Identifying the origin of groundwater salinisation in the Sidi El Hani basin (central-eastern Tunisia) - Ecole Nationale du Génie de l'Eau et de l'Environnement de Strasbourg Accéder directement au contenu
Article Dans Une Revue Journal of African Earth Sciences Année : 2018

Identifying the origin of groundwater salinisation in the Sidi El Hani basin (central-eastern Tunisia)

M'Nassri Soumaia
  • Fonction : Auteur
Dridi Lotfi
  • Fonction : Auteur
Hachicha Mohamed
  • Fonction : Auteur
Majdoub Rajouene
  • Fonction : Auteur

Résumé

In the Sidi El Hani basin, located in central-eastern Tunisia, a shallow aquifer is the main water source for agricultural practice. However, in the last few decades, it has undergone saline pollution. In this context, this study is carried out to identify the origin of the dissolved species and the processes involved in the increase of groundwater salinisation using hydrochemical tools and geochemical modelling with PHREEQC. To achieve this objective, water analysis was performed on 49 samples collected from 46 shallow wells and 3 observation wells during March and April 2015. The results indicate that for the samples located near the Sabkha Sidi El Hani, the dominant facies of the groundwater is sodium chloride (Na-Cl). The water samples are characterized by high salinity exceeding 6 g.L−1. However, in the centre of the basin, the water samples are a mixed type (Cl-Na-SO4-Ca-Mg). Our results show that salinisation of the groundwater was due to the dissolution of halite, cation exchange, and the precipitation of carbonate minerals such as calcite and dolomite coupled with the dissolution of gypsum, and evaporation. Intensive irrigation in the area leading leaching of salts from the surface soils to deep soil layers are additional factors. This soil leaching is the major process that accounts for salinisation of water and soil; it leads to the accumulation of a bitter brine solution after the precipitation of evaporite minerals.
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Dates et versions

hal-02977068 , version 1 (23-10-2020)

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Citer

M'Nassri Soumaia, Dridi Lotfi, Yann Lucas, Gerhard Schafer, Hachicha Mohamed, et al.. Identifying the origin of groundwater salinisation in the Sidi El Hani basin (central-eastern Tunisia). Journal of African Earth Sciences, 2018, 147, pp.443-449. ⟨10.1016/j.jafrearsci.2018.07.004⟩. ⟨hal-02977068⟩
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