Drenaż subglacjalny i jego wpływ na dynamikę lobu Odry zlodowacenia wisły

Abstract

Subglacial drainage and its influence on the dynamics of the Weichselian Odra lobe.A b s t r a c t. In this paper we have analyzed the influence of the Weichselian ice sheet advance on the groundwater system in the Odra lobe area using hydrogeological numerical modelling performed with the finite difference method. The results indicate entire re-organization of the groundwater system in relation to non glacial times mainly affecting the flow directions, velocities and fluxes. The re-organization of groundwater flow was caused by the pressure gradient imposed by the sloping ice sheet surface especially obvious under the ice margin and some distance in front of it. Simulated groundwater flow velocities are significantly higher than the present velocities in that area while the major groundwater flow direction is to the south, i.e. opposite to the present direction. Coupling the simulation results with assumed basal melting rate suggests that only a small fraction of basal meltwater (~24%) could have drained through the bed. The surplus water likely accumulated at the ice/bed interface facilitating faster ice flow of the Odra lobe due to enhanced basal sliding and bed deformation.