Prediction of nearshore wave energy distribution by analysis of numerical wave model output: East Sussex coastline, UK.

Prediction of wave energy distribution in coastal areas is necessary if an assessment of the likelihood of cliff collapse is to be undertaken. Use has been made of numerical modelling to predict relative wave heights along the chalk cliff coastline of East Sussex between Brighton and Eastbourne, UK. In this study, wave modelling has been undertaken using the University of Delaware REFDIF-1 software with a 100m mesh size to predict nearshore wave heights for boundary unit wave height conditions from a range of different incident directions. The results from this wave modelling have been combined with the frequency distribution of incident waves obtained from analysis of time series of 12 years of hindcast wave data in the English Channel, obtained from the UK Meteorological Office. The resulting distribution of nearshore wave heights is presented as a surrogate for the distribution of wave energy over the 12-year period. Some concern exists about the quality of the output data, in particular of the effect of the relatively coarse bathymetry grid used for the model. Some wave focusing is evident from the model output, caused by the presence of local shoals in the model grid, leading to a ‘banding’ effect in the model output. Some suggestions are made for the improvement of the modelling scheme, including the use of finer mesh size, bathymetric smoothing and the use of a spectral model such as REFDIF-S.