Estimation of hydraulic properties of subglacial till from ploughmeter measurements
Abstract Force variations on a "ploughmeter" and fluctuations in subglacial water pressure have been measured in the same borehole at Storglaciaren, Sweden, to investigate hydraulic properties of the basal till layer. A strong inverse correlation of the pressure and force records, in conju...
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Cambridge University Press (CUP)
1998
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Online Access: | http://dx.doi.org/10.1017/s0022143000002033 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000002033 |
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crcambridgeupr:10.1017/s0022143000002033 2024-09-15T18:15:38+00:00 Estimation of hydraulic properties of subglacial till from ploughmeter measurements Fischer, Urs H. Iverson, Neal R. Hanson, Brian LeB. Hooke, Roger Jansson, Peter 1998 http://dx.doi.org/10.1017/s0022143000002033 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000002033 en eng Cambridge University Press (CUP) Journal of Glaciology volume 44, issue 148, page 517-522 ISSN 0022-1430 1727-5652 journal-article 1998 crcambridgeupr https://doi.org/10.1017/s0022143000002033 2024-08-28T04:03:21Z Abstract Force variations on a "ploughmeter" and fluctuations in subglacial water pressure have been measured in the same borehole at Storglaciaren, Sweden, to investigate hydraulic properties of the basal till layer. A strong inverse correlation of the pressure and force records, in conjunction with a significant lime lag between the two signals, suggests that pore-water pressures directly affect the strength of the till. Variations in sub-glacial water pressure result in potential gradients across the water till interlace at the bottom of the borehole that drive pressure waves downwards through the till layer when the borehole water level is high and back upwards when the water level is low. Analysis of the propagation velocity of this pressure wave indicates that the hydraulic diffusivity of Storglaciaren till is in the range 1.9−3.6 x 10 −6 m 2 s −1 ,in good agreement with estimates obtained in the laboratory. Hydraulic conductivity values associated with these difrusivities are between 10 −9 and 10 −8 ms −1 and thus are well within the range of values for other glacial tills. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 44 148 517 522 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
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English |
description |
Abstract Force variations on a "ploughmeter" and fluctuations in subglacial water pressure have been measured in the same borehole at Storglaciaren, Sweden, to investigate hydraulic properties of the basal till layer. A strong inverse correlation of the pressure and force records, in conjunction with a significant lime lag between the two signals, suggests that pore-water pressures directly affect the strength of the till. Variations in sub-glacial water pressure result in potential gradients across the water till interlace at the bottom of the borehole that drive pressure waves downwards through the till layer when the borehole water level is high and back upwards when the water level is low. Analysis of the propagation velocity of this pressure wave indicates that the hydraulic diffusivity of Storglaciaren till is in the range 1.9−3.6 x 10 −6 m 2 s −1 ,in good agreement with estimates obtained in the laboratory. Hydraulic conductivity values associated with these difrusivities are between 10 −9 and 10 −8 ms −1 and thus are well within the range of values for other glacial tills. |
format |
Article in Journal/Newspaper |
author |
Fischer, Urs H. Iverson, Neal R. Hanson, Brian LeB. Hooke, Roger Jansson, Peter |
spellingShingle |
Fischer, Urs H. Iverson, Neal R. Hanson, Brian LeB. Hooke, Roger Jansson, Peter Estimation of hydraulic properties of subglacial till from ploughmeter measurements |
author_facet |
Fischer, Urs H. Iverson, Neal R. Hanson, Brian LeB. Hooke, Roger Jansson, Peter |
author_sort |
Fischer, Urs H. |
title |
Estimation of hydraulic properties of subglacial till from ploughmeter measurements |
title_short |
Estimation of hydraulic properties of subglacial till from ploughmeter measurements |
title_full |
Estimation of hydraulic properties of subglacial till from ploughmeter measurements |
title_fullStr |
Estimation of hydraulic properties of subglacial till from ploughmeter measurements |
title_full_unstemmed |
Estimation of hydraulic properties of subglacial till from ploughmeter measurements |
title_sort |
estimation of hydraulic properties of subglacial till from ploughmeter measurements |
publisher |
Cambridge University Press (CUP) |
publishDate |
1998 |
url |
http://dx.doi.org/10.1017/s0022143000002033 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000002033 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 44, issue 148, page 517-522 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000002033 |
container_title |
Journal of Glaciology |
container_volume |
44 |
container_issue |
148 |
container_start_page |
517 |
op_container_end_page |
522 |
_version_ |
1810453518560002048 |