localities. Most heights were recorded to the nearest foot as requested 

 in the form instructions, but where heights were recorded to fractions 

 of a foot, they are rounded off in the office to the next highest foot. 

 Among other things, the histograms indicate the following: 



(1) Typical wave heights along the northern half of the U. S. 

 Atlantic coast are low. For the seven localities averaged as a whole, 

 the mode (the most frequently observed wave height) is only 1 foot, and 

 the mean is 2.0 feet. This mean of 2 . can be compared with the mean of 

 1.7 feet during the same 3 months obtained for this same area in the 

 CERC-USCG Cooperative Surf Observation Program. 



(2) The largest mode of any histogram is 3 feet (Jones Beach), and 

 the maximum observed wave height is 7 feet (Jones Beach and Plum Island) . 



(3) Heights are generally greater on Long Island beaches than on 

 New Jersey beaches. In this region, the percentage of calm conditions 

 (0 wave height) increases progressively to the south. 



3. Effects on Sand Level Changes 



By comparing the height histograms in Figure 11 with maximum 

 erosion and accretion in Table II or on Figure 7, a positive correlation 

 is apparent between mean wave height and maximum, 1-week, sand level 



TABLE III 

 SAND LEVELS AND ENVIRONMENTAL FACTORS 



Locality 



Beach 

 Slope 



Maximum 



1-Week 



Erosion 



Modal 



Wave 



Height 



Mean 

 Wave 

 Height 



Sand 

 Size 



Mean 



Tidal 



Range 



Westhampton 

 Beach 



0.061 



2.2 



2 



2.3 



medium 

 to fine 



2.9 



Jones Beach 



0.059 



4.0 



3 



2.7 



medium 

 to fine 



3.6 



Long Beach 



0.049 



2.6 



1 



2.1 



medium 

 to fine 



4.1 



Atlantic City 



0.032 



2.5 



1 



2.2 



fine 



4.1 



Ludlam Island 



0.033 



1.0 



1 



1.7 



fine to 

 very fine 



3.8 



NOTE: Beach slope is from Figure 6 between and plus 5 feet MSL. 



Maximum 1-week erosion is from average of two profiles in Table 

 II. Modal wave height is from Figure 11. Mean wave height is 

 from Appendix F. Except for beach slope, all values are in feet, 



19 



