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RETURN PERIOD, YRS 

 LEGEND 

 rau STAGE FREQUENCY 

 RECRESSED ROUGHANS POINT INTERIOR 



REGRESSION CHECK 

 UIDE BERN + 1FT CAP 



Figure 56. Raw and regressed stage-frequency curves, "Wide Berm + 1-ft Cap" 



process, the 150 events were divided into three sets of 50 events each. Each 

 of these sets was processed separately producing three stage-frequency curves. 

 These three curves were generated for each numerical gage for the still-water 

 level locations as well as for each of the six structure combinations at 

 Roughans Point. As was mentioned in Part II, 150 events were more than 

 necessary to produce consistent results for the still-water locations. This 

 assertion was confirmed when stage-frequency curves derived separately from 

 the three sets of 50 events were plotted for each still-water location. For 

 most of the locations there was not a discernible difference between curves 

 from the three sets. Figure 57 contains the three stage-frequency curves for 

 Oak Island which had the greatest variation of all the still-water locations. 

 As can be seen from this figure the variation resulting from selecting a 

 limited number of events to represent all possible events is negligible for 

 the still-water locations. 



111. The potential error caused by the selection process is much greater 

 for stage-frequency curves for the interior of Roughans Point than for the 

 stage-frequency curves for the still-water level portion of this project. The 

 flooding levels in the interior of Roughans Point are dependent not only upon 



86 



