structure of Plan 22 will meet the established wave-height criterion 

 for design wave conditions from all directions. Maximum wave 

 heights of 6.0 ft will exist in the entrance for waves from the 

 predominant west-northwest direction. 



/. Of the improvement plans involving two inner detached breakwaters 

 (Plans 23 through 26), the 375-ft-long north structure and 

 250-ft-long south breakwater (Plan 26) will meet the established 

 wave-height criterion in the entrance for design wave conditions 

 from all directions. Wave heights in the existing entrance will be 

 up to 5.8 ft for waves from the predominant west-northwest 

 direction. 



Subsequent to testing of the supplemental tests, a conference was held 

 at the U.S. Army Engineer Waterways Experiment Station (WES) Coastal 

 Engineering Research Center (CERC) with representatives in attendance 

 from Noyo Harbor, the U.S. Army Engineer Division, South Pacific 

 (CESPD), and the U.S. Army Engineer District, San Francisco (CESPN). 

 Wave height tests were conducted for an outer offshore breakwater config- 

 uration provided by CESPN. Breakwaters were constructed expeditiously 

 with mixed stone, and wave height tests were conducted for 1 1 test plan 

 configurations (Bottin 1989). A plan which included a 400-ft-long struc- 

 ture located in the cove approximately 2,000 ft from the river entrance 

 looked promising; however, test results indicated there would be periods 

 when 14-ft-high incident waves would exceed the 6.0-ft criterion and 

 break in the entrance. 



Purpose of the Current Investigation 



The Noyo River and Harbor model was reactivated at the request of 

 CESPN to refine the design of the 400-ft-long offshore structure tested 

 during the 1989 conference. A breakwater with the appropriate transmis- 

 sion characteristics was installed and subjected to a wide range of wave 

 conditions. The impact of the structure on long-period wave conditions in 

 the harbor and on wave-induced and riverine bed-load sediment patterns 

 also was evaluated for the optimized structure. 



Wave-Height Criterion 



Completely reliable criteria have not yet been developed for ensuring 

 satisfactory navigation and mooring conditions in small-craft harbors dur- 

 ing attack by waves. For this study, however, CESPN specified that for an 

 improvement plan to be acceptable, maximum significant wave heights 

 were not to exceed 6.0 ft in the existing Noyo River jettied entrance for in- 

 cident wave heights of 14 ft or less. 



Chapter 1 Introduction 



