COASTAL PROCESSES AT OREGON INLET, NORTH CAROLINA

James T. Jarrett

Abstract


Coastal processes In the vicinity of Oregon Inlet, North Carolina were studied in connection with the design of a dual jetty system for that inlet. Oregon Inlet is the northernmost breach through the "Outer Banks" of North Carolina and is situated approximately 40 miles (64 km) north of Cape Hatteras and 90 miles (145 km) south of the ocean entrance to Chesapeake Bay, see Fig. 1. The improvements planned for this inlet are part of an overall plan of development directed at enhancing the fisheries industry of North Carolina through the provision of a modern fisheries center at the village of Wanchese, located on Roanoke Island, see Fig. 1. The general layout of the proposed jetty system is shown on Fig. 2. Certain aspects of this design will be referred to later in this paper. In addition to their structural and functional aspects, a major part of the design of the jetties concerns the structure-shore interaction and means whereby adverse shore processes will be prevented in operating the project. Obviously, the construction of jetties or any other type of littoral barrier at an inlet would disrupt the normal movement of and processes associated with longshore sediment transport. Therefore, artificial means of moving littoral materials around a stabilized inlet must be employed to assure that the adjacent beaches are maintained in at least the same state existing prior to any navigation related improvements. The need for a reliable sand bypassing method at Oregon Inlet is accentuated by the fact that the inlet is bounded on the north by the Cape Hatteras National Seashore and on the south by the Pea Island Wildlife Refuge, both of which are Federally owned beach areas managed for the purpose of preserving the natural quality of the Outer Banks environment. The design of a sand bypassing system must be based on a knowledge of the existing shore and inlet processes, particularly as they relate to the rate and directional distribution of longshore sediment transport. When the existing conditions are known, it is possible to estimate the sediment transport rates with the structures in place and, thus, predict the amount and direction in which material will have to be bypassed. This paper describes the approach taken to evaluate the existing and future longshore sediment transport in the vicinity of Oregon Inlet and briefly discusses the proposed bypassing system for the stabilized inlet.

Keywords


coastal processes; Oregon Inlet; North Carolina

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