51. At a later stage in this study, the grid was extended on the south 
to permit simulations of refraction over potential beachfill borrow sites 
located off the township of Belmar. The 106 by 39 grid cell extension began 
at Lake Como and ended at Manasquan Inlet. This extension made possible the 
incorporation of three profile lines from the 1985 survey not located on the 
main (original) grid. Revision of the original grid to incorporate the 1985 
profile survey information is described below. 
52. The grid was overlaid on National Oceanic and Atmospheric Adminis- 
tration (NOAA) nautical chart No. 12324 (Edition 22, dated January 1984) to 
assign an average depth to each cell, interpolating as necessary. The depths 
at the centers of grid cells were transferred to a computer file for use as 
model input. A 3-dimensional plot was made of the bathymetry to provide a 
visual check (Figure 10). 
53. Wave height, direction, and period as determined from the Phase III 
WIS hindeast provided the required offshore boundary values for RCPWAVE. The 
default lateral boundary condition is a "no-flow" condition equivalent to 
specifying a plane beach at the sides. RCPWAVE was modified to save values of 
a transformation coefficient related to wave height (described further below) 
and wave direction at fixed points alongshore at a nominal 3-m depth for input 
to the local wave refraction and breaking simulation routine employed by the 
shoreline change model. 
Model runs 
54. Test runs were made to verify proper operation of the model. 
During the testing phase, it was noted that on some runs, waves propagating 
northward, approximately parallel to shore (out of the south, Table 2), caused 
model instability. Examination of this condition indicated these waves would 
refract offshore at certain locations, a possibility not accommodated by 
RCPWAVE and of no physical significance. In order to represent waves from the 
south without concern for rare exceptions producing model instability, input 
Phase III waves out of the south were reassigned to the southeast sector. 
55. Production refraction model runs were made in an innovative way to 
eliminate the expense of making a computer run for each offshore wave condi- 
tion in the WIS 3-year time series. Direct use of the time series of wave 
height, direction, and period at 6-hr intervals would require 8,760 runs (sea 
and swell). The cost to make this enormous number of runs and to store the 
results would be prohibitive. The procedure would also be misleading since 
33 
