TOWARDS A HYDROLOGICAL MODEL FOR COMPUTERIZED ICE-SHEET SIMULATIONS

Ice-sheet modelling typically uses grid cells 10 km or more on a side, so any hydrological and sliding model must average or parameterize pr ocesses that vary over shorter distances than this. Observations and t heory suggest that basally produced water remains in a distributed, hi gh-pressure system unless it encounters low-pressure channels fed by s urface melt. Such distributed systems appear to exhibit increasing wat er storage, water transmission and water lubrication of sliding with i ncreasing water pressure. A model based on these assumptions successfu lly simulates some aspects of the non-steady response of mountain glac iers to externally forced channel-pressure variations; it merits testi ng in ice-sheet modelling.