On the modification of edge waves by longshore currents

On natural, barred beaches edge waves with frequencies within the range of the wind-wave frequencies are found to be trapped on the bar. For edge waves travelling in the direction of a longshore current, the onset of trapping is shifted to lower frequencies. The frequency range where the waves are trapped on the bar becomes greater and the waves in this range exhibit larger amplitudes offshore than at the shoreline. Furthermore, the most distant offshore antinode trapped on a bar increases its amplitude under the influence of longshore currents for edge waves travelling with the current. The objective of this note is to elucidate some new aspects of the impact of a natural seabed profile in the presence of longshore current.