reported to exhibit step-pool morphology, comprising knickpoints and/or knickzones, exaggerated in dimensions in comparison to supraglacial channels. However, little is known of the development of such channels' morphology. Here, we examine the spatial organisation of step pools and the upstream migration of steps, many of which form knickzones, with repeated surveys over a 10-year period in an englacial conduit in cold-based Austre Brøggerbreen, Svalbard. The observations show upstream step recession to be the dominant process for channel evolution. This is paralleled by an increase in average step height and conduit gradient over time. Characteristic channel-reach types and step-riser forms are consistently observed in each of the morphological surveys reported. We suggest that the formation of steps has a hydrodynamic origin, where step-pool geometry is more efficient for energy dissipation than meanders. The englacial channel system is one in rapid transition towards a quasi-equilibrium form within a decadal timescale. The evolution and recession of knickzones reported here result in the formation of a 37 m deep moulin shaft, suggesting that over time an incising supraglacial channel may evolve towards an englacial channel form exhibiting a stable end-point characterised by a singular vertical descent, which potentially can reach the glacier bed. This challenges the prevailing notions that crevasses or hydrofractures are needed to form deep moulins. Our observations highlight the need to further examine the adjustment processes in cut-and-closure channels to better understand their coupling to supraglacial meltwater sources and potential significance in cold-based glacier hydrology and ice dynamics. publishedVersion © Author(s) 2016. This work is distributed under the Creative Commons Attribution 3.0 License. CC-BY |
format |
Article in Journal/Newspaper |
author |
Vatne, Geir Irvine-Fynn, Tristram D.L. |
spellingShingle |
Vatne, Geir Irvine-Fynn, Tristram D.L. Morphological dynamics of an englacial channel |
author_facet |
Vatne, Geir Irvine-Fynn, Tristram D.L. |
author_sort |
Vatne, Geir |
title |
Morphological dynamics of an englacial channel |
title_short |
Morphological dynamics of an englacial channel |
title_full |
Morphological dynamics of an englacial channel |
title_fullStr |
Morphological dynamics of an englacial channel |
title_full_unstemmed |
Morphological dynamics of an englacial channel |
title_sort |
morphological dynamics of an englacial channel |
publisher |
European Geosciences Union |
publishDate |
2016 |
url |
https://hdl.handle.net/11250/2652747 https://doi.org/10.5194/hess-20-2947-2016 |
geographic |
Svalbard |
geographic_facet |
Svalbard |
genre |
Cold-based glacier glacier Svalbard |
genre_facet |
Cold-based glacier glacier Svalbard |
op_source |
2947-2964 20 Hydrology and Earth System Sciences 7 |
op_relation |
Hydrology and Earth System Sciences. 2016, 20 (7), 2947-2964. urn:issn:1027-5606 https://hdl.handle.net/11250/2652747 https://doi.org/10.5194/hess-20-2947-2016 cristin:1375935 |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/hess-20-2947-2016 |
container_title |
Hydrology and Earth System Sciences |
container_volume |
20 |
container_issue |
7 |
container_start_page |
2947 |
op_container_end_page |
2964 |
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1766391327386238976 |