Wave packets approaching a cliff from the ocean are known to amplify significantly at the cliff wall, known as runup amplification. This is caused by a combination of reflection, constructive interference, and nonlinear effects such as dispersion (Carbone et al., 2013; Viotti et al., 2014). Furthermore, strong variations in depth enhance the amplification of waves (Viotti and Dias, 2014). In realistic settings, the bathymetry profile is complicated; however, in general, it becomes shallower nearer the cliff wall. Quantifying the wave amplification in these settings gives understanding of the wave power produced and pressures generated on the cliff and coastal structures.
The influence of the bathymetry on the wave conditions is evident. Shoaling effects enhance wave breaking, observed in the simulations. The runup of breaking or non-breaking waves is a consideration for the types of overtopping flow that may be observed at a cliff, e.g., fast bore developing form the collapsing surge (non-breaking) and spray sheets (breaking) (Hansom et al., 2008). We consider criteria for the wave breaking during runup over a varying bathymetry.