HR: 09:30h
AN: OS51A-07    [PDF]
TI: Measurements of Sediment Transport in the Western Adriatic Sea
AU: * Sherwood, C R
EM: csherwood@usgs.gov
AF: U. S. Geological Survey, 384 Woods Hole Road, Woods Hole, MA 02543-1598 United States
AU: Hill, P S
EM: paul.hill@dal.ca
AF: Dalhousie University, Department of Oceanograpy 1355 Oxford Street, Halifax, NS B3H 4J1 Canada
AB: Instrumented bottom tripods were deployed at two depths (10 and 20 m) off the mouth of the Chienti River in the western Adriatic Sea from November 2002 to May 2003 as part of the EuroSTRATAFORM Po and Apennine Sediment Transport and Accumulation (PASTA) Experiment. Waves, currents, and proxies for suspended-sediment concentrations were measured with upward-looking acoustic Doppler current meters, downward looking pulse-coherent acoustic Doppler profilers, single-point acoustic Doppler velocimeters, and acoustic and optical backscatter sensors. Flow was dominated by the western Adriatic coastal current (WACC) during the experiment. Mean southward alongshore velocity 2 m below the surface was 0.10 m/s at the 10-m site and 0.23 m/s at the 20-m site, and flow was modulated by tides, winds, and fluctuating riverflow. The largest waves (3 m significant height) were generated by winds from the southeast during a Sirocco event in late November that generated one of the few episodes of sustained northward flow and sediment transport. Most of the time, however, sediment resuspension and transport was dominated by Bora events, when downwelling-favorable winds from the northeast generated waves that resuspended sediment and simultaneously enhanced southward flow in the WACC. Mean flow near the bottom was slightly offshore at the 20-m site (0.01 m/s at 3 m above the bottom), but there was no significant correlation between downwelling and wave-induced resuspension, and cross-shelf sediment fluxes were small. The combination of persistent southward flow with low rates of cross-shelf leakage makes the WACC an efficient conduit for sediment past the Chienti region. If these observations are representative of typical winter conditions along the entire western Adriatic, they may help explain the enigmatic development of Holocene shelf-edge clinoforms that have formed hundreds of kilometers south of the Po River, which provides most of the sediment to the Adriatic Sea. Future data analysis and modeling is planned to investigate the mechanism(s) that apparently limit(s) sediment leakage from the WACC.
DE: 3022 Marine sediments--processes and transport
DE: 4211 Benthic boundary layers
DE: 4219 Continental shelf processes
DE: 4243 Marginal and semienclosed seas
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting