Colmatage reccurent de la passe artificielle de la lagune de Fresco
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In order to understand the processes of recurrent clogging of the artificial pass of Fresco lagoon, morphological characteristics of the lagoon bottom, hydrological and chemical parameters as well as the dynamics of the sand at the lagoon pass were analyzed. Most of the Fresco lagoon area is covered by shallow depths (less than 1 m). The lagoon presents a monotonous bottom morphology with channels of 1.5 to 5 m in places. On the hydrological level, the currents on the main flow axes towards the ocean are of the order of 0.02 and 0.2 m/s on average. These currents are low, as are the measured flows. The surface waters of the lagoon and its main rivers are brackish, with salinities of 0.1 to 26 ‰, which define an east-west gradient. The bathymetric characteristics of the lagoon and the hydrological and chemical conditions highlighted do not favor strong flushing currents useful for maintaining the permanent opening of the pass. In addition, the morphology of the sandy spits of the pass reflects the strong influence of oceanic conditions. They dominate the characteristics of continental inflows and regularly promote silting up and clogging of the pass. This clogging is therefore governed by the hydrological and sedimentary processes between the lagoon and marine environments separated by a barrier cordon.