One important result of the St. Petersburg workshop [ Holman, et al., 1990] was the identification of high priority areas for future research. The five identified problems were: infragravity wave dynamics, wave runup, wave breaking, bottom boundary layer dynamics and sediment transport. This list has guided directions for the last five years and remains viable today, with some modification.
In general, our understanding of the barotropic flow field away from the immediate vicinity of the boundaries continues to improve with the accumulation of excellent data sets. Extension of models to cases of wave propagation and circulation of three-dimensional (complex) bathymetry (the typical case) is the next logical step. Investigations of the surface (breaking waves) and bottom boundaries remains a high priority area with a literature of laboratory-based results that has not been well tested on natural ocean beaches. Similarly, laboratory-based theories for the runup of a random wave field on a beach are only beginning to receive study on natural beaches. Finally, we are a long way from having a predictive understanding of the dynamics of sediment transport on ocean beaches.
Not mentioned in the report but of increasing importance are the nonlinear dynamics associated with feedback between the wave forcing and the beach response. Limitations in our understanding of the overall system affect not only our time horizon for system predictability, but even our knowledge of the basic phenomenology that we need to model.
A very positive note over the last five years has been the continued development and deployment of new instrumentation. A variety of tools based on acoustic and visual band signals have become available, often providing startling insights. Moreover, field experiments have developed a rigor of spatial and temporal sampling design, providing solid, statistically-defensible research results. These intensive experiments, coupled with a growing number of long term deployments, are furnishing a solid statistical base for nearshore research. One cannot help but feel excitement for the future.
Acknowledgments. The author would like to thank those who made content suggestions for paper, especially Steve Elgar, Bob Guza and Ed Thornton and Randi Miller. My students and the reviewers provided very useful editorial suggestions. Very useful funding to support this work was provided by the Office of Naval Research, Coastal Dynamics program, under grant number N00014-9411196.