This project will supplement a collaborative effort with the Naval Postgraduate School and the University of Delaware as part of a European field experiment to examine through observations and numerical modeling the three dimensional nearshore flow dynamics at the turbulent, incident wave, infragravity wave, very low frequency and mean times scales on a beach with large bathymetric variability. The field experiment is planned for the spring of 2008 and will be conducted at Truc Vert Beach on the Atlantic coast near Bordeaux, France. This beach features an energetic wave climate, strong tidal modulation, and a typically complex planform with crescentic bars, rip channels and an inter-tidal zone with ridges and runnels. State of the art numerical modeling will be used to design and optimize the in-situ field arrays composed of coherent co-located pressure and velocity sensors, pressure sensors, ADCP?s, and a bottom boundary layer instruments prior to the field experiment. The in-situ instruments are very difficult to move after the initial deployment and therefore pre-experiment computations are essential. Numerical modeling will also be used during the field experiment to optimize the deployment of surf zone drifters to map the surface velocity field of the rip current systems. To that end the numerical model will use a mixed Lagrangian/Eulerian description of the near surface velocity field. These computations will give insight in the optimal location of the initial drifter deployments to capture nearshore circulations that are of interest to our research. These optimal locations are subject to the (changing) wave and tidal conditions which can be easily assessed with the numerical modeling.
Broader Impacts: The impacts of the proposed research include predicting location, persistence, and strength of rip currents for swimmer safety, modeling dispersion of sediment and pollutants (both from point sources such as storm drain discharge and from distributed sources such as agricultural runoff) and anticipating shore line and dune erosion. The beach planform at Truc Vert is more complex than any that has been studied up to date in a comprehensive fashion. As such it poses a formidable challenge in the modeling of the three dimensional hydrodynamic response during energetic wave conditions and the data set to be obtained would be unique among available data sets anywhere in the world. Finally, participation in the field experiment will give first hand experience to a numerical modeler with the acquired measurement data allowing for future model-data comparisons.
