The chemical composition of groundwater within the multilayer Jeffara aquifer and the detailed analysis of saturation indices enables identification of the origin of mineralization and hydrogeochemical processes occurring in groundwater. It has been demonstrated that groundwater is mainly characterized by a Ca–Mg–SO4–Cl water type. Geochemical pattern is controlled by the dissolution of evaporites, largely abundant in the study area and incongruent dissolution of dolomite. Gypsum, anhydrite, mirabilite and thenardite have been examined as potential sources of sulphate dissolved in groundwater. Since Jeffara groundwater is recharged by the Continental Intercalaire (CI) geothermal water, water temperature decreases from the CI to the Jeffara aquifer. Solubility of the majority of minerals is modified by this change in temperature and thus a mixing process of thermal and non-thermal waters was examined.

The continental shelf of the Gulf of Gabes is outlined, during the MIS 5c and MIS 5a onshore highstands, by the genesis of forced regressive beach ridges situated respectively at –19 m b.s.l/100 ka and –8 m b.s.l/80 ka. This area, considered as a stable domain since at least the last 130 ka (Bouaziz et al. 2003), is a particular zone for the reconstruction of the late quaternary sea-level changes in the region. Shuttle Radar Topography Mission (SRTM) data and field observations are highlighted to deduce interaction between hydrodynamic factors and antecedent topography. Variations in geomorphology were attributed to geological inheritance. Petrography and sedimentary facies of the submerged coastal ridges reveal that the palaeocoastal morphology was more agitated than today and the fluvial discharges are consistent. Actual morphologic trend deduced from different environment coasts (sandy coasts, sea cliffs and tidal flat) is marked by accumulation of marine sands and progradation.