Publications des scientifiques de l'IRD

Anthony E. J., Dolique Franck, Gardel A., Gratiot Nicolas, Proisy Christophe, Polidori L. (2008). Nearshore intertidal topography and topographic-forcing mechanisms of an Amazon-derived mud bank in French Guiana. Continental Shelf Research, 28 (6), p. 813-822. ISSN 0278-4343.

Titre du document
Nearshore intertidal topography and topographic-forcing mechanisms of an Amazon-derived mud bank in French Guiana
Année de publication
2008
Type de document
Article référencé dans le Web of Science WOS:000254691800009
Auteurs
Anthony E. J., Dolique Franck, Gardel A., Gratiot Nicolas, Proisy Christophe, Polidori L.
Source
Continental Shelf Research, 2008, 28 (6), p. 813-822 ISSN 0278-4343
The intertidal topography in the vicinity of the contact zone between a longshore-migrating Amazon-derived mud bank and the muddy terrestrial shoreline in French Guiana was defined from a combination of satellite-based SPOT images, airborne lidar data and high-resolution total station ground surveying of a 75,000 in 2 plot. The three approaches, at different scales, were carried out at different periods. Digital elevation models generated from these three techniques, however, converge in highlighting the topographic micro-scale (centimetre-scale) variability of the mud bank surface while showing meso- to macro-scale features that reflect the dominance of wave activity in mud bank mobilization and attachment to the terrestrial shoreline. These features are bar-like longshore forms that develop in the intertidal zone from the shoreward drift of gel-like mud that accompanies wave damping. The features progressively become consolidated through mud drying out associated with the formation of cracks that are important in mangrove colonization and ecological changes. Fluid-mud accumulations formed from high concentrations of mud trapped in the troughs behind these linear bar forms generate flat featureless surfaces that tend to mask topographic heterogeneity of the mud bank surface. Dewatering of these lower zones by progressive mud consolidation complements tidal water discharge in providing a mechanism for the formation of the numerous channels that dissect the linear bar features, especially in the upper intertidal contact zone with the terrestrial shoreline. This dissection in the upper intertidal zone generates an intricate topography that replaces the original linear bar forms. The innermost bar forms a 'suture' zone with the terrestrial shoreline. Reworking of this bar by high-energy waves may lead to mud dispersal over old terrestrial mangrove substrates, resulting in stifling of mangrove pneumatophores. Mud reworking at the narrow trailing edge of the Mud bank in the subtidal and lower intertidal zones leaves behind a flat bed that will eventually be completely croded by waves in the course of mud bank migration.
Plan de classement
Géologie et formations superficielles [064] ; Etudes, transformation, conservation du milieu naturel [082]
Description Géographique
GUYANE FRANCAISE
Localisation
Fonds IRD [F B010042513]
Identifiant IRD
fdi:010042513
Contact