“Dispersal of Fluvial Sediment in the Adriatic Sea”
Dr. Courtney K. Harris
Virginia Institute of Marine Science
Monday, March 14, 2005
3:30 PM
Room 109, Crittenton Hall
Abstract
A three-dimensional numerical sediment transport model is used to evaluate dispersal
paths of fine-grained fluvial sediment delivered to the Adriatic Sea, Italy. Two types
of fluvial input are considered, each representing a different source. The largest
source of sediment, the Po River, drains 75,000 km2 and delivers an estimated 11.5 MT
yr-1 of sediment annually (Kettner and Syvitski 2005). The second source is several
smaller rivers that drain catchments in the Apennine Mountains that collectively deliver
a large sediment load to the Adriatic. Our calculations of sediment dispersal include on
sediment resuspension by energetic waves and currents, transport with the currents, and
delivery from fluvial sources. Currents are driven by buoyancy forcing and winds. Wave
bottom orbital velocities are calculated from waves predicted using the SWAN wave model,
driven by the same wind fields. Spatial structure in both waves and currents therefore is
influenced by the spatial variability present in wind fields over the Adriatic.
Observations have shown that fine-grained sediment delivered by the Po River is predominantly
packaged as fast-settling flocculates, whereas the Apennine rivers deliver slowly-settling
unflocculated material (see Fox, et al. 2004a; 2004b). This implies that sediment from the
Po River is deposited near the river mouth during floods, whereas material from the Apennine
rivers can traverse long distances. Po River sediment can be remobilized by energetic waves
soon after delivery, though, within a winter season, most Po sediment is predicted to remain
in the northern Adriatic. Apennine sediment undergoes a net cross-shore transport during a
winter season. On a regional scale, sediment flux occurs preferentially during Bora wind
events because these both set up energetic waves and intensify the western Adriatic coastal
current. Predicted depositional patterns show similarities to those observed in Holocene
accumulation maps. Deposition is thickest near the Po River mouth, and the Po sediment bed
extends south towards the Apennine shelf. Sediment is preferentially deposited on the
northern side of the Gargano Peninsula. These spatial patterns may be equally dependent
on the spatial structure of the wave field compared to convergences in the currents.
Biography
Dr. Harris received her M.S. and Ph.D. degrees in Environmental Science from the
University of Virginia. Her research is focused on using a variety of coastal
ocean models (e.g. ROMS, ECOM-SED, NCOM) to quantify sediment transport in diverse
environments, including the Adriatic Sea, the California continental shelf, the New
York Bight, Chesapeake Bay, and offshore of the Waiapu river, NZ. Dr. Harris is
currently an Assistant Professor in the School of Marine Science at VIMS.
Reception before seminar at 3:00 PM
Crittenton Hall
Old Dominion University
Norfolk, VA 23529
757-683-5548
Last updated 2/04/2005.
This page is maintained by
Gabriel Franke
Copyright Info: Old Dominion University 2005
