f Large-scale Automatic Generation Of Hydrological Input From Resistivities And Boreholes

This study presents a semi-automatic sequential hydrogeophysical inversion method for the integration of resistivity data and lithological borehole information into groundwater models in sedimentary areas. Large scale airborne geophysical EM-surveys play an increasingly important part in the geological mapping of the subsurface especially in a hydrogeological context. Airborne EM surveys provide valuable information of the geological structures and the lateral heterogeneity than boreholes cannot reveal due to the spatial scarcity (Jørgensen et al., 2003). However, boreholes play a key role in linking the resistivity to the different lithological and hydrological classes. Today, geologists and hydrogeologists in most cases interpret AEM-derived electrical resistivity distributions manually along with borehole observations within the context of a given geological setting. Due to the discrepancy between hydrological and geophysical parameter spaces the challenge is to translate the electrical resistivity distribution into hydrogeological classes. Our results suggest that a competitive groundwater model can be constructed from densely sampled resistivity models from AEM surveys together with borehole information, using the procedure outlined below.