The harbor wave response model is presented in the following section, 

 including a general description of the HARBD model and implementation of the 

 model at Kahului Harbor. Validation was accomplished with a combination of 

 storm wave events selected from available field data and with statistical sum- 

 maries of a wide range of field cases. The final section of this chapter describes 

 the test procedures and calculations. Procedures for evaluating operational 

 performance at a pier are discussed. 



As part of the test procedures, a suite of incident wave conditions must be 

 specified at the seaward boundary of the area covered by HARBD. Incident 

 short waves are determined by consideration of measurements outside the harbor. 

 Incident long waves are specified over a broad range of frequencies but only a 

 normally incident direction to identify possible harbor resonant responses. 



The existing harbor and 1 1 proposed modifications were studied. Results for 

 wind waves and swell are presented in Chapter 5. Harbor oscillation results are 

 presented in Chapter 6. The presentation focuses on wave conditions in the 

 vicinity of existing or proposed piers, but results over the full harbor area are 

 also given. 



Model Description 



Model formulation 



The numerical wave model HARBD is a steady-state hybrid element model 

 used in the calculation of linear wave response in harbors of varying size and 

 depth (Chen 1986, Chen and Houston 1987, Lillycrop and Thompson 1996). 

 Originally developed for use with long-period waves (Chen and Mei 1974), 

 HARBD has since been adapted to include capabilities for modeling wind waves 

 and swell (Houston 1981), bottom friction, and partially reflective boundaries 

 (Chen 1986). The model is based on a linearized mild slope equation. An 

 overview of the model and its applications is given by Thompson and Hadley 

 (1995). 



The HARBD model has been shown to perform satisfactorily in comparison 

 to analytic solutions and laboratory data for a variety of wind wave and swell 

 cases (Houston 1981; Crawford and Chen 1988; Thompson, Chen, and Hadley 

 1996) and long wave cases (Chen 1986; Chen and Houston 1987; Houston 1981; 

 Thompson, Chen, and Hadley 1993). As a result, it has been used with confi- 

 dence in both long wave and short wave studies. Studies encompassing both 

 long (harbor oscillations) and short waves are Harkins et al. (1996) and 

 Thompson and Hadley (1994b). Additional long wave studies have included 

 harbor oscillations (Briggs et al. 1994; Briggs, Lillycrop, and McGehee 1992; 

 Mesa 1992; Sargent 1989; Weishar and Aubrey 1986; Houston 1976) and 

 tsunamis (Farrar and Houston 1982, Houston and Garcia 1978, Houston 1978). 

 Additional wind wave and swell studies include Thompson and Hadley (1994a); 

 Lillycrop et al. (1993); Lillycrop and Boc (1992); Lillycrop, Bratos, and 



42 



Chapter 4 Numerical Model 



