Date Awarded

2000

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Virginia Institute of Marine Science

Advisor

Carl T. Friedrichs

Committee Member

L. Donelson Wright

Abstract

To understand the morphodynamics of the inner shelf, a benthic boundary layer tripod supporting 6 point-measuring current meters, an acoustic Doppler current profiler, and three near-bed profiling acoustic backscatter sensors documented storm and swell conditions during October, 1996, at a depth 13 in on the inner shelf off Duck, North Carolina. The relationship between eddy viscosity and eddy diffusivity during storm and swell conditions was examined using data collected in October 1996 on the inner shelf off Duck, NC. Sediment suspension models, including Rouse-type diffusion models, combined advection and diffusion models, and a Rouse model with a thickened wave boundary layer, were compared to determine which model best reproduces observed sediment concentration profiles. A physics-based morphodynamics model was then developed to determine which components of hydrodynamic forcing and resulting sediment transport are predicted to be most significant to morphological change outside the surf zone on the inner shelf of the Middle Atlantic Bight. The simplest possible analytical solutions were sought for depth-dependent currents driven by the along- and across-shelf components of the wind and by waves via Stokes return flow and boundary layer streaming. Predicted currents and sediment concentrations were compared with observations collected at 13 m depth off Duck, NC, during October, 1996. Sediment transport and morphologic change were modeled and the morphologic change model was applied to 24 significant storms, which were documented by before-and-after shoreface profiles collected by the Field Research Facility of the US Army Corps of Engineers at Duck, NC, between 1987 and 1993. Significant correlations were found between observed shoreface volume change between 600--800 in offshore and predicted depth change on the inner shelf due to across-shelf sediment flux. Overall, correlations between observed and predicted change were higher for wave-driven components of sediment flux than for wind-driven components.

DOI

https://dx.doi.org/doi:10.25773/v5-f908-bv18

Rights

© The Author

Download

Share Feedback

Included in

Oceanography Commons

Share

COinS