Storm-Driven Hydrodynamic and Sedimentological Impacts to an Engineered Coast

Abstract

Ellis, J.T. and Cappietti, L., 2013. Storm-driven hydrodynamic and sedimentological impacts to an engineered coast.We replicated a breakwater, seawall, and artificial gravel beach from Marina di Pisa, Italy in a 1:40 scale-model. The model was tested in a wave-current flume that is 50 m long, 0.8 meters wide and high, and located at the University of Florence. The gravel beach, berm, and breakwater models were constructed based upon in situ beach surveys. The laboratory quartz boulder beach and breakwater D50 approximated 3.0 mm and 3.6 cm, respectively. The laboratory hydrodynamics aimed to simulate a portion of storm measured at a local wave buoy during an event in October 2003 that lasted 54 hours. Ten wave runs were conducted with durations ranging from 9.5 - 43 min with programmed peak wave periods of 1.4 - 2.1 s and significant wave heights of 9.6 - 17.5 cm. Seven wave gauges were distributed along the wave flume, two adjacent to wave maker, three just offshore the breakwater, and two just onshore of the breakwater. The clear glass side of the flume was delineated to capture millimeter scale changes of beach and berm morphology. Wave transmission (Kt) values calculated using field-based measurements ranged from 0.33–0.52, suggesting that between 11–27% of the offshore energy is transmitted through the breakwater. In the laboratory simulation of the storm, the modeled Kt values under-predicted measured Kt values by 1–16% and the berm migrated onshore to the upper shoreface and flattened the overall beach profile.