Gravel beach profile response allowing for bimodal sea states

The south coast of the UK is identified as a location where significant wave swell components are present within the regional wave climate. During the winters of 2006 and 2014, several sites along the south coast of the UK were subject to significant damages where flood events were recorded. These sea–states were characterised by having a double–peaked wave spectra, observing a connection between wave spectrum shape and beach response. A 2D physical model study was carried out to investigate the effect of gravel beach profile response under wave spectra characterised by swell and wind wave periods in various combinations. The physical model results have shown the effect of bimodal wave spectrum on the beach crest erosion and have been compared with the parametric model of SHINGLE and the numerical model XBeach-G. Based on this 2D physical model study a new parametric model, Shingle–B, has been derived and an online tool has been developed and made available on the website for the National Network of Regional Coastal Monitoring Programmes of England. This new tool has been validated with two sites in the South of England where field data of both waves and profiles was available.