Calculation of spectra 



Numerical model test results for short waves in Kahului Harbor are all based 

 on spectral post-processing of the initial HARBD runs. Hence, short wave 

 amplification factors are all in the form of (A^^in Equation 17. This approach 

 requires, first, that HARBD be run with the range of wave periods and directions 

 to be considered in the spectral calculations. Second, values of peak wave period 

 T p corresponding to the peak spectral frequency, wave approach direction m , 

 spectral peak enhancement factor y, and directional spreading factor s must be 

 specified. The T p and m values were chosen to represent wind wave and swell 

 conditions at the harbor, as discussed in the section "Incident wave conditions" 

 (pages 61 and 62). 



Values for y and 5 were approximated by relating the guidance in 

 Tables 9 and 10 to T p values. High energy waves, of concern for harbor design, 

 with T p up to 10 sec were assumed to be 

 growing seas. Parameters y and s were set 

 to 3.3 and 10, respectively. Waves with T p 

 greater than 10 sec were treated as swell. 

 As swell T p increases, the swell is 

 expected to have an increasingly peaked 

 frequency spectrum and narrow direc- 

 tional spread. To represent the spectrum 

 for the range of swell considered, values 

 of y and s were scaled to fall between the 

 values for growing seas and maximum 

 values established for old swell 

 (Table 17). 



Output basins 



In order to get special coverage of 

 areas where harbor traffic would most 

 likely be affected by wave conditions, 

 38 possible output locations or "basins" 

 were selected to cover all harbor layouts. 

 A basin is a small cluster of elements over 

 which the HARBD response is averaged 

 to give a more representative output. 

 Whenever possible, basins were posi- 

 tioned to coincide with basins of other 

 plans, particularly those of the existing 

 harbor (Figure 46). Basin locations for 

 alternative plans are given in Appendix E. 

 In general, primary output basins define 

 five areas of interest: Pier 1 (Basins 2-6), 

 Piers 2 and 3 (Basins 7-10), recreational 

 boat ramp (Basin 21), modified barge pier, 

 and proposed passenger pier. Locations 



Table 17 

 Approximate 

 Relationships Among 

 Tp, y, and s 



(sec) 



Y 



s 



8 



3.3 



10 



9 



3.3 



10 



10 



3.3 



10 



11 



4 



15 



12 



4 



20 



13 



5 



25 



14 



5 



30 



15 



6 



35 



16 



6 



40 



17 



7 



45 



18 



7 



50 



19 



8 



55 



20 



8 



60 



21 



9 



65 



22 



9 



70 



23 



10 



75 



24 



10 



75 



Chapter 4 Numerical Model 



63 



