between 1940 and 1956 (Taney, 1961a; Beach Erosion Board, 1960). Taney 

 has also shown that Westhampton Beach retreated at an average rate of 

 0.6 meter per year for the interval between 1938 and 1956. This sug- 

 gests that the accretionary period documented during this study is not 

 typical of the long-term trend. Although much of the overall gain can 

 be attributed to the trapping of littoral drift within the groin field 

 and the placement of fill within the four westernmost groin compartments, 

 significant accretion also occurred on five profile lines that are pre- 

 sumed to be less influenced by the groin field (profile lines 1 to 4, 

 and 11) . The profile lines within the easternmost groin compartments 

 and immediately to the east of the groin field generally showed the 

 highest rate of nonfill related accretion. It is not known how much of 

 this accretion might be due to a general recovery from the storm of 

 March 1962. 



A natural accretionary trend, coincident with the construction of 

 the Westhampton Beach groin field, is suggested by changes measured on 

 profiles located 2 to 5 kilometers updrift and 3 kilometers downdrift of 

 the groin field. Erosional trends measured on profile lines 2, 3, 4, and 

 11 from 1962 to 1968 were reversed in 1969. The rapid shoreline advance 

 observed on profile line 11 during 1972 may be a result of fill material 

 migrating westward from the groin field. This material was apparently 

 transported seaward of the shoreline at profile line 10 since there is no 

 indication of it from the beach surveys on that line. Everts, DeWall, and 

 Czerniak (1974) documented an alongshore migration of fill material 

 placed on the beach at Atlantic City, New Jersey. Migration rates of 

 the subaerial "hump" or volume maximum resulting from two separate fill 

 projects were 2 and 3 meters per day. If the 1972 accretion observed at 

 profile line 11 on Westhampton Beach resulted from the 1970 fill, the 

 rate of alongshore movement of the volume maximum from profile lines 9, 

 10, and 11 would have been 4 meters per day. It is also possible that 

 the general accretionary trend is due to artificial nourishment associ- 

 ated with both the groin construction and with placement of material 

 dredged from the Intra-coastal Waterway. 



2. Seasonal Changes and Wave Climate . 



Monthly mean wave height and period observations (from three sources) 

 are summarized in Figure 16. The gage data are from a spectral analysis 

 of 1,024-second digital records collected by CERC four times per day, 

 using a pressure sensor located on the sea bottom, offshore of Southampton 

 (Fig. 1). Visual observations of breaking waves on a near-daily basis by 

 volunteer observers at Southampton and Westhampton indicate that the break- 

 ing waves arrive more frequently from the southeast (from the left of 

 shore-normal, to an observer on the beach) on a yearly basis. During the 

 summer months the lower waves tend to arrive from the south-southwest, or 

 slightly from the right of shore-normal. A comparison of these data with 

 the average nonfill profile changes summarized in Figure 17 shows that, 

 as expected, the higher steeper waves during the fall and winter months 

 tend to remove sand from the beaches, while the lower less steep summer 

 waves tend to rebuild the beaches. A partial beach recovery in December 



29 



