MODELING SUBGLACIAL GROUNDWATER ALONG A FLOW LINE OF THE SCANDINAVIAN ICE SHEET

Several aspects of the Scandinavian Ice Sheet (SIS) are still poorly understood and yet are also critical components for the reconstruction of climate during the last glacial period. The behavior of the subglacial groundwater system is a critical glaciological constraint. It influences the stability of the ice sheet, ice sheet thickness, and extent. We use a MODFLOW-based groundwater model of the subglacial hydrology along a flow line of the Scandinavian Ice Sheet to examine the water production and discharge from the ice. The model is two-dimensional in profile, assuming that groundwater flow is parallel to the ice flow line, since groundwater head is ice-directed. A two-dimensional ice flow model provides the basal meltwater input along the flow line. Simulations for times during advance and retreat, as well as the glacial maximum, indicate that the substrate alone would not have been capable of transmitting all of the meltwater out of the fjord. The development of a drainage network would have aided in the evacuation of meltwater from the system, keeping basal water pressures at reasonable levels, and controlling the development of subglacial landforms, such as tunnel channels or eskers. Additional recharge derived from surface meltwater would have also had a great impact on the underlying aquifer, and might explain non-climatically driven margin readvances during the overall retreat phase.