Assessing Shoreline Displacements Caused by Storms and Seasonal Changes in Wave Activity

An approach to assessing changes in the shoreline position under the impact of waves on a sandy shore is proposed. The model determines the volumes of material arriving at the beach or leaving for the subaqueous slope during a given period of time. The input parameters are the mean sand size, the beach slope, and the chronogram of wave heights, periods, and directions in deep water. The model is calibrated based on published data from experiments in wave channels under the impact of waves with constant parameters on an initially flat coastal slope. Published data from the US Atlantic coast were also used. The model was tested using observational data on a section of the eastern Baltic coast with a developed system of nearshore bars, where changes in the average values of coastline from –6 to 10 m were recorded. Calculations based on ERA5 wave reanalysis data revealed cyclical shifts of the shoreline with a period of about 1 year, caused by seasonal fluctuations in wave activity. The root mean square error of the calculated shoreline shifts is estimated at 4.0 m.