Hydrodynamics of the Toliara Reef Lagoon (Madagascar): Example of a Lagoon Influenced by Waves and Tides

Abstract

ABSTRACT Chevalier; C.; Devenon, J.-L.; Rougier, G., and Blanchot, J., 2015. Hydrodynamics of the Toliara reef lagoon (Madagascar): Example of a lagoon influenced by waves and tides. In meso-tidal lagoons, the coral reef barrier can be temporarily submerged at high tide and partially exposed at low tide, which causes highly specific lagoon dynamics. To understand those dynamics, three field-measurement campaigns were conducted in the Toliara Lagoon (Madagascar), where the tide and the waves increase that effect. The method combined measurements taken from fixed moorings and measurements from a small, moving, inflatable boat along the transects through the reef passages. A tidal analysis methodology adapted to this lagoon was used to reconstitute the currents through the passages and to determine the spatial and temporal current variability. Then, the lagoon water dynamics were studied. The tidal dynamics of the lagoon appear to depend significantly on flows through the passages, although they were also af...