Résumé
Bottom friction dissipation is a key factor for wave attenuation in nearshore environments presenting complex geomorphological structures, such as rocky or coral shores. The present paper reports on a series of laboratory experiments performed in a wave flume with controlled wave conditions and seabed structures. Using the frequency-integrated short-wave analysis and classical models for bottom friction and breaking dissipation, the wave friction factor and the hydraulic roughness parameter were estimated from the experimental data. The former varies from 0.17 to 98 while the latter varies from 0 to 0.291 m. The observations reveal the combined influence of several topographical metrics, including the standard deviation, the skewness, the directionality and the effective slope of the seabed elevation. A metric-based multi-varied model for the hydraulic roughness parameter is proposed and confronted with other field data recovered on coral and rocky shores.
•A novel laboratory database for wave frictional dissipation over rough bottom.•Classical bottom friction models globally remain robust even for very large roughness.•Hydraulic roughness parameter is not solely controlled by standard deviation.•Metric-based hydraulic roughness model improves bottom friction modelling.