Accession Number : ADA218196

Title :   Modelling of Nearshore Sediment Transport.

Descriptive Note : Rept. for 1 Sep 86-30 Dec 89.

Corporate Author : FLORIDA UNIV GAINESVILLE DEPT OF COASTAL AND OCEANOGRAPHIC ENGINEERING

Report Date : 30 DEC 1989

Pagination or Media Count : 89

Abstract : Field observations of vertical profiles of suspended sediment concentration and point measurements of water velocity were obtained in a nearshore region on Prince Edward Island. Suspended sediment concentration profiles were measured with approximately 0.8 seconds temporal resolution and 0.5 cm minimum vertical spatial resolution using a 3 Mhz Acoustic Concentration Meter. During post-storm, mild wave conditions the suspension of sand seaward of the surf zone was found to be intermittent. The suspended sediment concentration is clearly unsteady, and dominant by events. A field experiment was conducted in summer, 1988, at Cape Canaveral, as a component of this project. Detailed measurements of wave/current forcing and the local sediment response were obtained over a two week period. The physical processes responsible for the correlation between wave groups and suspended sediment concentration remain vague. Likely candidate processes include an accumulation of turbulence near the sea bed during wave groups or, alternatively, the fluidization of the porous granular bed during wave groups. Under the first hypothetical process, an increase in turbulence could result in the enhanced transport of sediment away from the sea bed, and therefore increase the near bottom concentration. In the second scenario, fluidization of the sea bed during groups would reduce the stress necessary to entrain more sediment from the bed. Of course these two processes are not mutually exclusive. (EDC)

Descriptors :   *SEDIMENT TRANSPORT, *SUSPENDED SEDIMENTS, ACCUMULATION, ACOUSTIC MEASUREMENT, CANADA, CONCENTRATION(COMPOSITION), CORRELATION, ENTRAINMENT, FIELD TESTS, FLORIDA, INSHORE AREAS, OCEAN BOTTOM, OCEAN CURRENTS, POROSITY, PROFILES, RESOLUTION, RESPONSE, SAND, SCENARIOS, SEDIMENTS, SPATIAL DISTRIBUTION, SUMMER, SURF, TURBULENCE, VELOCITY, VERTICAL ORIENTATION, SEA WATER, OCEAN WAVES.

Subject Categories : Physical and Dynamic Oceanography

Distribution Statement : APPROVED FOR PUBLIC RELEASE