Cappietti, L.; Sherman, D.J., and Ellis, J.T., 2013. Wave transmission and water setup behind an emergent rubblemound breakwater.
Wave transmission and water setup landward of emergent detached breakwaters play a major role in altering nearshore hydrodynamics, circulation, and morphodynamics and influencing the safety of recreational bathers. These phenomena have been extensively studied by means of small-scale laboratory experiments and numerical simulation, but field measurements have been extremely limited. In this work, wave transmission and setup were measured landward of a detached, emergent rubble-mound breakwater at Marina di Pisa, Italy. Water-surface elevations were measured with pressure transducers onshore and offshore of the breakwater. Measurements were made for 14 hours during a storm with significant wave heights up to 3.5 m and mean periods of 8.5 s. In the present work, the data were used to quantify and develop statistical relationships describing wave transmission and water setup and to evaluate the performance of empirical models of transmission and setup for emergent breakwaters. We found that the incident wave height explained (statistically) 94% of the variability in wave transmission and 96% of the variability in setup for the Marina di Pisa breakwater. There was a 99% coefficient of determination when explaining variation in setup using incident wave height and transmissivity. Of the empirical models we tested, those that best predicted observed wave transmission landward of the breakwater had root mean square (RMS) errors of 33%. The best available models to predict observed setup had RMS errors of 66%.