Modelling distributed and channelized subglacial drainage: The spacing of channels

• Published in: Journal of Glaciology
• Main Author: Hewitt, I
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Ice Sheet
• Online Access: https://doi.org/10.3189/002214311796405951; https://ora.ox.ac.uk/objects/uuid:e54f3548-ebdf-4dd9-9572-c52a8acd90b1

Models are proposed for channelized and distributed flow of meltwater at the base of an ice sheet. The volumes of both channel and distributed systems evolve according to a competition between processes that open drainage space (e.g. sliding over bedrock,melting of the ice) and processes that close it (e.g. viscous creep of the ice due to a positive effective pressure). Channels are generally predicted to have lower water pressure and therefore capture water from the surrounding regions of distributed flow. There is a natural length scale associated with the distributed system that determines the width of the bed from which water can be drawn into a channel. It is suggested that this determines the spacing between major channels and that this may be reflected in the spacing of eskers. A more permeable distributed system results in more widely spaced, and therefore larger, channels. Calculations of the flow into the head of a channel reveal that there is a critical discharge necessary for it to form, and provide a criterion for where channels can exist.