SUSPENDED SAND CONCENTRATION EVENTS DUE TO SHOALED WAVES OVER A FLAT BED

A field experiment was conducted in July 1988 near Cape Canaveral, Flo rida, to study the interactions between waves and suspended sand in sh allow water. Measurements were made of pressure, the horizontal compon ents of water velocity, and suspended sediment concentration over a fl at sea bed just seaward of the surf zone. These observations of suspen ded sand concentration reveal intermittent near bed suspension events. Using an ensemble averaging technique, the temporal structure of the nearbed suspended sediment concentration is characterized. Events resu lting in on-shore transport are found to have distinctly different tem poral structure than events causing off-shore transport. The temporal structure of the concentration is consistent with a sediment entrainme nt model in which sediment is entrained primarily during the on-shore phase of the wave motion.