Wave transformation on a microtidal barred beach (Se `te, France) Raphae ¨l Certain a, * , Samuel Meule ´ b,1 , Vincent Rey c,2 , Christel Pinazo b,1 a Laboratoire d’Etudes des Ge ´o-Environnements Marins, Universite ´ de Perpignan, 52 av. P Alduy, 66860 Perpignan, France b Laboratoire d’Oce ´anologie et de Bio-Ge ´ochimie, Centre d’Oce ´anologie de Marseille, UMR 6535, Universite ´ de La Me ´diterrane ´e, Rue de la batterie des Lions, 13000 Marseille, France c LSEET-LEPI, UMR-6017 du CNRS, Universite ´ du Sud Toulon-Var, BP 20132, F-83957, La Garde Cedex, France Received 27 September 2004; accepted 2 June 2005 Available online 15 September 2005 Abstract An instrumented field study of the cross-shore evolution of incident waves was conducted on the shoreface of a gentle sloping microtidal barred-beach (Se `te, France). A spectral analysis of typical hydrodynamic conditions (storm, waning storm and fair-weather) was performed from a series of pressure sensor data and synchronized horizontal velocities and pressure data. Results highlight the role of sedimentary bars in the dissipation and the spectral redistribution of incident energy. At the approach to the coast, the bars act like regulators of energy arriving at the shore and non-linear energy transfers are observed from the gravity to infragravity domain, during breaking or non-breaking situations. Consequently, the ratio of infragravity to gravity wave spectral energy density increases shoreward as significant wave height decreases. The study of incident wave reflection shows that during storm conditions, no significant wave reflection is observed and the beach can be classified as dissipative. During fair-weather conditions, a significant reflection from the beachface is observed but the bars do not play any role in this reflection. D 2005 Elsevier B.V. All rights reserved. Keywords: Waves; Infragravity waves; Spectral analysis; Energy transfer; Wave reflection; Nearshore bars 1. Introduction The nearshore evolution of incident waves has drawn interest for the understanding of the role of linear and non-linear processes in the wave energy transfer in the breaking and the surf zones. For regular slopes, wave energy decreases and infragravity waves behaviour are quite well understood and modelled. Beaches are then classified as dissipative, intermediate or reflective according to the beach slope and the incident wave significant energy (Wright and Short, 1984). For barred beaches, such as the beach of Se `te, the wave transformation is more complex, with break- ing preferentially over the bars, and deshoaling behind 0924-7963/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jmarsys.2005.06.001 * Corresponding author. Tel.: +33 4 68 66 17 45. E-mail addresses: certain@univ-perp.fr (R. Certain), samuel.meule@com.univ-mrs.fr (S. Meule ´), vincent.rey@lseet.univ-tln.fr (V. Rey). 1 Tel.: +33 4 91 04 16 45. 2 Tel.: +33 494 14 20 69. Journal of Marine Systems 38 (2005) 19 – 34 www.elsevier.com/locate/jmarsys