Hydrogeological and Hydrogeochemical Characterization of the Aquifer System of Regueb (Central Tunisia)

In the region of Regueb, central Tunisia, agriculture represents the first socio-economic activity and has experienced a considerable extension of irrigated areas which has been accompanied by intensive exploitation of deep waters. The management of these resources is becoming increasingly difficult, and hydrogeological studies of groundwater resources are furthermore required. The multi-layered aquifer system of Regueb is yielded in sandy and sandy-clay formations intercalated by impermeable to semi-permeable Mio-Plio-Quaternary levels. It includes a superficial aquifer level exploited by surface wells and a semi-deep to deep level drilled by deep wells, especially in the south-eastern and north-eastern parts of the basin. The examination of the piezometric data from available wells allowed us to distinguish two areas with different piezometries apparently separated by an E–W edge. The northern area is restricted to the north of Regueb city and exhibits an outflow towards Sebkha Mchiguig, and the southern one is relatively wide and extends overall the basin between Regueb and Mezzouna cities. The groundwater salinity ranges between 2 and 8.5 g/L and increases to the north of the basin, however, nitrates concentrations are relatively increased in the eastern part of the basin in correlation with agricultural activity.