Wave Overtopping I

Climate adaptation of coastal structures has become more important due to climate change. One of the climate adaptation measures is to reduce the wave loading before the waves reach the coastal structure. This can be achieved by constructing a low-crested structure in front of the coastal structure. To evaluate the performance of submerged low-crested structures Van Gent et al (2023) performed wave flume tests to examine wave transmission. For a submerged low-crested structure in front of a rubble mound breakwater the transmitted waves can be used as incident waves for estimates of wave overtopping, using wave overtopping expressions described in Van Gent et al (2022). However, to verify whether the system of expressions for wave transmission and wave overtopping can be applied for submerged low-crested structures in front of rubble mound breakwaters, new physical model tests have been performed. 

Wave overtopping is a key parameter on the breakwater design, since it affects the hydraulic stability, the port operativity and also generates risks to the facilities, vehicles and pedestrians. However, the maximum individual wave overtopping volume, Vmax, can be much larger than the mean wave overtopping rate, q, and it is a better variable to evaluate the direct hazards.
The prediction tools of q and Vmax are mainly based on laboratory tests, where q is registered much more easily than individual wave overtopping volumes. However, few of these studies detail the methodology to identify the number of overtopping waves and the associated individual wave overtopping volumes. 
In this study, a fully automatic detection methodology of the individual wave overtopping waves and volumes is developed using 2D physical tests. The performance of the 2-parameter Weibull distributions to estimate Vmax is analyzed here with four utility functions to weight the data, f(u).

Artificial or Engineered reefs are typically submerged structures, developed for enhancing the ecological system. Often these artificial reefs have either a complex shape inspired by biomimicry (e.g. Coastruction) or a more regular shape, designed to function as modular blocks that can be easily placed on top of each other (e.g. Reefy). In many parts of the world, application of these engineered elements on top of existing shallow reefs may be a solution to not only enhance the ecosystem but also to increase the safety level of the hinterland.
To quantify the possible effect of such artificial reefs in more shallower areas, physical model testing have been performed in which both overtopping was measured with and without the use of engineered elements.The performance of these engineered elements in relation to its submergence has been investigated and a reduction coefficient has been developed.