may be explained by the different methods of analysis and somewhat different 
time periods. In response to the threat of breaching caused by severe erosion 
along this stretch of shoreline, 1,824,000 cu m of fill were emplaced on the 
critical zone between November 1982 and August 1983. A monitoring study of 
the fill was made by Phillips, Psuty, and McCluskey (1984) (see also Slezak 
et al. 1984). 
21. Process characteristics. Data on visually measured breaking wave 
characteristics (wave height, direction, and period), longshore currents, 
sediment grain size, and shoreline and beach profile change at various loca- 
tions along Sandy Hook have been published in a number of reports and articles 
(e.g., Nordstrom 1975, Nordstrom et al. 1982, Allen 1985). Of particular 
relevance to the wave refraction task (Part III) are the breaking wave condi- 
tions, for which the aforementioned reports contain data spanning several 
hundred measurement days. Typical values of breaking wave height are in the 
range 0.1-0.8 m; wave period in the range 3-9 sec; and breaking wave angle 
5-15 deg, where a positive angle corresponds to waves out of the south. 
Measured waves were generally out of the south with relatively large breaking 
angles. Longshore sand transport rates in the aforementioned reports were 
estimated through either changes in shoreline position or from predictive for- 
mulas based on breaking wave data. The erosion rate obtained for the critical 
zone for recent times (1971-1978) is given as 270,000 cu m/year (Allen 1981a) 
or about 70 percent of the transport rate determined by Caldwell (1966), dis- 
cussed below. 
22. Allen and Nordstrom (1977b) report preliminary results of a numer- 
ical modeling study that involved wave refraction and shoreline modeling of 
the critical zone of Sandy Hook. A wave ray refraction model was coupled to 
a shoreline change model. Final results do not appear to have been published. 
In their preliminary work, it can be inferred that some interpretation prob- 
lems arose in the refraction modeling due to caustics and the irregular spac- 
ing of wave rays alongshore. No shoreline change model results are given, but 
the large alongshore grid spacing (100-1000 m) and long time step (1 year) 
would produce results of questionable accuracy and validity in the statistical 
sense. In the present study, an advanced refraction model allowed calculation 
of wave refraction at a fixed interval alongshore (150 m), and the shoreline 
model incorporated a finer alongshore grid spacing of 50 m and a time step of 
6 hr. These specifications are appropriate to the length and time scale of 
Vi 
