Beach Cusps - Field Studies

Field Studies

In recent years, there has been considerable debate about whether beach cusp formation is associated with the presence of standing edge waves (standing edge wave theory), results from self-organizing feedback between changing topography and swash motion (self-organization theory) or is attributable to a number of other less popular mechanisms.

The National Centre of Scientific Research in France, collected a large amount of data from laboratory experiments and field studies, published over the last 50 years to test the predictions of the two main cusp forming hypotheses. These analyses, using more data than previous attempts, confirm that there is a possible link between cusp development and both edge waves and swash-sediment feedback, and that it is not possible to produce conclusive support for one theory above the other with the simple measurements that have been made previously.

The Naval Research Laboratory, the corporate research laboratory for the United States Navy and Marine Corps carried out nearly nine years of video imagery from Duck, North Carolina to determine the timing of cusp formation (to within half a day) and the distances separating consecutive cusp horns (to within half a metre). Supplementary data provided by nearshore instrumentation and surveying vehicles was used to document the environmental conditions during cusp development.

These extensive observations conclusively demonstrate that cusps at this location develop, following storms during the transition from high energy to low energy wave conditions as the wave angle approaches normal incidence. A peculiar suggestion of historisis within the cusp spacing time series was observed and may suggest that existing theories of cusp formation need to be reformulated.