A case study of wave height variations due to currents in a tidal entrance

A case study is presented of the effects of tidal currents on the wave heights in a tidal entrance, viz. the Oosterschelde estuary in the Netherlands. Observations of the variation of wave height with tidal elevation during a tidal cycle show a hysteresis. In order to investigate this phenomenon, calculations have been made of wave height changes due to refraction by non-uniform depths and currents, including the occurrence of wave breaking on the shoals in the estuary delta. The calculated wave height variation with tide elevation is found to have a current-induced hysteresis similar to the observed one.