Coupling the flow of ice, water, and sediment in a glacial landscape evolution model

The processes of subglacial erosion depend not only on the sliding motion of glaciers over bedrock but also on the presence of meltwater and sediment in the subglacial environment. In particular, theoretical models for subglacial quarrying and abrasion, as well as hypothesized erosion thresholds associated with subglacial sediment transport, include both positive and negative effects of subglacial water and sediment on the rate of erosion. In order to incorporate the existing theoretical models for subglacial erosion by quarrying and abrasion in a long-term glacial landscape evolution model, we here present a coupled computational framework for simulating the simultaneous flow processes of ice, water, and sediment. We supplement a higher order ice sheet model with simple long-term models for glacial hydrology and subglacial sediment transport, as well as fluvial and hillslope-related erosion processes. An important strength of the modeling framework presented relates to the morphological detail of the landscapes produced, which facilitates direct comparison with existing landforms. This improves the connection between glacial landscape evolution models, geomorphological observations, and the existing knowledge of the physical processes that operate under glaciers. We demonstrate with model examples, how increased basal meltwater pressure and transport-limited subglacial erosion lead to both positive and negative feedbacks related to glacial erosion and the formation of overdeepenings. (C) 2011 Elsevier B.V. All rights reserved.