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 processes that vary over shorter distances than this. Observations and theory suggest that basally produced water remains in a distributed, high-pressure system unless it encounters low-pressure channel fed by surface melt. Such distributed systems appear to exhibit increasing water storage, water transmission and water lubrication of sliding with increasing water pressure. A model based on these assumptions successfully simulates some aspects of the non-steady response of mountain glaciers to externally forced channel-pressure variations; it merits testing in ice-sheet modelling.