March to 19 November 1968 the shoreline at profile line 8 eroded 18 

 meters. It is not known what percentage of this erosion was due to the 

 November storms, since the profile was still adjusting to the groin which 

 was constructed 75 meters updrift in 1965. A total of 562,700 cubic 

 meters of sand was lost from the 1,800-meter reach west of the 11-groin 

 field due to the 12 November 1968 storm (U.S. Army Engineer District, 

 New York, 1969). Based on poststorm inspections and examination of air 

 photos, it was reported that the November 1968 storms caused the most 

 damage during this study period (G.K. Nersesian, Chief, New Jersey 

 Planning Group, U.S. Army Engineer District, New York, personal communi- 

 cation, June 1978) . 



Other than storms, the significant short-term profile changes meas- 

 ured are directly attributable to groin construction and beach-fill 

 events. Losses similar to the large losses previously noted on profile 

 line 8 also appear on profile lines 7, 8, and 9 after completion of the 

 first field of groins (Apps. C and D) . During the 2-year period after 

 groin construction, the shoreline at profile line 8 eroded at 20 meters 

 per year, and the unit volume loss was 9 cubic meters per meter per 

 year. These losses confirm that the groins were effectively trapping 

 littoral drift being transported to the west. 



The large gains in sand volume observed on profile lines 8 and 9 

 represent the two beach- fill projects in 1969 and 1970. The emergency 

 fill placed during March, April, and May 1969 is quite apparent on pro- 

 file line 8 (App. D). The time of this fill coincides with a period of 

 natural accretion observed on most of the other profiles. The second 

 and much larger fill project (2 7 October 1969 to 31 October 1970) was 

 in conjunction with the construction of groins 12 to 15 (Fig. 4 and 

 Table 1). This fill totaled 1,490,000 cubic meters of material (deter- 

 mined from surveys in the borrow area) placed over 1,800 meters of shore- 

 line. Since the borrow area was in the lagoonal sediments of Moriches 

 Bay, not all fill material was of suitable sand size. Before- and- after 

 surveys of fill on profile lines 8 and 9 indicate that at least 175 cubic 

 meters per meter of material was placed on the beach above MSL. Since 

 the surveys did not include all of the dune profile, this value is a 

 minimum. 



2. Long-Term Changes . 



In addition to the short-term changes, which are often quite large, 

 the data in Figure 10 suggest that the profiles undergo seasonal cyclic 

 changes and also a longer term net change which may or may not be cyclic. 



Figure 13 shows the monthly average MSL shoreline position and unit 

 volume for each of the profile lines. The "zero" MSL position and unit 

 volume in the figure represent the mean of the monthly averages for each 

 profile line. These data show that changes are actually seasonal with 

 the least amount of sand on the beaches from January to May and the most 

 sand on the beaches from June to December. However, relatively few sur- 

 veys were made in summer, and the data shown in the figure for July are 

 based on only three surveys over the 11 years (1963, 1964, and 1967); 

 therefore the data may be less representative of average summer conditions. 



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