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Title: Functional design of control structures for Oregon Inlet, North Carolina : hydraulic model investigation
Authors: United States. Army. Corps of Engineers. Wilmington District.
Hollyfield, Noel W.
McCoy, James W. (James Wesley), 1946-
Seabergh, William C.
Keywords: Control structures
Hydraulic structures
North Carolina
Outer Banks
Oregon Inlet
Hydraulic models
Coastal structures
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; HL-83-10.
Description: Technical Report
Abstract: Oregon Inlet, the northernmost inlet through North Carolina's barrier islands known as the "Outer Banks," is a natural channel conducting flow between the Atlantic Ocean and extensive open bay sounds. As is typical of many natural inlets, navigation through the inlet can be dangerous due to shallow shifting sand shoals. The necessity of continued maintenance dredging and the exposure of commercial and private craft to shoaling and breaking waves indicate that inlet stabilization by jetties is desirable and should be investigated. The design study for the Manteo (Shallowbag) Bay Project included construction and testing of a physical model of Oregon Inlet. Model scales were 1:300 horizontally and 1:60 vertically. The model reproduced 12 square miles of ocean area to the 60-ft-depth contour and 17 square miles of Pamlico Sound. Initially, the model was molded of concrete; however, during the latter phase of the study, the entrance channel and vicinity were removed and molded with crushed coal for a movable-bed study. An extensive set of field data was collected and analyzed for use in model verification. The verification process indicated that tidal velocities and elevations were in satisfactory agreement with the prototype and the model could be reliably used as a predictive tool to investigate the effect of various jetty lengths, alignments, and spacings on flow conditions through the inlet and on tidal variations within Pamlico Sound. Model testing included the study of jetty alignment, length, and spacing and the effects of the jetty structures on tidal exchange and on the flow through Bonner Bridge. Also, steady-state ebb and flood storm surges were reproduced and the effects of the jetties on these flows examined. Staged jetty construction tests aided in determining the best construction sequence to limit excessive scour velocities. Sediment tracer tests indicated the shape and size of fillet development adjacent to the jetties. The movable-bed tests provided information on the effects of jetties on channel alignment for both normal tides and during storm surge conditions. The effects of bottom protection at the Bonner Bridge and the placement of sills in Davis and Middle Sloughs also were evaluated. It was concluded that the plan 2 jetty alignment with 2,500-, 3,500-, or 5,000-ft spacing would not negatively impact the tidal exchange, storm surge flows, or flow through Bonner Bridge. However, the larger spacings may permit bifurcation of the entrance channel or a more curvilinear channel. NOTE: This file is large. Allow your browser several minutes to download the file.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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