PART III: WAVE REFRACTION ANALYSIS 
34. This chapter describes procedures and results of the wave refrac- 
tion task of the study. The wave refraction task consisted of three steps. 
As a first step, the Wave Information Study (WIS) technique (Jensen 1983) was 
used to generate a 20-year hindcast time series of wave height, direction, and 
period. In the second step, a numerical model of wave refraction was applied 
to obtain a time series of representative wave conditions at fixed points 
alongshore. The resultant wave heights and directions provided the principal 
input to drive the shoreline change model, described in Part IV. The third 
step was an evaluation of refraction over two potential open-ocean beach fill 
borrow sites. 
Wave Hindcast 
35. As discussed in Part II, there are no long-term wave measurements 
available for the vicinity of the project. Therefore, the required wave 
information was generated by means of the WIS hindcast technique. WIS pro- 
vides a 20-year hindeast for the US Atlantic Ocean coast for the years 1956- 
1975. Phase II of this hindecast includes a 20-year time series of wave 
height, wave direction, and wave period at 3-hr intervals for both sea and 
swell components at a point off the north New Jersey coast. This Phase II 
point (Station 23) is located about 30 km offshore and is shown on Figure 7. 
For the purpose of the present study, the time series of wave characteristics 
at this point was used as wave input to the Phase III transformation tech- 
nique. This technique involves transformation of the deepwater wave condi- 
tions to a specified water depth, taking into account the effects of wind-wave 
interaction, refraction and shoaling over straight and parallel bottom con- 
tours, and the sheltering of wave energy by Long Island. Bottom features on a 
horizontal scale less than 18.5 km are not incorporated in the Phase III 
transformation, i.e., grid cell dimensions in the WIS technique are on the 
order of 18.5 km. 
36. Although WIS Phase III information for the area of the project site 
is available at Station 54, which lies off the project area at a depth of 
10 m, a special Phase III run was made to compute the hindcast wave time 
series at the depth of the seaward boundary of the nearshore refraction grid. 
24 
