Explaining the groundwater salinity of hard-rock aquifers in semi-arid hinterlands using a multidisciplinary approach

Kreis Marjorie B., Taupin Jean-Denis, Patris Nicolas, Vergnaud-Ayraud Virginie, Leduc Christian, Lachassagne Patrick, Burte Julien, Martins Eduardo Sávio Passos Rodrigues. 2023. Explaining the groundwater salinity of hard-rock aquifers in semi-arid hinterlands using a multidisciplinary approach. Hydrological Sciences Journal, 68 (15) : 2189-2207.

Résumé : Shallow crystalline groundwater in the semi-arid hinterland of Ceará is brackish or saline with mixed chloride or sodium chloride facies. Very few hydrochemical data are available for the area and the drivers behind this salinity are not clearly identified. In this study, extensive field data collection was performed to provide new information about the hydrogeological functioning and the salinization processes, through the implementation of piezometric, hydrogeochemical, isotopic (18O, 2H) and multitracer dating (14C, 3H, CFC, SF6) monitoring. Piezometric and isotopic data evidence fast flow circulation processes and a high contribution of evaporated surface water to aquifer recharge. Multitracer dating shows the groundwater is essentially composed of seasonal vertical infiltration flows that mix with older waters stored in the aquifer. Chemical analyses suggest the groundwater, originally low mineralized, has become progressively saltier due to leaching of salts that were evapoconcentrated in either surface waters or the unsaturated zone during drier periods.

Mots-clés Agrovoc : eau souterraine, variation saisonnière, bassin versant, eau de pluie, circulation en surface

Mots-clés géographiques Agrovoc : Brésil, France

Mots-clés libres : Hydrogeology, Hardrock, Aquifers, Semi-arid climate, Salinization, Isotopes, Environmental tracers, Groundwater dating, Hydrochemistry, Brazil

Classification Agris : P10 - Ressources en eau et leur gestion

Champ stratégique Cirad : CTS 5 (2019-) - Territoires

Agences de financement hors UE : Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico, Fundação Cearense de Meteorologia e Recursos Hídricos

Auteurs et affiliations

• Kreis Marjorie B., Université de Montpellier (FRA) - auteur correspondant
• Taupin Jean-Denis, Université de Montpellier (FRA)
• Patris Nicolas, Université de Montpellier (FRA)
• Vergnaud-Ayraud Virginie, Université de Rennes (FRA)
• Leduc Christian, IRD (FRA)
• Lachassagne Patrick, IRD (FRA)
• Burte Julien, CIRAD-ES-UMR G-EAU (MAR) ORCID: 0000-0001-7912-5137
• Martins Eduardo Sávio Passos Rodrigues, Universidade Federal do Ceara (BRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/608585/)

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