Equilibrium beach profile model for perched beaches

A beach profile equilibrium model for perched beaches is presented. The mod el assumes that wave reflection at the seaward and leeward sides of the bre akwater is the most important process that modifies Dean's equilibrium prof ile model for non-perched beaches. The influence of wave breaking over the submerged structure is also discussed. Several laboratory data sets are use d to analyze the merit of the proposed model for describing the equilibrium condition of a perched beach. A good comparison is obtained. Results show that if the ratio between the water depth above the submerged structure, d, and the water depth at the toe of the structure, h(e), is large, d/h(e) > 0.5, only minor advance of the shoreline is achieved with the construction of a toe structure. A considerable advance is obtained for d/h(e) less that 0.1. In these situations, however, resonant effects may result in an ineff icient structure. The proposed model is used to provide an estimation for t he required sand volume and the associated beach advance for the case of na rrow breakwaters. (C) 1999 Elsevier Science B.V. All rights reserved.