Résumé
As all other in arid and semi-arid countries, Tunisia provides multiple examples of groundwater degradation due to its overexploitation. This is specially the case in the Zéramdine-Béni Hassen deep aquifer(central eaast Tunisia). This aquifer is one of the most important aquifer within Sahel of Tunisia. Its lithology is composed by clay-sandy series. Because of its tectonic complexity and the scarcity of Miocene outcrops, the hydrogeology characterization of the reservoir is not yet known. Seismic profiles interpretation highlights the existence of the Zéramdine fault corridor, the Boumerdés anticline, the Moknine, and Mahdia grabens that represent lateral boundaries for the study aquifer. The outcrop of the aquifer is located in the Zéramdine, Béni Hassen and Ain Ben Jannet regions, that represent the aquifer recharge and where two lithostratigraphic sections were realized. The piezometric study shows that the principal groundwater flow is from East to West. A secondary flow is from NW to SE. The hydrochemical study of twenty sample shows that the Zéramdine-Béni Hassen aquifer is characterized by freshwater, Na-Ca-Cl-SO4 facies, and salinity increase from west to east that is coinciding with the principal water flow direction.
In this work, an integrated methodology was developed adopting loose coupling of the groundwater flow model MODFLOW 2000 code with ArcInfo Geographic Information System to investigate hydrological processes in Zéramdine-Béni Hassen Miocene.
The groundwater model developed in this study includes an updated geometry, new estimates of parameter values and a new conceptualization of the hydrogeological system in Zéramdine Béni Hassen region and can be regarded as a useful tool for analyzing the hydrological processes and improving groundwater management practices elsewhere affected by similar geological and hydrogeological conditions.