Interaction between wave- and tide-generated processes at the mouth of a microtidal estuary: Matanzas River, Florida (U.S.A.)

Abstract

The zone of transition between the wave-dominated open coast and tide-dominated mouth of estuaries is complicated. A time-series study of wave parameters, longshore currents and tidal parameters at the mouth of an estuary on the northeast coast of Florida has demonstrated that tidal influence on nearshore processes is modest and localized. Tidal currents are nearly undetectable less than 0.5 km from the estuary mouth along the open coast. Tidal currents reach 80 cm/s in the throat of the main ebb channel but immediately seaward of the terminal lobe of the ebb delta the tidal component is barely detectable with longshore currents predominating. Lateral flood channels adjacent to the estuary mouth show that tidal currents are significant and dominate longshore currents near low-tide stage, but are suppressed by longshore currents near high tide. Weather patterns may have an important effect on tidal processes at the estuary mouth because they control wave impingement and therefore longshore current speed and direction. Longshore currents may reinforce or suppress tidal currents, particularly in lateral flood channels.