Unravelling deep aquifer architecture in a Mediterranean region: Gravity‐based insights from El Alem–Sousse transect (transition zone between the Atlassic and Pelagic domains)

Abstract Groundwater management in arid and semi‐arid regions, particularly around the Mediterranean Sea, poses significant challenges in terms of exploration, exploitation and sustainability. This study focuses on understanding the structural and sedimentary variations on the Sahel domain in Eastern Tunisia, Western Mediterranean province. Groundwater resources are predominantly tapped through shallow and deep wells within syncline structures filled with Neogene sediments, predominantly siliciclastic deposits but a clear delimitation of aquifers is lacking. The gravity method combined with seismic interpretation, petroleum and water well description is employed to explore the subsurface geology, aiming to enhance comprehension of the basins and sub‐basins structure. The latter is a key component to recognizing water recharge and discharge pathways and to develop effective and long‐term groundwater exploration strategies. First, the residual gravity field is produced. Derivative maps, an Euler deconvolution solution map and a 2D gravity inversion model are subsequently generated to delineate different anomalies and to estimate the depth to basement and subsurface density contrasts. The different maps and the 2D gravity inversion models show that: (1) The Sisseb‐El Alem and Sousse regions are separated by a deep NE–SW positive anomaly, related to a basin structure that can reach up to 3 km depth; (2) the Sisseb‐El Alem region is composed of many elongated sub‐basins with N–S, E–W and NE–SW directions (local negative residual anomalies) separated by NW–SE and E–W structures. Finally, the proposed method provides a valuable basis for better management of hydrogeological exploitation.