Cap" would be more severe than that shown for the "Wide Berm + 1-ft Cap" at 

 the 500-year return period. It is possible that although the proposed im- 

 provements at Roughans Point would offer considerable protection against 

 lesser northeasters, the flood levels for the SPN might be higher after the 

 improvements. Without the improvements, water will begin returning to the 

 ocean over the north wall at approximately 11 ft NGVD. This outflow of water 

 considerably lessens the probability of extreme interior flood levels. With 

 the improvements, this outflow would be prevented by the increased wall 

 heights until much higher water levels. The lack of data to ascertain the 

 relative importance of outflow over the walls versus the outflow at the 

 western edge of the Roughans Point area at extreme interior flood levels makes 

 definitive conclusions difficult. 



117. For the still-water locations the numerical storm surge model 

 results showed that the Broad Sound maximum water levels produced by the 

 ensemble storms were efficiently conveyed throughout the Saugus-Pines River 

 system. Differences between outside and inside water levels were always small 

 with the inside level usually slightly higher. The time-history of the SPN 

 surge might be more peaked. This peaked profile would likely suffer more loss 

 through the inlet and channel system, but this loss would be offset by the 

 local wind setup of the shallower water of the flood plain (the cause of the 

 higher interior levels during the simulations). Therefore, the predicted 

 result of the SPN still-water level would be that the whole study area would 

 flood to the level of the SPN in Broad Sound. 



Conclusions 



118. Stage-frequency curves for 15 possible structure combinations at 

 Roughans Point and for 14 still-water level locations were presented and dis- 

 cussed. The potential error associated with each step of the procedure was 

 discussed. A more formal determination of the probable error of the selection 

 process was presented. Finally the estimated impact of the SPN was discussed 

 for both interior flooding at Roughans Point and the still-water locations. 



119. At Roughans Point, where flooding is caused by the overtopping of 

 seawalls by storm waves, physical, numerical storm surge, numerical wave, 

 flood routing, and probability models were needed. Multiple combinations of 

 possible seawall-revetment structures were modeled. Major differences among 



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