Résumé
Mangrove coasts are highly dynamic: the coastal landscape evolves according to sedimentary inputs, which mass along the coast to form mud banks covering hundreds of hectares at low tide. The appearance and disappearance of mangrove forests, observed over several decades from satellite images, appear to be strongly correlated with erosion or mud accretion processes. These observations not only raise questions about the ability of mangrove forests to survive in a context of climatic and oceanic change, they also call into question the ability of human activities to adapt to these coastlines. By studying the evolution of mangrove forests at the land-sea interface, would it not be possible to gain a better understanding of the physical processes that constantly reshape muddy coasts and anticipate changes? The coasts of the Guiana plateau, under the influence of the Amazonian sediment dispersion system, are a pilot region for tackling these issues.In French Guiana, spatial observation based on time series of satellite images of changes in the coastal landscape is becoming operational to map fluctuations in the sea-mangrove coastline and the extension of mud banks. However, data and models are still lacking to quantify the impact of oceanic processes, particularly swell regimes, on the transformation, whether erosion or silting, of Guyana's 320 km of coastline. In particular, the attenuation of ocean swell energy by mud banks has only been quantified and modelled to a limited extent due to the difficulties of taking measurements on this muddy and changing interface.