Short-Term Sediment Transport at a Backbarrier Beach

Abstract

This article defines short-term (tidal cycle) sediment-transport patterns at a backbarrier beach based on detailed field studies. Fieldwork was planned to record nonstorm, spring tide conditions that enable the definition of background sediment dynamics at the study area. The experiment was set at two beach morphologies: beach face and sandbank. Current meters were deployed at both sites. Fluorescent tracer techniques were applied to determine rates and direction of transport. Topographic surveys and sediment sampling were undertaken. During the experiment, limited tracer displacement and small morphological changes occurred. The low magnitude changes are representative of predominant, low-energy hydrodynamic conditions. Sediment transport was primarily longshore orientated and dependent on the velocity of tidal currents. Tidal currents had the potential for sediment transport only during a short period of the tidal cycle and had higher velocities during ebb, which results in a net sediment transport orientated towards the nearby inlet. It is suggested that there is dependence on sediment transport rate at the study site and on the variability of tidal currents, which are greatly influenced by the distance to, and conditions of, the nearby Anca˜o Inlet.