lower plots show actual calculated quantities and the upper plots show the 
difference in quantities. Since the bathymetry in the study area is irregular 
and the shoreline jagged, wave height and direction vary appreciably along- 
shore. However, trends are seen to be similar for the lower plots on each 
figure and, importantly, the difference in calculated quantities is random, 
that is, no systematic change in wave properties resulted from the updated 
bathymetry. Therefore, it was concluded that use of the wave time series and 
refraction results for the original bathymetry is justified. The updated 
bathymetry was employed in the later stages of the project for calculating 
refraction over beach fill borrow sites. 
Refraction Over Beach Fill Borrow Sites 
64. For an open-ocean coast, breaking wave height and direction are 
considered to be the primary factors controlling longshore sediment transport 
and subsequent beach change. The pattern of breaking waves is determined by 
the properties of the incident waves in deep water (wave height, direction, 
and period) and the bathymetry over which the waves propagate and transform. 
Alteration of the nearshore bathymetry due to removal of sediment at an off- 
shore beach fill borrow site may alter the breaking wave characteristics. The 
sediment transport rate along the beach could, in principle, be modified to 
such a degree that the naturally occurring evolution of the beach plan shape 
would be changed by an amount sufficient to have engineering significance. 
65. Two open-ocean sites are under active consideration as borrow 
sources for the project beachfill. The locations and configurations of the 
potential borrow sites are indicated on Figures 12 and 13. Herein, the borrow 
area off Sea Bright and Sandy Hook is called the northern site, and the area 
off Belmar is called the southern site. A description of the two sites and 
the available deposits is given in Appendix E. The bathymetry in the vicinity 
of the southern site is highly irregular (Figure 13), whereas regular bottom 
contours could be drawn for the northern site (Figure 12). 
66. The sites lie relatively close to shore and in water depths rang- 
ing from approximately 25 ft (8 m) to 60 ft (18 m) MLW. An 8-sec linear wave 
at these depths has a length of approximately 213 ft (65 m) and 282 ft (86 m), 
respectively, and the corresponding depth to wavelength ratios are 0.12 and 
0.21. These values are much less than 0.5, the ratio at which waves are 
39 
