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RECURRENCE INTERVAL (YEARS) 
CASE A: PROFILE NO. 160 HURRICANES AND NORTHEASTERS 
Figure 33. Maximum recession-recurrence design curve for combined 
hurricanes and northeasters for Profile 160 
capability of this or any known model, no further analysis of Profile 82 was 
made. 
168. Case C-Profile 140. Calculations for Profile 140 illustrate the 
protection afforded by a relatively high dune. This example profile has a 
berm crest elevation of approximately 20 ft. Recession-recurrence curves for 
hurricanes (Figure 34) and northeasters (Figure 35) indicate maximum reces- 
sions of less than 30 ft for a 500-year storm. The model indicates that re- 
cession rarely exceeds 30 ft regardless of the intensity of the storm event. 
These results are consistent with the observed tendency for a dune to afford 
protection to the beach by eroding and thereby making material available for 
transport offshore. This results in a decrease in surf zone depth which 
forces incident waves to break further offshore, dissipating their energy over 
a wider beach and causing less erosion of the dune. The combined hurricane- 
northeaster curve for Profile 140 is shown in Figure 36. 
169. Case D-Profile 186. Profile 186 was selected as an example of an 
unprotected beach with a low dune, in contrast to the Profile 140 high-dune 
case. Maximum recession curves for hurricanes and northeasters are shown in 
88 
