Uiiclas^i fled . 



SECURITY CLASSIFIC* TION OF THIS PAGEfWTi^. P.r. Enl.r.tfJ 



20. AflSTTACT (Continued). 



shelf anJ was used to propa?.ate storm effects f.-om deep water to the finer 

 resolut-.on models. The nearshore model extended from Cape Henry to Cape 

 Lookout, and p'ovided finer detail aloi.g the Outer Banks, within Pamlico ?nd 

 Albema.-le Souncs, and at Oregon Inlet. This model wf s used for both tide 

 and svrge simulations and was the primary tool for establishing structural 

 efft ::s under storm conditions in the Oregon Inlet vicinity. It also was 

 used to provide boundary conditions for the most detailed model of the study 

 kncwi as the shore process model. The shore process model emoompassed less 

 thai' 85 square miles centered about Oregon Inlet and provided high resolution 

 at ':he inlet and in the surf 2 one. It provided more realistic circulation 

 patterns of the InJet, the effects of jetties on inlet flow, and hydrodynamic 

 data for concurrent numerical sediment transport studies. 



Data collected for previous physical model studies were supplemented by 

 acditioual data from :-OAA ai:d unpublished SAW letter reports for satisfactory 

 calibration and verification of the models under existing tidal conditions 

 and for two severe storms of record: the March 1962 northeaster and 

 Hjrricane Donna (1960). Two structural alternatives (involving parallel 

 jetties with 2,500- and 5,000-f t-wide spacings) were studied, and their effects 

 wijre determined to be limited to the inlet under tidal conditions and to the 

 iinnediate inlet vicinity under circumstances approximating Hurri.ane Donna. 

 Tlie maximum possible influence attributable to inlet restriction was determined 

 by simulations with complete inlet closure (this was not under consideration as 

 ai improvement plan) under hurricane Donna conditions, and no changes were 

 nDted beyond a 12-mile radiis of the inlet. Within that distance, elevation 

 increases of 2.4 ft and I.4 ft were indicatsd at the Pea Island Coast Guard 

 Station and Oregon Inlet Marina, respectively, with total inlet closure under 

 Donna-like conditions. For 2,500- and 5, OOG-f t-wide jetty alternatives, no 

 significant changes were noted during Donna simulations, the 2,500-ft case 

 producing water-elevation increases of 0.6 ft and 0.3 ft, respectively, for 

 the above stations. Tidal simulations with structural alternatives indicated 

 local variations to be limited no the inlet. 



Simulations at very fine grid resolution were made using tlie shore 

 process luodel to provide hydrodynamic data for numerical sediment transport 

 studies covering the normal range of tides with no jetties, four structural 

 alternatives with a mean tide, and the historical March 1962 northeaster 

 with no jetties. 



U nclassifie d 



SECuniTY Classification of 



