An Engineering Method For The Preliminary Functional Design Of Perched Beaches. Theoretical Approach

Perched beaches are an attractive nourishment design alternative especially when either the site conditions or the characteristics of both the native and the borrow sands lead to a non-intersecting profile. The observation and suggestion of the use of this type of coastal defense scheme dates back to the 1960's, as well as the international experience in its construction. However, in spite of its use and the field and laboratory studies performed to-date, no design engineering guidance is available to support its design. Key dimensionless parameters that will be able to explain the performance of perched beaches have been identified, linking basic design variables such as: the wave height and period, the crest width and height, the depth at the toe of the sill, and the sand settling velocity. An engineering 4-step conceptual design method has been anticipated. This work will be expanded by systematic mobile-bed physical model tests - to be performed in a 36 x 3 x 1.5 m wave flume -, with the goal of producing engineering preliminary functional design guidelines of perched beaches based on the key dimensionless parameters herein identified.