Due to its location, Mozambique is a country that has about 2700 Km of coast along Indian Ocean, extended from the river Rovuma to the Ponta d’Ouro. Its coastal area is largely characterized by coastal dunes that constitute aquifers of satisfactory productivity and, makes it very susceptible to exploration as potential source to water supply.

In costal aquifers, the balance fresh water – salt water is function of the flow of water to the sea. If a well field – or just a high productivity well – is settle down, the amount of water that should flow to the sea is then reduced and the position of the interface changes, that is supposed do to the penetration of seawater towards inland. If this explorations exceeded the recharge then, the balance is disrupted and the seawater penetrates slow and continually until reaching the well. If the wells are set up above masses of saltwater, can happen the ascent of the interface, being formed saline cones – up conning. Therefore, it is of great interest to establish exploration conditions so that such penetration or ascension does not reach the wells.

Is in this purpose that the present study is carried out, with the aim of determine the behaviour of the saline intrusion in the coastal region – Peninsula of Macaneta – where the development and the increase of tourist activity can drive to the significant increase of flow rates, negatively disturbing the balance of the interface fresh water – salt water.

The evaluation of the saline intrusion in the Peninsula of Macaneta is carried out on the basis of geophysical studies and hydrogeological modelling. The geophysical studies consisted of the execution of profiles of vertical electrical soundings for the determination of the transition fresh water – salt water in interface zone through the physical relationship existing between the electric resistivity of saturated soils and the salinity of the saturation water. By other hand, the modelling consisted of the analysis of the hydrogeological parameters that characterizes the system/model and the simulation of the flow and transport of groundwater of different densities (fresh water and salt water).