Analysis of wave penetration into the Eastern Wadden Sea

An analysis has been performed of the SWAN model results obtained in a hindcast of the 8/9 November 2007 in the Eastern Wadden Sea. The analysis was aimed at deteremining the possible causes of the observed underprection by SWAN of low-frequency wind waves in the Eastern Wadden Sea. Firstly, a literature survey was carried out to find out which relevant information is available on this subject. Secondly, an analysis was made of hindcast results of the storm of 9 November 2007 in the Eastern Wadden Sea wish an emphasis on the penetration of low-frequency wave energy. Thirdly, a sensitive analysis was carried out to the effect of variations in boundary conditions, numerical and physical settings on the penetration of low-frequency wave components in the Eastern Wadden Sea. The results of the study point to a strong role of refraction, bottom friction and surf breaking action on low-frequency as well as reducing bottom friction and applying frequency-dependent breaking improve the predicted amount of low-frequency wave energy near the mainland coast. The role of diffraction, as modelled in SWAN, is found to be very weak. Since measured data are only available for one storm, it is strongly recommended to analyse the penetration of low-frequency wave energy in other similar areas.