The evolution of surface waves propagating across shallow coastal areas is affected by many physical processes, including those related to topography (shoaling, refraction, trapping, diffraction, reflection), nonlinear wave-wave interactions (triad and quartet resonances), and dissipation (wave breaking and bottom friction).

Refraction over the steep submarine canyons (FIGURE 1) results in strong alongshore gradients in wave height and direction (FIGURE 2). One goal of NCEX is to improve the understanding of wave refraction and diffraction on abrupt nearshore bathymetry, and to incorproate new knowledge into wave propagation models such as those for swell in southern California and those under development as part of the Navy Advanced Wave Prediction Program. The models will be tested with NCEX field observations.

In addition to refraction and diffraction, the canyon bathymetry also may result in trapping of swell and infragravity waves between the canyon heads (FIGURE 3), and reflection from the steep canyon walls. Reflection of wave energy may result in waves at Black's Beach (north of Scripps canyon), that are much larger than predicted by existing models.

Hypotheses and models for wave propagation across steep nearshore bathymetry will be tested with observations around, between, and onshore of the canyons (FIGURE 4). The observations along the 10-m depth contour also will be used to initialize models for wave propagation across the surfzone and the resulting breaking-wave driven circulation. Large-scale video imagery will also be available to examine wave propagation patterns throughout the domain.