NUMERIC AL SIMULATION OF OREGON I.ILET : ONTROL STRUCTURES' 

 EFFECT S ON STORM ,\ND TIDE ELEVATIO NS IN PAMLICO SOUND 



PART I: INTRODUCTION 



Backg round and Objectives 



1. North Carolina's Atlantic coa.st has two largo lagoons, Pamlico 

 Sound ai.a Albemarle Sound, separated from ti:e ocean by a strand of barrier 

 islands known as the Outer Banks (Figure 1). The Outer Banks ftretch approxi- 

 mately 19C'-'« miles between Virginia Beach, Virginia; Cape Hatteras, and 

 Mcrehaad City, North Carolina. Orily three openings in the barrier islands 

 provide navigational access between Pamlico Sound and the Atlantic: Hatteras, 

 Ocracoke, and Oregon Inlet. Oregon Inlet, the northernmost of the three 

 openings, provides the fishermen and boaters of Roanoke Island and Albemarle 

 Sound the only practical means of reaching the ocean. Since the creation of 

 the present-day Oregon Inl(;t by a hurricane in 18A6, navigation there has 

 remained hazardous due to channel movements and shoals. Location of the 

 channel also has moved steadily south du^ to sediment transport by alongshore 

 currents in the past 100 years. 



2. In 1970, Congress authorized the Manteo (Shallowbag) Bay project 

 which included the stabilization of Oregon Inlet with a dual jetty system. 

 Since the addition of jetties will change the hydrodynamics of the inlet, 

 proposed structures need to be evaluated for their impact on normal tidal 

 conditions and storm surges. 



3. This study evaluates several proposed jetty configurations for 

 Oregon Inlet vJith numerical hydrodynamic models of the entire lagoon system 

 and the area around the inlet. The models are calibrated by computing tides 

 and adjusting model parameters until the computations match observed tides. 

 The calibrations are verified by storm surge simulations of two historical 

 storms (Hurricane Donna in 1960 and the March 1962 northeaster) that affected 

 the inlet. These calculations are shown to agree with marigrams recorded dur- 

 ing the storms at several tide stations on the Atlantic coast and in the bays. 



* A table of factors for converting U. S. customary units of measurement to 

 metric (SI) units is presented on page 3. 



