An Optical System for Monitoring Seabed Evolutions at a Coastal Structure

Abstract

An optical system has been designed for measuring the bed level, sand grain motions inside the soil and the presence of suspension at the toe of a coastal structure exposed to breaking waves. These measurements were conducted in the framework of the LIMAS project. We show that the soil is not strictly stable even at great depths (about 1 m). The generation of pressure differences in the soil is the main mechanism for this instability at the wall facing the waves. At the corner of the structure, the shear induced by large longitudinal velocities enhances the sediment transport and scour.

ECORS – Truc Vert 2008 : Qualification des modèles de houle et de morphodynamique

“…instrumentation de la NPS Figure 5e : structure Universités Plymouth et New South WalesLe suivi du niveau de sol et de sa stabilité a été rendu possible grâce au développement au LEGI d'un appareil de mesures par fibres optiques (figure 5a,MICHALLET et al, 2005). Ce système est constitué de plusieurs capteurs de type FOBS (Fiber Optics Backscatter Sensors).…”