Publication Date:
2021-06-30
Description:
The focus of this study was the flow patterns of a flood tide near an inlet. The objectiveswere to examine flood flow patterns with particular reference to non-uniform or selectivewithdrawal as influenced by bottom topography and longshore currents, and to test theapplicability of conceptually simple analytic solutions to realistic sandy inlet bottom topographies,which often include an ebb shoal. Specifically, the applicability of three analytic solutions, twoof which include offshore selective withdrawal, to modeling of tidal water withdrawal duringflood tide under variable bottom topography and varying ratios of longshore current to inletvelocity, was examined. The three analytic solutions, including those for a horizontal (flat)bottom, a linearly sloping bottom and a logarithmically sloping bottom, together with a uniformlongshore current, were derived using potential flow theory. These solutions exhibit uniformlydistributed flows, selective offshore withdrawal, or an exaggerated offshore withdrawal,respectively, depending on the bottom slope. In order to investigate the flow patterns that exist during flood flow at a real inlet, experiments were conducted in a fixed bed hydrodynamic modelof Jupiter Inlet, Florida. Measurements were made to determine streamlines and velocities. Afield study at the prototype also tracked drogue patterns to determine streamlines and velocities.The physical model tests compared well with the field data. Comparison of thelaboratory and field data was then made to the analytic solutions to determine whether thetopography at Jupiter Inlet, which includes a well-developed ebb shoal, simulates a flat, meanlinearly or logarithmically sloping bottom. By comparing velocities at six selected points, asignificant relationship between the physical model and field data to the flat bottom analyticsolution was evident. The physical model tests and field data suggested that the flood tidal prismwas drawn from the region predominantly shoreward of the ebb shoal, thus implying a nearshoreselective withdrawal. Because the flood tidal prism was drawn from the nearshore, the flowpatterns at Jupiter Inlet did not resemble the analytic solutions of a linearly or logarithmicallysloping bottom, even though over a relatively long distance offshore, the bottom topography doesslope offshore at this inlet. In general, different inlet topographies would lend themselves todifferent analytic solutions, two examples being 1) the linearly sloping bottom of Koombana BayInlet, Australia, which shows an offshore selective withdrawal and 2) the basin-like nearfieldtopography of Jupiter Inlet which shows a more uniform nearshore withdrawal. The implicationsof this study are relevant to inlet management issues such as the mining of an ebb shoal for useas a source of beach sediment and changes in larval transport patterns due to jetty modifications. (Document has 97 pages.)
Description:
Thesis, M.S., Engineering
Keywords:
Oceanography
;
Engineering
;
Tidal inlets
;
Jupiter Island
;
Florida
Repository Name:
AquaDocs
Type:
monograph
Format:
application/pdf
Format:
application/pdf
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