182 deg, and through the breach in the new breakwater for waves from 182 and 

 137 deg. Maximum velocities were 1.34 mps (4.4 fps) adjacent to the west side of 

 the causeway; 1.86 mps (6. 1 fps) through the breach in the causeway; 0.46 and 

 0.61 mps (1.5 and 2.0 fps) along the inner and outer causeway docks, respectively; 

 and 0.40 mps (1.3 fps) in the new entrance channel for 12-sec, 5-m (16.4-ft) waves 

 from 227 deg; and 2. 13 mps (7.0 fps) adjacent to the east side of the new break- 

 water; 2.26 mps (7.4 fps) through the breach in the new breakwater; and 0.79 mps 

 (2.6 fps) along the shoreline between the new breakwater and the existing entrance 

 for 12-sec, 5-m (16.4-ft) waves from 137 deg. 



The general movement of tracer material for 5- and 6-m (16.4- and 19.7-ft) 

 waves from 227, 182, and 137 deg is shown in Plates 81-86 for Plan 19. For waves 

 from 227 deg, sediment along the shoreline west of the causeway moved east toward 

 the structure. The extreme wave conditions (12-sec, 6-m (19.7-ft) waves) resulted 

 in material moving through the breach in the causeway and depositing in the 

 deposition basin. For waves from 182 and 137 deg, this material tended to split, 

 with some moving westerly and some moving easterly toward the causeway. 

 Sediment did not move through the breach in the causeway for these directions. 

 Tracer material adjacent to and west of the causeway moved seaward and around the 

 head of the structure for waves from 227 deg; but for waves from 182 and 137 deg, 

 tracer tended to split with some migrating seaward along the causeway and some 

 moving northerly along the structure. Sediment along the shoreline east of the new 

 breakwater and west of the existing entrance generally moved shoreward and then 

 westerly for waves from all three directions, though a slight amount of easterly 

 movement was noted for some conditions. In addition, sediment adjacent to and 

 east of the new breakwater about midway generally moved northerly for waves from 

 227 and 182 deg and seaward for waves from 137 deg, while sediment in the 

 vicinity of the head of the new structure moved seaward for waves from all three 

 directions, with a slight amount moving northerly for waves from 227 and 182 deg. 



Discussion of experimental results 



Results of wave height experiments for existing conditions indicated rough and 

 turbulent wave conditions in the existing entrance as well as along the existing 

 causeway docks. Wave heights in the entrance exceeded 1.5 m (5 ft) for typical 

 storm wave conditions (2-m (6.6-ft) waves). In addition, very confused and 

 turbulent wave patterns were observed in the entrance due to reflected wave energy 

 off the vertical walls. Wave heights along the existing outer and inner causeway 

 docks were in excess of 3.7 and 2.7 m (12 and 9 ft), respectively, for typical storm 

 wave conditions. For 50-year storm conditions (6-m (19.7-ft) waves), wave heights 

 obtained in the entrance were almost 3.7m(12ft)in height and wave heights along 

 the outer and inner docks were almost 7.0 and 5.8 m (23 and 19 ft), respectively. 



Preliminary experiments conducted with expeditiously constructed improvement 

 plans (Plans 1-15) proved very beneficial in providing model data in an efficient 

 manner. The lengths and alignments of the new breakwater and causeway extension 

 were preliminarily determined relative to wave heights obtained in the harbor. 

 These improvement plans also indicated the impacts of the structures on wave- 



Chapter 4 Experiments and Results 



33 



