f Geophysical radar techniques for the characterization of heterogeneous quarternary gravel deposits

Quarternary gravel deposits build up most of the valley aquifers in central Europe and elsewhere. In order to understand and model groundwater flow and contaminant transport in these highly heterogeneous systems, a detailed geometrical image of the subsurface and the hydrogeological parameter distribution within it is needed. Geophysical radar techniques are able to identify sedimentological structures in three dimensions and to fill elements with physical parameters. Ground-penetrating radar (GPR) is a common geophysical tool to resolve sedimentary structures in unconsolidated sediments (e.g. Huggenberger, 1993). It has the potential to visualise the deposits in three dimensions (Beres, 1998). Applying 3-D GPR at a research site in the Neckar River Valley, SW Germany, we were able to get a high resolution structural image of the shallow subsurface. Sedimentological units and their spatial extension could be interpreted. Using crosshole radar tomography at the same site, made it possible to reproduce parts of certain prominent structural elements identified in the surface measurements and to fill them with geophysical parameters.