Extended equilibrium beach profiles

The idea of an equilibrium beach profile has been a useful concept in both theoretical and practical coastal engineering studies. In essence, the subject has thus far evolved to a choice of shape functions, which are described by a small set of parameters. Additional efforts have attempted to relate these parameters to more fundamental quantities, such as average grain size of the bottom sediment, wave environment, geometric aspects of the beach, and the like. This approach has a long history and can rightly claim a certain level of success. However, the usual collections of shape functions are well-known to have difficulties very near the shoreline, let alone on the nearshore portion of the beach. This study extends the equilibrium profile up to and somewhat past the shoreline. Three shape functions are used in conjunction with a Taylor expansion for the nearshore and above water portions of the profile. A nonlinear fitting technique is applied to estimate the model's best parameter values. Moreover, reduced versions of the proposed models can be employed for prediction based only on parameters related to sediment characteristics or wave conditions and geometry of the visible beach. The approach is compared with data from the East Coast of Australia, the East Coast of North America and the South Shore of the Mediterranean Sea.