PART IV: SUMMARY AND CONCLUSIONS 



121. A system of numerical models was developed to simulate coastal and 

 inlet processes near Oregon Inlet, North Carolina. The system included models 

 for wave propagation, wave-induced currents and setup, sediment transport 

 within and beyond the surf zone, and profile response (onshore-offshore trans- 

 port). Results from a separate study on numerical simulation of tides and 

 storm surge for Oregon Inlet were utilized in the present investigation. 



122. The emphasis in development of the models was on computational 

 efficiency and the ability to handle complex bathymetries and large numerical 

 grids encountered in practical engineering problems. 



123. The models of the system were tested individually and validated 

 against available analytical solutions as well as laboratory and field data. 

 All of these tests and comparisons were successful. 



124. The computational costs for the models of the system were relatively 

 modest so that long-term simulations could be performed economically with the 

 system. 



125. As a test for an extreme event, the Ash Wednesday storm of March 

 1962 was simulated with the profile response model. The calculated erosion 

 amounts of the shore-normal profiles for Bodie Island and Pea Island (on 

 either side of Ore"gon Inlet) were compared with measured values. There was 

 good agreement, especially considering the uncertainty of the measurements. 



126. As an alternative to the stabilization of the Oregon Inlet entrance 

 channel by construction of two jetties, a nonstructural solution proposed by 

 DOI was evaluated using the profile response model. The DOI solution involved 

 disposing the dredged material from the inlet channel in the nearshore region 

 with the idea that the material would be dispersed shoreward by wave action at 

 a rate sufficient to prevent dredging-induced beach erosion. On the basis of 

 a feasibility study conducted by SAW, two disposal schemes involving placement 

 of dredged material in depths of 11 and 17 ft were simulated using wave condi- 

 tions for a typical year. Various scenarios were considered, and simulations 

 were performed for 1- and 5-year durations. The results of these tests indi- 

 cated that on the average only 25 percent of the material disposed in the 

 nearshore migrated toward the shore in a year. This was not sufficient to 

 prevent dredging-induced beach erosion. An independent analysis of the 



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