Changes in the MSL shoreline position and unit volume for profile 

 lines 1 to 11 during the study period are summarized in Figure 10. The 

 same changes also appear in Appendixes C and D, with distances and vol- 

 umes referenced to the MSL position and beach volume in October 1962. 

 These data show alternating intervals of accretion and erosion through- 

 out the study, with only small net changes on the profile lines away 

 from the influence of the groin field. The changes on profile lines 5 

 to 9 are a result of the groin field and artificial fill. Profile lines 

 1 to 4 are presumably undergoing more "natural" changes, although these 

 changes may also be caused by the groin field. The U.S. Army Engineer 

 District, New York (1976) has suggested that the changes measured on the 

 easterly profiles are influenced by the placement of dredged material 

 from the Intracoastal Waterway, which runs along the north side of the 

 barrier island. However, the quantities and extent of dredged-material 

 placement are not well documented. 



I. Short-Term Changes . 



Twenty-eight pairs of profile surveys were made shortly before and 

 after significant coastal storms (Table 2). Typically, these storms are 

 winter northeasters— extratropical low-pressure systems which develop in- 

 land, strengthen as they reach the coast, and then move fairly rapidly 

 toward the north-northeast. The storms listed in Table 2 are not the 

 only storms which occurred during the study, and may not even include 

 the most damaging storms. For example, the majority of the listed storm 

 changes occurred during the three scheduled 10 weekly surveys (17 of 28 

 storms) . The table also shows that very few surveys were made immediately 

 after storms. Since there is often a very rapid recovery of the beach 

 immediately after storm erosion, the changes shown in Table 2 are con- 

 sidered to be conservative estimates. 



A detailed analysis of the 17 December 1970 storm (a moderate north- 

 easter) and its effect on the profile lines at Westhampton Beach is pre- 

 sented in DeWall, Pritchett, and Galvin (1977). The September 1967 storm 

 (Hurricane Doria) generated coastal waves up to 4.6 meters in height, as 

 measured by the CERC wave gage at Atlantic City, New Jersey (Fig. 1). 



The beach profile change data in Table 2 are average values of the 

 change in MSL position and unit volume above MSL for profile lines 1 to 



II. Changes by profile line for each of the storms are plotted as histo- 

 grams in Figure 11, which clearly shows that for any given storm both 

 accretion and erosion occurred at different profile lines. The figure 

 also shows that a given profile line may have undergone significant ero- 

 sion during one storm and significant accretion during another. The 

 greatest amount of erosion that was measured resulted from the storms of 

 March 1973, 18 February 1969, February 1972, and September 1967 (Hurri- 

 cane Doria) . 



Two storms during 7 to 12 November 1968 caused considerable property 

 damage near profile line 8 (Fig. 12), but are not included in Table 2 

 because the prestorm survey was in March 1968. During the interval 27 



