Detailed Morphology and Sediment Transport Processes in the Nearshore of the Fraser River Delta, British Columbia

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Hydrodynamics over a microtidal double crescentic barred beach in low energetic conditions (Leucate Beach, France)

The south part nearshore zone of the Gulf of Lions coast (Mediterranean Sea) is characterized by a double crescentic sandbar system. During the winter 2007, a campaign of intensive hydrodynamical measurements (current profiles) was realized. During this campaign, based mainly on ADCPs, the maximal recorded wave height was 1.5 m. Four events were observed; two of those had northern incidence, one with southern incidence and a last one with frontal incidence. This paper proposes 3D hydrodynamical circulation maps over this microtidal bar system. The currents described reveals rip, bed-return and longshore currents strongly influenced by the wind-waves forcing and the bathymetry. At the apex of the oblique incidence events, the longshore component is the most important. The breaker zone is only located over the inner bar. During storm waning conditions, the cross-shore currents appear over the trough of the outer bar. The hydrodynamic circulation is then compared with other observations made in the literature

Circulation in a semi enclosed bay under the influence of strong fresh water input

A high horizontal resolution 3D hydrodynamic model was applied to a semi-enclosed bay (Gulf of Fos, western Mediterranean Sea) in order to describe the specific circulation patterns driven by winds and to infer the scales of residence times. Freshwater inputs to this bay come from the Rhône river and navigation channels. Idealised simulations under typical wind forcing conditions were performed and are described in this paper. They revealed several features of the exchanges of water masses in the Gulf of Fos, in particular the intrusion of the Rhône river plume generated by south winds. During northern wind conditions, surface waters flushed out of the system. To compensate for this outflow, bottom currents transporting marine waters took the opposite direction. Residence times in the different areas of the gulf were also investigated. A realistic simulation was performed under actual conditions of Rhône river discharges, meteorological forcing and impact of the surrounding general circulation. Model outputs, mainly salinity fields, were compared to 10-day observations acquired during a multidisciplinary cruise that took place in May 2001. Model results and observations were in good agreement and showed a massive inflow of the Rhône river plume waters into the Gulf of Fos during a south wind event. Sensitivity studies showed that the salinity field was strongly dependent on the wind direction and on the local freshwater discharges

Apport de la géophysique terrestre (géo-radar, sismique réfraction) pour l’aide à la gestion du trait de côte.

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