[tel-00814446] Etude de la dispersion horizontale en zone littorale sous l'effet de la circulation tridimensionnelle forcée par les vagues - Application à la baie de Saint Jean de Luz - Ciboure et au littoral de Guéthary-Bidart

This work aimed at providing a better understanding of nearshore circulation and dispersion processes under the effect of waves. An operational numerical modeling tool was developed, based on the spectral wave model WAVEWATCH III and the 3-D hydrodynamical model MOHID Water. The MOHID implementation was extended to the glm2z approach for 3-D wave-current interactions. Theoretical developments leading to glm2z equations are gathered and detailed in the present work. The numerical implementation of glm2z equations is described. The model is validated in academic cases, in which the obtained solution is shown to be consistent with that provided by reference numerical models. Both numerical modeling and in situ measurements are then used to study two nearshore environments, located on the French South Atlantic coast. These complex areas combine a significant effect of waves on dynamics and remarkable salinity stratification. Comparison of 3-D model results with field data are encouraging and offers interesting insights for current and salinity profile variability. Dynamics of a semi-enclosed estuarine bay is first studied. Modeling results suggest that waves may have a significant impact on river plumes, leading to a reduction of the global bay flushing during a raining event. The second study site allows the investigation of the intense circulation generated by waves over a ridge and runnel system, and the dispersion of freshwaters introduced in the surfzone by a small river. Finally, this work provides a 3-D numerical modeling tool for the study of the circulation and related transports under the effects of nearshore forcings.



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