Dynamics and morphodynamics in sandy coastal environments. Application to the Aquitanian coast

Hélène Dupuis , Vincent Marieu , Virginie Lafon (1) , Nathalie Durand (2) , Philippe Dreuillet (3) , René Garello (4) , Jean-Marc Le Caillec (4)

1 Centro do IMAR (Universidade dos Açores)
2 IFREMER - Institut Français de Recherche pour l'Exploitation de la Mer
3 ONERA - The French Aerospace Lab [Palaiseau]
4 ITI - Département Image et Traitement Information

The Aquitanian coast (France) is representative of sandy coastal environments with long linear beaches boarding a large continental shelf and interrupted by the Gironde estuary and the Arca-chon inlet. It is a mixed-energy environment with meso-tidal and long swell influences. In order to monitor the hydro and morphodynamics of this environment, several techniques including optical and radar remote sensing are used. Firstly, SPOT optical images are used to analyse rhythmic sub-tidal and inter-tidal bar morphology and dynamics. The method is based on the semi-empirical inversion of shallow water reflectance in terms of bathymetry. The results obtained at medium spatial scale based on a set of about 20 images are summarised: the bar morphology, their time of response and preliminary analysis of physical forcing based on waverider recording. Secondly, synthetic aperture radar (SAR) is used for different dynamic aspects mainly for inlets. The PYLA 2001 campaign allowed the deployment of the polarimetric RAMSES P-band SAR (with a frequency of 448 MHz), developed by ONERA. The oceanic part of this campaign aimed both to study the capability of observing ocean surface salinity variability in the Gironde estuary and to obtain the surface currents in the Arcachon inlet. In this study, we focus on the ability of the radar images to retrieve surface currents in the Arcachon Inlet as compared with results of a two-dimensional (2D) hydrodynamic model forced by tidal effects.

Mots clés: Oceanographic techniques; SAR; Morphodynamics; bathymetry; currents; SPOT; Oceanographic techniques

Domaines: Traitement du signal et de l'image [eess.SP]

Hélène Dupuis, Vincent Marieu, Virginie Lafon, Nathalie Durand, Philippe Dreuillet, et al.. Dynamics and morphodynamics in sandy coastal environments. Application to the Aquitanian coast. EARSeL Proceedings, 2004, 3 (3), pp.289 - 297. ⟨hal-02776677⟩