Strategic deep aquifer valley characterization using an integrated geophysical approach (Central Tunisia, southern Mediterranean arid province)

Abstract

The joint interpretation of geophysical data provides an increasingly important integration of information capable of characterizing our subsurface planetary resources. This paper is a demonstration of a case study situated in an extremely limited water resources region, allowing the establishment of new hydrogeologic provinces. An integrated geophysical approach has been implemented to clarify the structuring, the extension, and geometry of the Miocene aquifer system located in the Sbeïtla Basin (Central Tunisia, southern Mediterranean arid province). This significant hydrogeologic basin is connected to the Tunisian North Water Transmission System to achieve sustainable drinking water supply for the Sfax region with at least 1 million residents. The seismic, gravity, and electrical methods are used together using advanced analysis (residual-regional gravity separation, electrical resistivity tomography generation from 1D vertical electrical sounding, etc.). This specific methodology allows us to reveal a new northeast–southwest strategic deep Miocene aquifer valley segmented by northwest–southeast faulting corridors. This valley can record the maximum thickness of sandstone Miocene aquifer levels called, respectively, from deep to shallow levels G1, G2, and G3 separated by two aquitards called from deep to shallow levels A1 and A2. It can be considered as a preferential target zone to carry out new deep exploration drilling.