Implications of groundwater development and seawater intrusion for sustainability of a Mediterranean coastal aquifer in Tunisia Adel Zghibi & Ali Mirchi & Lahcen Zouhri & Jean-Denis Taupin & Anis Chekirbane & Jamila Tarhouni Received: 3 February 2019 /Accepted: 1 October 2019 # Springer Nature Switzerland AG 2019 Abstract Tunisia relies extensively on coastal groundwater resources that are pumped at unsustain- able rates to support irrigated agriculture, causing groundwater drawdown and water quality problems due to seawater intrusion. It is imperative for the country to regulate future groundwater allocations and implement conservation strategies based on ro- bust hydrogeological assessments to alleviate the adverse impacts of groundwater depletion. We de- veloped a 3D transient density-dependent groundwa- ter model by coupling MODFLOW-2000 and MT3DMS to improve understanding of seawater intrusion into the Korba aquifer in Tunisia. Results indicate that groundwater overexploitation since 1965 induced 5.15 Mm 3 /year of seawater inflow while reducing submarine discharge into the sea by about 9.74 Mm 3 /year as compared to the steady state water budget in 1965. Projecting withdrawals from 2014 up to 2050 results in a slow but extensive groundwater table decline forming a cone of depres- sion 15 m below sea level. The seawater wedge under this business-as-usual scenario is expected to reach 1.8 km from the shoreline, causing significant mixing of the TDS-rich seawater in the aquifer sys- tem. The cone of depression under a 25% increase in groundwater withdrawal drops to about 20 m below sea level while the saltwater front reaches 2.5 km inland. Countering the seawater intrusion problem requires reducing groundwater pumping by 17 Mm 3 / year to push back the saltwater front along the coastline by about 25% over a 43-year period. Ap- plication of the presented generic groundwater sim- ulation framework guides developing management strategies to mitigate seawater intrusion in the Korba coastal aquifer and similar areas. Keywords Seawater intrusion . Coastal aquifer . Numerical simulation . Groundwater management . Tunisia Environ Monit Assess (2019) 191:696 https://doi.org/10.1007/s10661-019-7866-5 A. Zghibi (*) Faculty of Sciences of Tunis, UR13ES26, University of Tunis El Manar, 2092 Tunis, Tunisia e-mail: adelzguibi@yahoo.fr e-mail: adel.zghibi@fst.utm.tn A. Mirchi Department of Biosystems and Agricultural Engineering, Oklahoma State University, 111 Agricultural Hall, Stillwater, OK 74078, USA L. Zouhri AGYLE, SFR Condorcet FR CNRS 3417, Polytechnic Institute UniLaSalle Beauvais, 19 Pierre Waguet Street, 60026 Beauvais, France J.<D. Taupin Hydrosciences, UMR 5569 (IRD, CNRS, UM1, UM2), Montpellier, France A. Chekirbane Georesources Laboratory, Water Research and Technology Centre, Borj Cedria Ecopark 8, PO Box 273, 8020 Soliman, Tunisia J. Tarhouni National Institute of Agronomy, University of Carthage, 1082 Tunis, Tunisia