5 Harbor Response to Wind 

 Waves and Swell 



Numerical model studies of the harbor response to wind waves and swell were 

 directed primarily toward assessing the operational performance of alternative 

 harbor modifications. Results, especially at existing and proposed new pier 

 areas, are summarized in this chapter. Amplification factors are presented in the 

 following section. The final section gives H s values exceeded 10 percent and 

 1 percent of the time, a result more directly applicable to operational perfor- 

 mance. The H , values are derived from a combination of amplification factors 

 from the numerical model and wave measurements at the directional array 

 outside the harbor. They are compared to operational criteria for wind waves 

 and swell. 



Amplification Factors 



Amplification factors, representing directionally spread short wave spectra in 

 the form of (A^j^in Equation 17, were calculated for a variety of wind wave 

 and swell conditions. Figure 48 shows examples of a short period swell and a 

 long period swell coming from two different directions. Tables of (A^^in the 

 existing harbor for various incident peak wave periods and directions (T p and #J 

 are given in Appendix F. 



For a more concise comparison between the existing harbor and alternative 

 plans, average values of (A^^were computed for each basin across wave 

 periods ranging from 10 sec through 20 sec. Figure 49 shows results for the 

 existing harbor and three plans. The (A^^ changes progressively as incident 

 wave direction changes. As would be expected, amplification tends to be greater 

 for directions of more direct approach to the basins. Also it is evident that the 

 proposed new passenger pier locations in these particular plans have an exposure 

 to wind waves and swell which is significantly greater than that at the existing 

 Pier 1 (Basins 4-6). 



As illustrated in Figure 49, the average amplification factor changes between 

 plans only if there are significant changes in basin location (as in the passenger 



Chapter 5 Harbor Response to Wind Waves and Swell 69 



