PART III: PROFILE RESULTS 



43. The data presented in this report have been described by Birkemeier 

 (1985a). Some of the discussion from that report is repeated here as an aid 

 in interpreting the data. Profile changes at the FRF occur at time scales 

 ranging from minutes to annual cycles and longer. Time scales resolvable with 

 the data in this report vary between a few days and 1 to 2 years. Though the 

 profiles have varied in configuration from nearly unbarred to triple barred, 

 they typically exhibit a double bar with a narrow and well-defined inner bar 

 and a broad outer bar. Figure 8 illustrates five of the configurations ob- 

 served during the study. 



44. The profile envelope defined by all surveys of line 188 is shown in 

 Figure 9. The plot of maximum vertical change in the upper half of Figure 9 

 indicates most profile activity is restricted to depths less than 7 m with 

 little measurable vertical variation at deeper depths (only 15-cm maximum 

 variation at 8-m depth). It is not clear how much of this 15 cm is real. 

 Birkemeier (1985b) examined the changes within the data set caused by storms 

 and found that significant storm-induced bed-level changes (>3 cm) occurred at 

 depths less than -6.4 m relative to mean low water (-6.8 m below National 

 Geodetic Vertical Datum, NGVD) . 



45. One of the best indicators of profile configuration and activity is 

 the location of the bar crest. Large changes to the profile in terms of 

 volume changes always result in movement of the bar system. Minor storms 

 typically force only the inner bar offshore, while larger storms may move both 

 bars offshore, depositing sand in deeper water. Storm changes were rapid, 

 occurring over periods of 1 to 5 days. The rapidity of these changes is 

 discussed further in Sallenger, Holman, and Birkemeier (1985). 



46. Onshore bar movement usually corresponded to periods of low waves 

 between storms. The speed and the amount of recovery were affected by the 

 wave conditions and by the poststorm configuration of the profiles. All the 

 bar features tended to disappear during extended periods of low wave condi- 

 tions . 



47. An example of the modifications caused by storms is shown in Figure 

 10. The surveys bracket a series of three storms with the most severe 

 occurring 13-15 November 1981. In contrast, the slow recovery from the 

 changes caused by the fall 1981 storms occurred during 6 months of relatively 



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