Based on the results of the physical coastal model investigation reported 

 herein, the following is concluded: 



a. Existing conditions are characterized by rough and turbulent wave condi- 

 tions in the harbor. Very confused wave patterns were observed because 

 of reflected wave energy off the vertical walls in the harbor. Wave 

 heights of 1.19 m (3.9 ft) were obtained for typical storm conditions 

 (1.22-m (4.0-ft) incident waves); and wave heights of 1.8 m (5.9 ft) were 

 obtained for extreme storm-wave conditions (2.68-m (8.8-ft) incident 

 waves). 



b. Sediment-tracer experiments for existing conditions revealed that shoaling 

 of the harbor entrance will occur for all hydrodynamic conditions studied 

 (i.e., both wave directions, both swls, and both riverflow and no flow 

 conditions). 



c. Experimental results for the initial improvement plans (Plans 1-8) 

 indicated that the breakwater configurations of Plans 6 and 7 were 

 optimum with regard to wave protection in the harbor and the prevention 

 of shoaling in the entrance channel. Results obtained for these 

 configurations were used as a basis for subsequent experiments. 



d. The Plans 9 and 10 breakwater configurations resulted in significant 

 improvements in wave conditions in the harbor relative to existing 

 conditions. Considering all hydrodynamic conditions, wave heights in the 

 harbor were reduced from 31 to 71 percent for Plan 9 and from 34 to 



67 percent for Plan 10. 



e. Sediment-tracer experiments conducted for Plans 9 and 10 revealed that 

 the Plan 9 configuration will provide slightly more shoaling protection of 

 the harbor entrance than that of Plan 10. Both plans, however, are a 

 significant improvement over existing conditions. 



/ The breakwater configurations of Plans 9 and 10 will have no adverse 

 impacts on wave-induced current patterns and magnitudes in the vicinity 

 of the harbor. 



g. Boat wakes for the smaller vessel (27-m- (90-ft-) long) vessel moving at 

 greater speeds resulted in greater wave heights in the harbor for existing 

 conditions as well as Plans 9 and 10. For this vessel, however, wave 

 heights were significantly reduced for Plans 9 and 10 versus existing 

 conditions. The Plan 9 configuration resulted in wave heights slightly 

 less than those of Plan 10. 



h. The breakwater configurations of Plans 9 and 10 will have no adverse 

 impacts on sediment patterns and subsequent deposits along the shoreline 

 downstream of the harbor. 



i. Of the improvement plans consisting of a raised breakwater (Plan 11) and 

 wave absorbers installed in the harbor (Plans 12-16), the absorber of 

 Plan 14 appeared optimum in reducing wave heights in the harbor. 



62 Chapter 7 Conclusions and Recommendations 



