Contribution of integrated geophysical data to the study of the relationship between the Sfax and Regueb aquifers in the Tunisian Sahel, Eastern Tunisian Foreland Basin (Mediterranean arid region)

Groundwater is the main water resource in Tunisia, especially in the Tunisian Sahel (arid region of the Mediterranean). The increasing scarcity requires understanding the interactions between the Sfax deep aquifer of the Upper Miocene and the Regueb aquifer of the same age. This article studies the hydrogeophysical relationship between these two deep aquifers. The method involves seismic, gravity, and piezometric data collected during high and low water table periods to better understand the hydrogeological connection, groundwater flow mechanisms, and recharge zones. Lithostratigraphic correlation of NW-SE direction shows the thickness of geological formations across the study area, with the Regueb aquifer exceeding 800 meters in depth and the Sfax aquifer over 1000 meters, indicating a strong hydrogeological connection. Seismic reflection data suggest that the two aquifers are tectonically shaped by a Cretaceous heritage. Gravity maps such as Bouguer anomaly, MGH, Euler Deconvolution, TILT, and a 3D gravity model were created to delineate the structurally controlled boundary between the two deep aquifers and to highlight the subsurface structures, fault networks with their depths, and their directions. Finally, this integrated study for the first time reveals a structure that controls the boundary and flow between the deep aquifers of Regueb and Sfax.