grid is small. The small difference means that the only slightly more sedi- 
ment leaves the grid than enters it, producing a relatively low rate of shore- 
line erosion. This result is considered to be incorrect in view of the his- 
torical trend of shoreline recession. For example, the rates obtained by 
Caldwell (see Figure 6) indicate a net transport rate out of the project area 
of approximately 174,000 cu yd/year (493,000 minus 319,000). 
124. The suspected cause of the low net transport rate is the limited 
representation of the shadowing effect of Long Island in the wave refraction 
modeling. In the refraction study described in Part III, it was assumed that 
a single WIS hindcast would be sufficient to represent the wave climate over 
the entire study reach (approximately 16 miles). However, if wave shadowing 
is proven to be a significant factor, it would be necessary to perform the WIS 
hindeast at several locations along the reach and develop a methodology to 
incorporate these individual hindcasts in the nearshore refraction calcula- 
tion. This level of effort was beyond the scope of the present study. 
125. Based on the successful calibration and verification of shoreline 
change at Sandy Hook, the wave input and shoreline model in their present 
forms are believed to have restricted applicability for evaluation of the 
relative merits of beachfill designs. A comparison of alternative designs was 
not performed in this study. 
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