LOW FREQUENCY WAVES IN INTERMEDIATE WATER DEPTHS

Abstract

This paper is concerned with calculations and field measurements of low frequency or infragravity waves associated with wave grouping (frequencies in the range of 0.005 to 0.04 Hertz). These waves have periods in excess of wind generated waves and they are assuming particular importance now due to the effect they are thought to have on sediment transport in and near the surf zone. However, the impetus for the work described here originated from a need to quantify the magnitude of these waves in intermediate depths typical of harbour entrances: it being generally accepted that long period waves excite harbour resonances and moored ship movements, leading to berth downtime.