Multi-scale aquifer characterization. From outcrop analogue, direct-push and borehole investigations towards improved groundwater flow models

A methodology is developed for efficient multi-scale subsurface characterization and integration of the gathered data in a stochastic regional groundwater flow and solute transport modelling approach. Different kinds of aquifer characterization technologies have to be combined to cover the centimetre- to the kilometre-scale, and to make optimal use of common or easily gathered secondary data. This is achieved by using different kinds of measurements from outcrop analogues, borehole and direct-push investigations, and by using innovative methods and techniques to obtain a sound framework for integrating all data. The case study that we use is an area of ~60 km² in Mol/Dessel, Belgium, of which the subsurface consists of a succession of dipping lithostratigraphical units with varying degrees of heterogeneity. We make use of different previous hydrogeological studies that were performed in the framework of the ONDRAF/NIRAS radioactive waste disposal programmes, and performed additional site characterization. The developed methodology, and unique combination of datasets prove to be very useful for characterization of the current study area. The integration of all data in a groundwater flow model led to improved knowledge on the studied hydrogeological system, as well as a decrease in the uncertainties related to solute transport.