Techniques d'observation et de mesure haute résolution des transferts sédimentaires dans la frange littorale

Abstract : With an increasing population in the littoral fringe and growing coastal risks, there is a pressing need for the development of effective coastal integrated monitoring strategies. This monitoring is underpinned by recurrent surveys, with techniques suited to such environment, measuring changes and allowing a better understanding of the underlying processes. To address this issue, this thesis focuses on the development of methods of survey and of quantification of morphodynamic evolution. It is centred around a very-high resolving 3D monitoring of the land-sea interface. Specifically, this research has concentrated on remote-sensing techniques : stereo-photogrammetry with a drone, terrestrial laser scanning and shallow-water multi-beam echo-sounding above the subtidal beach. For each technique, specific protocols of data gathering and data processing have been developed to compute Digital Elevation Model (DEM) and then differential DEM. This multi-sensor strategy offers a synoptic view of transfers in the sedimentary cell. The monitoring methods were applied to the sandy beach of Porsmilin (Mer d'Iroise). The results of the recurring surveys were explored to analyse the morpho-sedimentary variability at different spatial and temporal scales. The monitoring of the sedimentary cell results in the determination of closure depth (at annual scale) and in the identification of seasonal tendencies. Considering greater spatio-temporal scales, sedimentary features such as berms or beach cusps have been studied. As far as possible, each observation of topographic variations is linked to the underlying hydrodynamic forcing.
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Submitted on : Monday, December 12, 2011 - 3:20:07 PM
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Marion Jaud. Techniques d'observation et de mesure haute résolution des transferts sédimentaires dans la frange littorale. Sciences de la Terre. Université de Bretagne occidentale - Brest, 2011. Français. ⟨tel-00650953⟩

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