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Flotation and free surface flow in a model for subglacial drainage. Part 2. Channel flow

Published online by Cambridge University Press:  23 May 2012

I. J. Hewitt ,
C. Schoof  and
M. A. Werder
I. J. Hewitt*
Affiliation:
Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, BC, Canada V6T 1Z2
C. Schoof
Affiliation:
Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC, Canada V6T 1Z4
M. A. Werder
Affiliation:
Department of Earth Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
*
†Email address for correspondence: hewitt@math.ubc.ca
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Abstract

We present a new model of subglacial drainage incorporating flow in a network of channels and a porous sheet, with water exchange between the two determined by pressure gradients. The sheet represents the average effect of many linked cavities, whilst the channels emerge from individual cavities that enlarge due to dissipation-induced melting. The model distinguishes cases when the water pressure drops to zero, in which case it allows for the drainage space to be only partially filled with water (free surface flow), and when the pressure reaches the ice overburden pressure, in which case it allows for uplift of the ice to whatever extent is needed to accommodate the water (flotation). Numerical solutions are found for a one-dimensional flow-line version of the model. The results capture typically observed or inferred features of subglacial drainage systems, including open channel flow at the ice margin, seasonal channel evolution, and high water pressures and uplift of the ice surface driven by rapid changes in water supply.

JFM classification

Geophysical and Geological Flows: Ice sheets Mathematical Foundations: Variational methods

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Type
Papers
Information
Journal of Fluid Mechanics , Volume 702 , 10 July 2012 , pp. 157 - 187
Copyright
Copyright © Cambridge University Press 2012

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