HR: 09:45h
AN: OS51A-08    [PDF]
TI: Sediment dispersal pathways on the Western Adriatic continental shelf
AU: * Fain, A M
EM: afain@ocean.washington.edu
AF: UW School of Oceanography, Box 357940, Seattle, WA 98115 United States
AU: Ogston, A
EM: ogston@ocean.washington.edu
AF: UW School of Oceanography, Box 357940, Seattle, WA 98115 United States
AU: Miserocchi, S
EM: stefano.miserocchi@bo.ismar.cnr.it
AF: Insituto di Geologia Marina, Cosiglio Nazionale delle Ricerche Via Gobetti 101, Bologna, 40129 Italy
AU: Sternberg, R
EM: rws@ocean.washington.edu
AF: UW School of Oceanography, Box 357940, Seattle, WA 98115 United States
AU: Palinkas, C
EM: palinkas@ocean.washington.edu
AF: UW School of Oceanography, Box 357940, Seattle, WA 98115 United States
AB: A 100-year flood event of the Po River during October 2000 resulted in a thick, greater than 15cm, sediment deposit on the subaqueous delta in close proximity to the main Po distributaries. The processes that contribute to and redistribute the modern deposit were investigated by deploying an instrumented benthic tripod along the 12-m isobath, from January 2001 to May 2002, which collected time-series data of nearbed sediment transport parameters. An additional series of deployments occurred from October 2002 until May 2003, 3km south of the initial Po tripod, providing a third winter of time-series data. Spatial variations in processes were evaluated by examining water-column salinity, temperature, and sediment concentrations that were collected during nine seasonal cruises between December 2000 and May 2003. The dispersal of sediment away from the Po River mouth can be largely attributed to both surface plume and bottom boundary layer (BBL) processes. In environments with larger mean waves and currents, such as on the northern California and Amazon continental shelves, the BBL sediment load is almost always larger than the surface plume load over the depositional site. A majority of the Po sediment falls out of the water column in the form of flocs inshore of the 6-m isobath, but there is still sediment carried in the surface plume offshore of the 6-m isobath. During relatively calm conditions, sediment load in the Po River surface plume over the delta has been observed to be up to 5 times larger than that in the BBL along the 10- and 15-m isobaths. During storms, which occur about 10% of the time along the western Adriatic continental shelf, the BBL sediment load can exceed the surface plume load and the along-isobath currents can be enhanced, providing an opportunity for a considerable amount of resuspended sediment to be advected in the BBL. Bora wind resuspension events increase surface plume velocities and coastal currents, as well as adding to nearbed shear stress and BBL transport. The sediment transport dynamics are reflected in the distribution of flood sediment on the Po River delta, with most of the sediment being initially deposited in relatively close proximity to the river mouth from the surface plume and a small fraction of this being subsequently resuspended in the BBL during storm events and transported southwards.
DE: 3022 Marine sediments--processes and transport
DE: 4558 Sediment transport
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting