PART IV: DISCUSSION 



56. The appendixes include data for 46 unique combinations of 13 

 storms from 7 localities. Three storms are reported for Nauset Beach, four 

 each for Misquamicut and Westhampton, five for Jones Beach, and ten for 

 Atlantic City, Ludlam Beach, and Long Beach Island. Results are based on 94 

 profile lines and nearly 1,100 individual profile line surveys. This unique 

 collection of data provides an overview of the shape, magnitude, and 

 variation of storm-induced beach changes. In this part, the data set will be 

 examined and a number of relationships will be discussed. The discussion 

 will center on "median changes" defined as the median change (e.g. median 

 volxime change) of all the profiles on a particular beach for a particular 

 storm. The "median storm change" will also be discussed and is defined as 

 the median change computed from the medians of a number of storms. 



57. Table 5 summarizes the data from individual storms listed in the 

 appendixes. This table is similar to Table 4-6 in the SPM (1984) but 

 includes updated and additional data. 



Shoreline and Slope Changes 



58. One major finding of the study is the relative insensitivity of 

 both the msl shoreline position and the beach slope at msl to storm changes. 

 This was found to be generally true regardless of locality or storm. Of the 

 549 profile-survey combinations for which a msl shoreline change could be 

 computed, 81 percent eroded based on volumetric changes (regardless of 

 magnitude) while only 54 percent of the lines had erosional shorelines. 

 Although poststorm recovery (which would affect the shoreline position) is 

 certainly a factor on the 46 percent of the lines which showed shoreline 

 accretion, there is considerable evidence indicating that the shoreline 

 position acts as a pivot point. A number of examples of this can be seen in 

 the profile plots throughout the appendixes. Profile line 9 from Long Beach 

 Island during the 12 November 1968 storm (Appendix F) is a good example with 

 a volume loss of -44.5 m^/ra and a shoreline change of less than 1 m. Of 

 course, many exceptions exist and positive and negative shoreline changes up 

 to 30 m were measured. 



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