Wave-driven circulation over a double nearshore bar system during storm conditions.

Robin, N., Certain, R., Bouchette, F., Anthony, E.J., Meulé, S., and Aleman, N., 2014. Wave-driven circulation over a double nearshore bar system during storm conditions. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13^th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 084-089, ISSN 0749-0208. Current profiles and waves were recorded from a multi-instrumented transect over a double nearshore bar system in the Gulf of Lions, NW Mediterranean Sea (France) during storm conditions with shoreface significant wave heights of up to 3.2 m. The results constitute a preliminary analysis aimed at constraining the 3D nearshore circulation in a microtidal system. Significant time changes in the vertical distribution of nearshore velocities were observed, forced by the wind/wave conditions. Such vertical changes have been highlighted by theoretical velocity profiles in the literature, but our study demonstrates much larger variability than has hitherto been shown. Another result obtained was that the hydrodynamic pattern observed in the inner trough was distinct from that observed along the seaward flank of the inner bar. For a well-defined threshold in wave height, velocities in the trough increased abruptly and earlier, and remained strong over a longer time than those on the seaward flank. The trough thus behaves essentially as a drain for water piled against the shore. This behavior is altered by the width of the surf zone (and not only by the significant wave height), which modulates the mean current velocity. These results are a useful preliminary step in improving numerical modeling of the complex surf-zone circulation over bar-trough systems. [ABSTRACT FROM AUTHOR]