Analysis of SWAN hindcasts Wadden Sea, Oosterschelde and Slotermeer : SBW Waddenzee

Results of hindcast studies with SWAN wave model in the Amelander Zeegat, the Oosterschele estuary and the Slotermeer were analyzed to detect the cause of under-prediction of low-frequency wave energy in the coastal zone, the causes of prediction errors in the presence of the currents and the under-prediction of wave heights in depth-limited conditions. The results of this study show that the under-prediction of low-frequency energy is most likely caused by propagation effects, although the whitecapping formulation and bottom friction may also pay a role. Wave heights are over-predicted in opposing current and this is made worse by application of the adapted whitecapping formulation of WL (2007). The under-prediction of the wave heights in depth-limited situations is clearly worse for steep waves. It was also found that shallow water source terms affect the total source term balance. The under-prediction was the least by applying the surf breaking term with the breaking parameter gamma=0.8.