Storage characteristics of the Upper Jurassic in Southern Germany with the example of the Blautopf catchment

The Upper Jurassic of Southern Germany is an aquifer of supra-regional importance for water supply. Fractures and karst conduits form a complex system of different storage and drainage functions. It cannot be described by the approach of Maillet. Due to inhomogeneity and anisotropic behaviour, the usual hydraulic approaches to detect permeability and porosity are inadequate on the regional scale. Data on age structure and mean residence time are used to obtain results on the whole aquifer system. The observed storage capacity cannot be explained sufficiently by joints alone. There is an additional system of diagenetically derived porosity. Most probably, the thick unsaturated zone plays an important role too, as far as storage is concerned.