A numerical model that treats density-dependent variably saturated flow and miscible salt transport is used to investigate the occurrence of seawater intrusion in Cop Bon coastal plain of north-eastern Tunisia. We examine the effects of and interplay between pumping, artificial recharge, soil/aquifer properties, and the unsaturated zone. This study examines on approach for planning groundwater development in coastal aquifers. The seawater intrusion is controlled through a series of barrier extraction wells. The multi-objective management problem is cost as a non-linear, no convex combinatorial model and is solved using a coupled simulation-optimisation approach. A density-dependent groundwater flow and transport model, Ground Water Vistas is used for simulating the dynamics of seawater intrusion. The Simulated Annealing algorithm is used for solving the optimisation problem. The data processing steps undertaken in this study are briefly de-scribed, and a critical assessment is given of the data avail-ability and of the requirements for successful monitoring and modelling of seawater intrusion risks in heavily exploited coastal aquifers such as those found in the semi-arid regions of the Mediterranean basin. An idea of the extent of over-exploitation of the Grorribalia and Oriental Coastal aquifers is obtained by examining the pumping and rainfall/infiltration data, and the simulation results support ground-water pumping as the mechanism for and seawater intrusion as the origin of the salt contamination observed in the soils and subsurface waters of the Grombalia and Oriental Coastal aquifers The physical characteristics of the coastal aquifer of the Cop Bon in the North of Tunisia, were determined by using GMS software MODFLOW Code. This was helped in the quantification of the aquifer inflows and discharges as well as to the aquifer sustainability management, especially in the interaction between the Upper and Lower Aquifers for the area. The utility of the study is demonstrated through a trade-off curve between prioritising groundwater development and controlling seawater intrusion at desired levels.