Nears'nore Model 



48. Plates 17-19 illustrate the excellent agreement between compu- 

 tations for the March 1962 storm in the nearshore model and the prototype 

 data. Once again, the datum shifts listed in Table 3 are included in the 

 field records. The computations match all 11 sites qu;te closely. Davis, a 

 gage not represented in the offshore model due to cell sizes, has no datum 

 shift included in the prototype record. It can be expected that any shift 

 would be of the same order as nearby sites surh as Wrightsville Beach. The 

 computations of Stumpy Point agree with the prototype because Stumpy Point Bay 

 can be reasonably approximated by the small cells in the nearshore grid. 



49. Plate 20 shows the flow patterns through Oregon Inlet for the peak 

 of the March 1962 northeaster (hour 60, or noon GMT on 7 March) in the near- 

 shore model. Plates 21 and 22 show marigrams for eight locations (Figure 3) 

 in Oregon Inlet, while Plates 23-26 show the corresponding velocity records. 

 The velocities at the inlet tell what happened during the storm. The normal 

 ebb-flood cycle of tidal flow through the inlet was halted by the surge sea- 

 ward of the inlet on 7 March. For a 22-hr period between 8 a.m. GMT on 



7 March (hour 56 in the calculations) and 6:00 a.m. GMT on 8 March (hour 78), 

 the flow was entirely into Pamlico Sound. According to computations, the peak 

 flow velocity was about 9 fps, or about twice the normal tidal velocity. At 

 the peak of the storm about 630,000 cfs of water flowed into Pamlico Sound. 

 Figure 10 shows the computed surge contours at noon GMT on 7 March (hour 

 60) for the area of Oregon Inlet, Roanoke Island, and the nearby mainland. 

 The head difference driving the flow is about 5 to 6 ft. 



50. Comparison of the nearshore model calculations of Hurricane Donn^ 

 with the prototype data can be found in Plates 27-29. Most of the phase 

 differences found in the offshore model computations do not appear ■'.n the 

 nearshore model due to the increased resolution in this grid. As rfith the 

 offshore model, the effects of wave setup appear in the plots for Hatteras and 

 Nags Head. Considering the severity of Hurricane Donna, and the resolution of 

 the grid for the nearshore model. Plates 27-29 show that this model can 

 simulate a historical hurricane. 



51. Plate 30 illustrates the severity of the ebb flow through Oregon 

 Inlet at the peak of Hurricane Donna (10:00 a.m. GKT, 12 September, or hour 22 

 of the computations). Plates 31 and 32 show the surge histories of the 



32 



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