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Salinisation d'un aquifère captif côtier en contexte deltaïque - Cas de la Camargue (delta du Rhône, France) -

Abstract : This study deals with the salinization of confined coastal aquifers in relation with sea level variations (past, future) and human pressures.
The deep confined aquifer of Camargue has been studied in the framework of the ORE RESYST. This aquifer shows high salinities reaching that of the Mediterranean Sea near the shoreline. Two approaches have been jointly carried out: (i) an hydrodynamic study in steady and transient flow to understand the hydrogeological behaviour of the aquifer (flows, boundary conditions, hydrodynamic properties) and (ii) a monitoring of hydrochemical and isotopic natural tracers (18O, 2H, 13C TDIC, 3H and 14C TDIC) to determine the origin of the salinity of the aquifer.
This work highlights the influence of the unconfined part of the aquifer (Crau aquifer) on the recharge of the confined aquifer. Thus, the high increase of salinity in the aquifer since 1969 is mainly due to natural or anthropogenic head depletion within the Crau aquifer. The confined aquifer shows rapid pressure transfers both from the Sea and the Rhone River whereas mass transfers are very low.
Ionic and isotopic ratios highlight that strong salinities of the aquifer are due to a freshwater/seawater mixing, which is highly modified by geochemical interactions: cationic exchange, sedimentary organic matter degradation (sulphate reduction, methanogenesis), precipitation phenomena. The mean residence time of water is higher than fifty years and reflects the influence of a former marine intrusion related to the last marine transgression (upper Holocene).
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Contributor : Véronique de Montety <>
Submitted on : Tuesday, November 4, 2008 - 2:51:36 AM
Last modification on : Thursday, December 3, 2020 - 4:50:02 PM
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  • HAL Id : tel-00336417, version 1
  • PRODINRA : 250253

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Véronique de Montety. Salinisation d'un aquifère captif côtier en contexte deltaïque - Cas de la Camargue (delta du Rhône, France) -. Hydrologie. Université d'Avignon, 2008. Français. ⟨tel-00336417⟩

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