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Drinking water supply and mineralized groundwaters in the Aquitaine Basin (SW France): hydrodynamic and geochemical processes of acquisition of the mineralization

Abstract : One of the main resources for drinking water in the sedimentary Aquitaine Basin (SW France) is the Eocene aquifer including several geological layers, which have different lithological, mineralogical and hydrodynamic properties. In this aquifer, mostly confined, a large area has been identified with high salinity and with anomalous levels of critical elements, such as sulfates and fluorides. This led to difficulties for the resource exploitation for drinking water supply of the population. Since the 1900′s, many boreholes in the area for drinking water supply have locally modified the natural water flows of the system. This work has allowed i) understanding the origin of the mineralization of the waters, geochemical and isotopic characterization of groundwaters showed a common origin of the mineralization in all the study area; ii) identifying exactly the location of the minerals bearing sulfates and fluorides (gypsum, fluorite) within the layer defined as the Eocene aquifer; iii) constraint the geochemical and hydrodynamic processes. Finally, it allows defining and improving for the way for a sustainable management for drinking water resource in South-West of France. To understand the acquisition of the groundwaters' geochemistry, it is necessary to consider the lateral and vertical variations in facies and mineralogy, geochemical processes (mineral dissolution and/or precipitation, phenomenon of diffusion in contact with low permeability and mineralized layers) and local fluid mixing processes within the borehole and its immediate surroundings. Our investigation also showed the need for a precise and detailed knowledge of the vertical distribution of the hydrodynamic and geochemical properties of each layer. Indeed, the average concentration in the borehole water depends on the 10-3 to 1 meter scale variation of water fluxes and concentrations. Geochemical models, presented here, fully explain the composition of groundwaters across the study area and improve the understanding of geochemical processes taking place at the borehole scale
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Contributeur : Emmanuelle Petelet-Giraud Connectez-vous pour contacter le contributeur
Soumis le : mercredi 3 octobre 2012 - 18:53:23
Dernière modification le : mardi 2 août 2022 - 16:16:51


  • HAL Id : hal-00738256, version 1



Eline Malcuit, Olivier Atteia, Michel Franceschi, Philippe Négrel, Emmanuelle Petelet-Giraud. Drinking water supply and mineralized groundwaters in the Aquitaine Basin (SW France): hydrodynamic and geochemical processes of acquisition of the mineralization. AGU Fall Meeting, Dec 2012, San Francisco, United States. pp.H31B-1111. ⟨hal-00738256⟩



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