Modeling channelized and distributed subglacial drainage in two dimensions

Mauro A Werder, Ian J Hewitt, Christian G Schoof, Gwenn E Flowers

Research output: Contribution to journalArticle (Academic Journal)peer-review

141 Citations (Scopus)

Abstract

We present a two-dimensional Glacier Drainage System model (GlaDS)
that couples distributed and channelized subglacial water flow.
Distributed flow occurs through linked cavities that are represented
as a continuous water sheet of variable thickness. Channelized flow
occurs through R\"othlisberger channels that can form on any of the
edges of a prescribed, unstructured network of potential channels.
Water storage is accounted for in an englacial aquifer and in
moulins, which also act as point sources of water to the subglacial
system. Solutions are presented for a synthetic topography designed
to mimic an ice-sheet margin. For low discharge all the flow is
accommodated in the sheet whereas for sufficiently high discharge,
the model exhibits a channelization instability which leads to the
formation of a self-organized channel system. The random
orientation of the network edges allows the channel-system geometry
to be relatively unbiased, in contrast to previous structured
grid-based models. Under steady conditions, the model supports the
classical view of the subglacial drainage system, with low pressure
regions forming around the channels. Under diurnally varying input,
water flows in and out of the channels, and a rather complex
spatiotemporal pattern of water pressures is predicted. We explore
the effects of parameter variations on the channel-system topology
and mean effective pressure. The model is then applied to a
mountain glacier and forced with meltwater calculated by a
temperature index model. The results are broadly consistent with
our current understanding of the glacier drainage system and
demonstrate the applicability of the model to real settings.
Original languageEnglish
Pages (from-to)1-19
Number of pages19
JournalJournal of Geophysical Research: Earth Surface
Volume118
Early online date16 Oct 2013
DOIs
Publication statusPublished - 2013

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