Wavetide

Wavetide is a coastal marine phenomenon defined as periodic amplification of nearshore waves that occurs in association with certain phases of the tidal cycle. It describes episodes when wave heights and energy near the coast exceed expectations from wind and swell alone, producing pronounced waves that can influence coastal zones and nearshore activities.

The term is used by researchers and coastal engineers to describe a pattern driven by the interaction of incoming swells, local bathymetry, and tidal currents. Wavetide is not a separate tide, but a modulation of wave activity that emerges when tidal dynamics affect the propagation and concentration of wave energy along a coastline.

Mechanism: Long-period swells refract toward the shore and shoal as water depth decreases. When tidal currents are strong, they interact with the wave field, altering phase speed and direction. In areas with particular shelf geometries or irregular bathymetry—such as concave bays or submarine canyons—the energy can become temporarily concentrated, leading to higher crest heights and extended wave trains during specific points in the tide.

Occurrence: Wavetide events are most commonly reported on mid-latitude coasts with moderate tidal ranges and complex underwater topography. The intensity and timing of wavetide episodes depend on seasonal wind patterns, storm tracks, and regional bathymetric features.

Impacts: Wavetide can increase nearshore run-up, influence coastal erosion rates, and pose hazards to vessels operating in restricted waters. In surfing communities, wavetide conditions may be anticipated for large-wave sessions, though safety considerations remain.

Measurement and modeling: Observations come from coastal wave buoys, tide gauges, and radar. Forecasts combine tide models with spectral wave models to predict peak wavetide events and associated coastal impacts. See also tide, swell, and coastal engineering.