Water Pressure in Intra- and Subglacial Channels
Abstract Water flowing in tubular channels inside a glacier produces frictional heat, which causes melting of the ice walls. However the channels also have a tendency to close under the overburden pressure. Using the equilibrium equation that at every cross-section as much ice is melted as flows in,...
Published in: | Journal of Glaciology |
---|---|
Main Author: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
1972
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1017/s0022143000022188 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000022188 |
id |
crcambridgeupr:10.1017/s0022143000022188 |
---|---|
record_format |
openpolar |
spelling |
crcambridgeupr:10.1017/s0022143000022188 2024-05-19T07:43:14+00:00 Water Pressure in Intra- and Subglacial Channels Röthlisberger, Hans 1972 http://dx.doi.org/10.1017/s0022143000022188 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000022188 en eng Cambridge University Press (CUP) Journal of Glaciology volume 11, issue 62, page 177-203 ISSN 0022-1430 1727-5652 journal-article 1972 crcambridgeupr https://doi.org/10.1017/s0022143000022188 2024-04-25T06:51:17Z Abstract Water flowing in tubular channels inside a glacier produces frictional heat, which causes melting of the ice walls. However the channels also have a tendency to close under the overburden pressure. Using the equilibrium equation that at every cross-section as much ice is melted as flows in, differential equations are given for steady flow in horizontal, inclined and vertical channels at variable depth and for variable discharge, ice properties and channel roughness. It is shown that the pressure decreases with increasing discharge, which proves that water must flow in main arteries. The same argument is used to show that certain glacier lakes above long flat valley glaciers must form in times of low discharge and empty when the discharge is high, i.e. when the water head in the subglacial drainage system drops below the lake level. Under the conditions of the model an ice mass of uniform thickness does not float, i.e. there is no water layer at the bottom, when the bed is inclined in the down-hill direction, but it can float on a horizontal bed if the exponent n of the law for the ice creep is small. It is further shown that basal streams (bottom conduits) and lateral streams at the hydraulic grade line (gradient conduits) can coexist. Time-dependent flow, local topography, ice motion, and sediment load are not accounted for in the theory, although they may strongly influence the actual course of the water. Computations have been carried out for the Gornergletscher where the bed topography is known and where some data are available on subglacial water pressure. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 11 62 177 203 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
description |
Abstract Water flowing in tubular channels inside a glacier produces frictional heat, which causes melting of the ice walls. However the channels also have a tendency to close under the overburden pressure. Using the equilibrium equation that at every cross-section as much ice is melted as flows in, differential equations are given for steady flow in horizontal, inclined and vertical channels at variable depth and for variable discharge, ice properties and channel roughness. It is shown that the pressure decreases with increasing discharge, which proves that water must flow in main arteries. The same argument is used to show that certain glacier lakes above long flat valley glaciers must form in times of low discharge and empty when the discharge is high, i.e. when the water head in the subglacial drainage system drops below the lake level. Under the conditions of the model an ice mass of uniform thickness does not float, i.e. there is no water layer at the bottom, when the bed is inclined in the down-hill direction, but it can float on a horizontal bed if the exponent n of the law for the ice creep is small. It is further shown that basal streams (bottom conduits) and lateral streams at the hydraulic grade line (gradient conduits) can coexist. Time-dependent flow, local topography, ice motion, and sediment load are not accounted for in the theory, although they may strongly influence the actual course of the water. Computations have been carried out for the Gornergletscher where the bed topography is known and where some data are available on subglacial water pressure. |
format |
Article in Journal/Newspaper |
author |
Röthlisberger, Hans |
spellingShingle |
Röthlisberger, Hans Water Pressure in Intra- and Subglacial Channels |
author_facet |
Röthlisberger, Hans |
author_sort |
Röthlisberger, Hans |
title |
Water Pressure in Intra- and Subglacial Channels |
title_short |
Water Pressure in Intra- and Subglacial Channels |
title_full |
Water Pressure in Intra- and Subglacial Channels |
title_fullStr |
Water Pressure in Intra- and Subglacial Channels |
title_full_unstemmed |
Water Pressure in Intra- and Subglacial Channels |
title_sort |
water pressure in intra- and subglacial channels |
publisher |
Cambridge University Press (CUP) |
publishDate |
1972 |
url |
http://dx.doi.org/10.1017/s0022143000022188 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000022188 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 11, issue 62, page 177-203 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000022188 |
container_title |
Journal of Glaciology |
container_volume |
11 |
container_issue |
62 |
container_start_page |
177 |
op_container_end_page |
203 |
_version_ |
1799482945707180032 |