The department of Physical Geography and Geological Survey of the Netherlands TNO are searching for a PhD candidate with the aim to improve the characterization of hydraulic conductivity for the hydrogeological models of the Dutch subsurface.
Hydraulic conductivity of aquifers and aquitards is a basic information need for hydrogeologists. The Geological Survey of the Netherlands TNO (TNO-GSN) makes estimates of hydraulic properties of the subsurface available at http://www.dinoloket.nl as part of the GeoTOP model (subsurface until 50 m below the surface) and the national, hydrogeological model REGIS (down to geohydrological basis). TNO-GSN has carried out a characterization of hydraulic parameters of groundwater aquifers and aquitards at different resolutions. Laboratory measurements of hydraulic conductivity on cm-scale samples from different sedimentary facies in various geologic formations have served as basis for these characterizations. Using stochastic simulation of fine-scale (0.5m x 0.5m x 0.25m) texture variations within facies, these values have subsequently been upscaled to larger voxels (25m x 25m x 0.5m) and finally to transmissivity and vertical hydraulic resistance values. It is yet unknown to what extent these upscaled conductivity values are representative for the scales of groundwater investigations. These scales range from local (a single parcel or building pit) via regional (such as groundwater protection areas or large infrastructural interventions) to national (e.g. the Dutch policy on water supply). A PhD project is commissioned by TNO GSN to Utrecht University in order to further establish and validate scientific but practical methodologies for characterisation of hydraulic conductivity at various resolutions.
The main objective of the PhD project is: to develop a method to correctly assess the hydraulic conductivity distribution for the (hydro)geological data models GeoTOP and REGIS at the relevant resolutions and spatial extent that GeoTOP and REGIS are commonly used. This method should be cost-effective and able to use existing information about hydraulic conductivity that is present in the current GeoTOP and REGIS databases. The general idea is to devise a method that is able to use both existing and new laboratory measurements, dedicated and existing pumping tests and groundwater abstraction data that are available from drinking water production wells.
