This research work deals with the supplying and functioning conditions of the karstic brackish springs of Port Miou and the Bestouan, both the main outlets of Port Miou's karstic littoral aquifer. The chosen methodology is a multiple criteria approach to hydrology, hydrogeology, speleomorphometry, as well as to the paleographic structure and inheritance of the whole karstic system. A year and a half has been necessary to process to the hydrometric monitoring of the submarine springs - a time of drought that has affected the entire lower Provence. The analysis of the mixing mecanisms between fresh water and sea water in the karstic aquifer shows that the contamination of the springs sustainably takes place through deep sea water intrusions in the network. The study of the floods reveals that the karstic network's increase of the water head doesn't lower the amount of sea water that is part of the mixing. Each rise in the water level is characterized by an additional supplying of fresh water into the karst conduit which contributes to cause a drop in the spring water's salinity and temperature. The reappraisal of the water balance of the main Jurassico-Cretaceous massifs in the region of Marseille reveals the potential existence of important deep karstic flows from which Port Miou's aquifer could benefit. It seems justified to suggest that this system is structured along a karstification spreading deeply and vastly, and today partly drowned into the sea. The genesis and the organization of that deep and vast karst can be explained by the Messinian model of karstification recently adopted to the development of many perimediteranean karstic aquifers.
