Observation of Wave Transformation on Macro-tidal Rocky Platforms

Correctly predicting the transformation of ocean waves across rocky platforms has direct implications for cliff stability modelling, coastal defences and long-term coastal evolution. Wave transformation across rocky intertidal platforms is dependent on the morphological characteristics of the platform, including platform width, slope and roughness, and forcing characteristics, including wave and tide conditions. In this paper we present early observations from four field studies providing detailed measurements of wave processes across contrasting rocky platform sites with wave conditions between H-s = 0.5 m and H-s, = 1.9 m, water depths between h = 0.5 m and h = 6.8 m and variable platform morphology. Results show that the relative wave height in the surf zone H/h is generally larger than in previous studies (H/h is c. 0.6, instead of 0.3-0.5) and wave dissipation greater for sites with considerable roughness.