• 



03 J> 



IN 94 



A 



20 J 



kN94 



■ 



31 J> 



N94 



♦ 



13M 



4R94 



Short waves. Four high wave events during January and March 1994 were 

 selected for short wave calibration (Table 14). HARBD was run for the incident 

 wave periods and directions described in the following section and the output 

 was post-processed to give spectral estimates of the four events. Reflection 

 coefficients were adjusted within reasonable ranges to achieve a good fit between 

 field data and model results (Figure 41). The principal adjustment was the 

 reflection coefficient 

 used along the piers. 

 As-built plans for the 

 commercial piers and 

 laboratory studies of a 

 similar configuration of 

 pile-supported pier 

 with underlying slope 

 (Allsop 1990) were 

 used to determine 

 reasonable ranges for 

 reflection coefficient. 

 Only the 192-, 203-, 

 and 214-deg incident 

 wave directions were 

 used during the calibra- 

 tion and validation 

 phase of the study. 

 The remaining two 

 directions were added 

 later to more 

 completely represent 

 the range of diffraction 

 possibilities for alternatives involving the western portion of the harbor. 



1.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 

 (Aomp.s)horborgoge 



Figure 41. 



Model short wave calibration to four 

 storm events 



Table 14 



Field Cases for Short Wave Model Calibration, Array 



Date 



Hour 



cm 



sec 



deg 



3 Jan 94 



1300 



212 



14.8 



194 



20 Jan 94 



1300 



247 



10.1 



202 



31 Jan 94 



0700 



162 



17.9 



191 



13 Mar 94 



1300 



195 



8.9 



205 



A comparison of HARBD results and field data with published diffraction 

 patterns through a breakwater gap, done as part of the calibration process, 

 showed the dominance of diffraction between the entrance and interior harbor 

 locations. Goda (1985) gives diffraction of a directional spectrum through a gap 

 between two straight, colinear breakwaters in uniform depth. Bowers and 

 Welsby (1982) report on laboratory tests of several other breakwater gap 



Chapter 4 Numerical Model 



57 



