In-situ Measurements of Wave Impact Pressure on a Composite Breakwater: Preliminary Results

Larroque, B.; Arnould P.; Luthon F.; Poncet, P.A.; Rahali, A., and Abadie, S., 2018. In-situ measurements of wave impact pressure on a composite breakwater: preliminary results. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1086–1090. Coconut Creek (Florida), ISSN 0749-0208.A detached horizontally composite breakwater protecting the Saint Jean de Luz bay (French Basque Coast, Bay of Biscay, France) has been equipped with two pressure sensors displayed vertically onto the vertical wall. The two sensors recorded wave impact pressure in ten minute burst each hour at 10 kHz. In parallel, incoming waves were also recorded about 1 km off the structure with a directional wave buoy giving access to spectral wave parameters as well as raw data. Finally water level, wind magnitude and direction were also acquired. The whole dataset covers winter 2015–2016 from January to March.The results show first the statistical distribution of the measured parameters confirming preceding similar studies in which significantly lower impact pressure values were obtained compared to physical experiments or numerical simulations. A linear multivariate model has then been adjusted showing the overwhelming influence of wave heights to explain maximum pressure variability, followed by water level. Nevertheless this result has still to be confirmed for data reduced to impulsive impacts. Finally, interesting events supposedly corresponding to, or approaching flip-through impact type, have been identified and need further investigations.