Design criteria for coastal defenses exposed to wave overtopping are usually assessed by mean overtopping discharges and maximum individual overtopping volumes. However, it is often difficult to give clear and precise limits of tolerable overtopping for all kinds of layouts. A few studies analyzed the relationship between wave overtopping flows and hazard levels for people on sea dikes, confirming that one single value of admissible mean discharge or individual overtopping volume is not a sufficient indicator of the hazard, but detailed characterization of flow velocities and depths is required. This work presents the results of an experimental campaign aiming at analyzing the validity of the safety limits and design criteria for overtopping discharge applied to an urbanized stretch of the Catalan coast, exposed to significant overtopping events every stormy season. The work compares different safety criteria for pedestrians. The results prove that the safety of pedestrians on a sea dike can be still guaranteed, even for overtopping volumes larger than 1,000 L/m. Sea storms characterized by deep-water wave height between 3.6 and 4.5 m lead to overtopping flow depth values larger than 1 m and flow velocities up to 20 m/s. However, pedestrian hazard is proved to be linked to the combination of overtopping flow velocity and flow depth rather than to single maximum values of one of these parameters. The use of stability curves to assess people's stability under overtopping waves is therefore advised.

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The design of the armour layer of a breakwater still allows further optimization and presents significant levels of uncertainties for selected parameters. The available analytical formulations are based on a small number of experiments and normally physical model tests are necessary in order to verify such analytical results. In this paper we consider a real storm as a benchmark to evaluate the reliability of the classical test methodology versus an innovative methodology based on synthetic storm profiles. A breakwater with a two layer cubic block armour has been used for these tests. The real storm has been scaled from a measured storm and the peak values of Hs, Tp have been used as the ‘design parameters’ for the classical methodology. The synthetic storm has been generated using the ‘Equivalent Magnitude Storm’ concept with a triangular shape. The relative damage, eroded area and depth have been used as the main evaluation parameters. The synthetic storm represents the damage evolution of the real storm well until the peak, but the damage does not increase after the peak, as in the real storm. The classical methodology by the end of the tests is returning too conservative results.@en