Geoelectric Study of the Plio-Quaternary Groundwater in the Tfal Area (Southern Gafsa, Southwestern Tunisia)

The salinization of groundwater is one of the main causes of the degradation of water quality. The water quality of the arid to semiarid regions of Tunisia depends on the captured formations and the nature of the water resources of the aquifers (renewable or ancient). In general, salinity could exceed 4 g/l. These high salinities are mainly due to the dissolution of evaporates and the lithological nature of the aquifers. However, salinities below 2 g/l (1 to 1.5 g/l) are encountered in feeding areas in carbonate and sandy structures that are protected from sources of contamination. In this paper, electrical resistivity surveying involving vertical electrical sounding and 2D profiling has been carried out to determine the distribution of salinity in the Plio-quaternary aquifer near Tfal wadi. This study allowed us to identify the origin of the salinization of the Plio-quaternary water table in the study area and to determine the extent of this salinization. The geophysical surveys, through geoelectric cross-sections and tomographic profiles, have made it possible to determine the extent of salinization, while showing the presence of Sebkha, which is the main origin of the salinization.