SHINGLE BEACH PROFILES AND WAVE KINEMATICS

Abstract

An extensive experimental project has been undertaken, in two parts, to measure both the formation of shingle beach profiles due to wave attack and the wave velocity fields using the technique of Particle Image Velocimetry (PIV). The former was achieved with moveable beach experiments carried out in the wave basin at HR Wallingford, and the latter on models in the 9.75m wave flume in The University of Edinburgh. Waves of several JONSWAP spectra, reflecting storm conditions, were allowed to impinge normally on an initial slope of 1:7, the resulting profiles were found to reach dynamic equilibrium after about 3000 wave periods. These profiles were modelled at The University of Edinburgh for the wave velocity measurements using the relatively new technique of PIV. This technique has the benefit of providing very accurate, full-field, instantaneous velocity data. In these experiments monochromatic waves were measured on smooth, impermeable beaches although the extension to multi-frequency waves on rough, permeable beaches is planned for the near future. The effect of the increased backwash component typical of these steeper beaches is dealt with in some detail.