Degree

Doctor of Philosophy (PhD)

Department

The Department of Oceanography and Coastal Sciences

Document Type

Dissertation

Abstract

A three-dimensional, high-resolution, Finite-Volume Coastal Ocean Model (FVCOM) was used to study the dynamics of Barataria Estuary located in the Southeastern Louisiana. Three numerical experiments with different discharge scenarios, including the actual discharge (average ~ 160 m3 s-1) from the Davis Pond Diversion (DPD) over three months from April to June 2010, no discharge (NO), and the proposed Mid-Barataria Diversion (MBD) with a constant discharge of 850 m3 s-1, were conducted to investigate the impacts of river diversions on salinity gradients and residence times in the estuary. The three-month average salinity indicated that surface salinity had less variation in the DPD scenario compared with that in the NO scenario, while bottom salinity differences between the DPD and the NO scenarios were as high as ~ 4. On the other hand, the maximum average salinity for both surface and bottom in the MBD scenario exhibited a reduction of ~ 12 compared with that in the NO scenario, with a larger area at the bottom than at the surface. Both the DPD and the MBD had a great impact on the residence time of Barataria Bay, where the average residence time was reduced from 15 days in the NO scenario, to 6 (4) days in the DPD (MBD) scenario, when passive particles were released at flood slack.

Barataria Pass is one of the four tidal inlets connecting the Barataria Bay with the coastal ocean and has the greatest estuarine-shelf exchange. The lateral circulation in the inlet showed a pair of counter-rotating circulation developing during flood tide, while unidirectional flow occurred during ebb tide. Analysis of 3-D momentum equations revealed that nonlinear advection is the dominant force generating lateral circulation in this narrow inlet. Model results showed that ebb tides transported freshwater seaward through this inlet to form radially spreading estuarine plumes over the adjacent continental shelf. Wind-driven coastal circulation determined the subtidal variations of the plume when the upstream freshwater discharge rate was almost constant. Particles released near the seaward side of the inlet at ebb slack could be transported into the bay, however, most of them were expelled out during the next ebb tides and floated over the convergence zone of the plume front.

Date

10-23-2018

Committee Chair

Huang, Haosheng

DOI

10.31390/gradschool_dissertations.4742

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Oceanography Commons

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