HR: 09:40h
AN: OS31A-05    [Abstracts]
TI: Process Model of Sorted Bedforms
AU: * Sherwood, C R
EM: csherwood@usgs.gov
AF: U.S. Geological Survey, 384 Woods Hole Road, Woods Hole, MA 02543-1523 United States
AU: Trembanis, A
EM: atrembanis@whoi.edu
AF: Woods Hole Oceanographic Institution, Mail Stop 11, Woods Hole, MA 02543-1050 United States
AU: Traykovski, P A
EM: ptraykovski@whoi.edu
AF: Woods Hole Oceanographic Institution, Mail Stop 11, Woods Hole, MA 02543-1050 United States
AB: Complex sorted bedforms, also known as rippled scour depressions, have been modeled previously using rules-based approaches developed from non-linear complexity theory. The models have had some success in explaining the origin and maintenance of sorted bedforms in a heuristic manner, but fall short of demonstrating a detailed understanding of the mechanics involved. Here we describe efforts to apply a deterministic model that includes detailed processes for hydrodynamics and sediment dynamics. Our objective was to determine whether a high-resolution application of a fairly standard collection of process models was sufficient to explain the formation and/or maintenance of these ubiquitous features. The three-dimensional physical oceanographic model is the hydrostatic Regional Oceanographic Modeling System (ROMS; http://marine.rutgers.edu/po/index.php?model=roms) and includes formulations for non-cohesive sediment resuspension and armoring, ripple geometry, and bottom stresses under wave and currents. A two-equation turbulence submodel was used to parameterize eddy viscosity and sediment diffusivity. Waves were modeled with the community model SWAN. We modeled a simple test case that represents the inner shelf of an enclosed basin, forced by winds and waves. Separate simulations were designed to 1) test the potential for formation of sorted bedform features from mixed sediment assemblages and 2) test the persistence of imposed features to the dispersive processes of sediment transport. We will present the results of these simulations and compare them with the heuristic model results.
DE: 3022 Marine sediments--processes and transport
DE: 3045 Seafloor morphology and bottom photography
DE: 4219 Continental shelf processes
DE: 4255 Numerical modeling
SC: Ocean Sciences [OS]
MN: 2005 Joint Assembly