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Salinization of groundwater in the Nefzawa oases region, Tunisia: results of a regional-scale hydrogeologic approach

Zammouri, Mounira ; Siegfried, Tobias ; El-Fahem, Tobias ; Kriâa, Samiha ; Kinzelbach, Wolfgang

In: Hydrogeology Journal, 2007, vol. 15, no. 7, p. 1357-1375

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    Titre
    • Salinization of groundwater in the Nefzawa oases region, Tunisia: results of a regional-scale hydrogeologic approach
    Auteur
    • Zammouri, Mounira. Ecole Superieure des Ingénieurs de l'Equipement Rural de Medjez el Bab, Route du Kef, Km 5, 9070, Medjez el Bab, Tunisia
    • Siegfried, Tobias. Institute of Environmental Engineering, Swiss Federal Institute of Technology, Wolfgang-Pauli Strasse 15, CH-8093, Zürich, Switzerland
    • El-Fahem, Tobias. Institute of Geology, University of Bonn, Nussallee 8, 53115, Bonn, Germany
    • Kriâa, Samiha. Laboratoire de Modélisation en Hydraulique et Environnement, Ecole Nationale d'Ingénieurs de Tunis, B.P.37 le Belvédère 1002, Tunis, Tunisia
    • Kinzelbach, Wolfgang. Institute of Environmental Engineering, Swiss Federal Institute of Technology, Wolfgang-Pauli Strasse 15, CH-8093, Zürich, Switzerland
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:310564
    Summary
    Groundwater pumped from the semi-confined Complexe Terminal (CT) aquifer is an important production factor in irrigated oases agriculture in southern Tunisia. A rise in the groundwater salinity has been observed as a consequence of increasing abstraction from the aquifer during the last few decades. All sources of contamination were investigated using hydrochemical data available from the 1980s. Water samples were taken from drains and observation wells tapping both the CT and the phreatic aquifers and analyzed with regard to chemistry, temperature, isotopes and other environmental tracers. Local salinization mechanisms are suggested, i.e. the upwelling of saline water from the underlying, confined Continental Intercalaire (CI) aquifer, as well as backflow of agricultural drainage water. At this stage, the main salt pan, the Chott el Djerid, is not a contamination source. A finite difference model was also developed to simulate groundwater flow and contaminant transport in the oases. Calibration for the period 1950-2000 was carried out in order to adjust geological and chemical system parameters. The simulation of planned extraction projects predicts a worsening of the present situation. Maintenance of the present abstraction regime will not reduce or stop the salinity increase