THE EFFECTS OF PLEISTOCENE GLACIATIONS ON THE GEOHYDROLOGICAL SYSTEM OF NORTHWEST EUROPE

A large-scale hydrological model study is carried out to investigate t he geohydrological responses to glacial climate conditions in Northwes t Europe. The vertically integrated groundwater model is based on a su praregional hydrogeological model of the Cenozoic and Mesozoic subsurf ace in Northwest Europe. Three different layers are distinguished abov e the relatively impervious base of Palaeozoic and Precambrian rocks, Boundary conditions are inferred from indicative palaeoenvironmental r econstructions of the last three glacial cycles to simulate groundwate r flow related to ice sheet expansions into the Northwest European low lands. Recharge of the groundwater system due to basal glacial melting is deduced from ice sheet model simulations driven by a transient cli mate function. Results of the large-scale model study show relatively high groundwater velocities and pressures in the subglacial areas and the ice-marginal permafrost areas. Extreme high velocities may develop when the ice sheet has advanced to the southern margins of the upper Plio/Pleistocene aquifer in Northwest Europe. Drainage of the highly p ressurized groundwater system mainly occurs in proglacial ice-dammed l akes, ice-marginal seas and zones of discontinuous permafrost, includi ng river valleys.