3D geological & geophysical modelling of Plateau de Sault (Eastern Pyrenees) for good water management

Abstract : Better constrain the geological geometries in 3 dimensions aids to improve subsequent hydrological modeling and simulations. The project "Plateau de Sault" (Eastern Pyrenees) aims to provide a better estimate and management of water resources of the region. The water flow occurs mostly underground via significant karst networks in a complex tectonic framework. Thus, a 3D geological model was built, as a prerequisite for hydrological studies, with the 3D GeoModeller software (©BRGM-Intrepid Geophysics) which is unique in interpolating complex geology using a potential field method. The construction of this 3D geological model has 3 main objectives: improve regional geology's knowledge, propose geometries for limestone urgonian bars and define hypothetical connections between different aquifers. Structures at depth have been constrained by direct calculation and gravimetric inversion of the geological model thanks to newly acquired gravimetric data (around 250 stations) and densities of formations established in laboratory from 52 rocks sampled in the field. This study demonstrates the importance of integrative tools as 3D geological modeling for good water management.