HR: 1340h
AN: H23A-1004    [Abstracts]
TI: Geophysical mapping of buried valley aquifer systems: the project BurVal
AU: Wiederhold, H
EM: Helga.Wiederhold@gga-hannover.de
AF: Leibniz Institute for Applied Geosciences (GGA), Stilleweg 2, Hannover, D-30655, Germany
AU: Working Group, B
AU: * Krawczyk, C M
EM: lotte@gga-hannover.de
AF: Leibniz Institute for Applied Geosciences (GGA), Stilleweg 2, Hannover, D-30655, Germany
AB: Sub-glacial erosion during the ice ages carved deep valleys down to 400 m depth into the Tertiary subsurface of the Permian sedimentary basins in Northern and Central Europe. These valleys are several km wide and extend over distances of up to 100 km. Refilled with glacial material (sand and till), they can have complex internal structures which are furthermore difficult to image. Despite this, buried valleys can have an important influence on groundwater conditions: if sandy material dominates the valley fill, this may host important groundwater reservoirs which are increasingly used for water supply. Targets for geophysical exploration of buried valleys are: 1) localisation and lateral extent (the valley is not visible at the surface), 2) shape and depth extent, 3) composition of the valley fill in terms of aquifers and impermeable layers, 4) structure of the covering layers in order to quantify the aquifer vulnerability. Within the EU-project BurVal six buried valleys in Denmark, Northern Germany and the Netherlands were intensely investigated with geophysical and hydrogeological methods, including reflection seismics, gravity, ground-based resistivity and airborne electromagnetic methods (time- and frequency domain). Fieldwork and data interpretations were carried out by GEUS (Geological Survey of Denmark and Greenland, Copenhagen), University of Aarhus, University of Kiel, BGR, GGA-Institute of Applied Geosciences (both Hannover, Germany), TNO (Geological Survey of the Netherlands, Utrecht) and some private contractors. Combined with drilling results, the geophysical results were used to construct geological models of the valley which can be used for groundwater modelling. Results of the investigation program showing the combined use of geophysical techniques to characterize buried valleys are presented and discussed.
DE: 0900 EXPLORATION GEOPHYSICS
DE: 0935 Seismic methods (3025, 7294)
DE: 1835 Hydrogeophysics
SC: Hydrology [H]
MN: 2007 Fall Meeting