Effects of basal topography and ice-sheet surface slope in a subglacial glaciofluvial deposition model

• Published in: Journal of Glaciology
• Main Authors: David Stevens, Jeremy C. Ely, Stephen J. Livingstone, Chris D. Clark, Frances E. G. Butcher, Ian Hewitt
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2023
• Subjects: Glacial geomorphology; glacier hydrology; melt – basal; subglacial processes; subglacial sediments; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Ice Sheet; Journal of Glaciology
• Online Access: https://doi.org/10.1017/jog.2022.71; https://doaj.org/article/c59b7032f5364ab5af694bd8238cb5d2

We use a mathematical model to investigate the effect of basal topography and ice surface slope on transport and deposition of sediment within a water-filled subglacial channel. In our model, three zones of different behaviour occur. In the zone furthest upstream, variations in basal topography lead to sediment deposition under a wide range of conditions. In this first zone, even very small and gradually varying basal undulations (~5 m amplitude) can lead to the deposition of sediment within a modelled channel. Deposition is concentrated on the downstream gradient of subglacial ridges, and on the upstream gradient of subglacial troughs. The thickness and steepness of the ice sheet has a substantial impact on deposition rates, with shallow ice profiles strongly promoting both the magnitude and extent of sediment deposition. In a second zone, all sediment is transported downstream. Finally, a third zone close to the ice margin is characterised by high rates of sediment deposition. The existence of these zones has implications for esker formation and the dynamics of the subglacial environment.