Directive Cadre Eau. Estimation du degré d’échange avec la mer pour les lagunes du bassin Rhône Méditerranée & Corse

In the context of the update of the inventory of water bodies of the Rhone-Mediterranean and Corsican (RM & C) basin, an assessment of pressures and impacts on the lagoons is expected during the second water management plan (2010-2015) of the Water Framework Directive (WFD). Pressures due to pollutant inputs may have a varying impact on lagoons, according to their degree of interaction with the sea. The more exchanges with the sea will be high, the more export opportunities and dilution of pollutants will be high. The more exchanges will be limited, the more pollutants will accumulate in the lagoons, making then more vulnerable to inputs. The objective of this work is to propose, for the 28 lagoons (21 transition water bodies) of RM & C Basin, an estimate of the degree of exchange with the sea, based on temperature and salinity data monitored in the lagoons and in the Mediterranean sea. The analysis of salinity data authorises to distinguish three types of lagoons, more or less confined.