breakwater installed. In general, considering all test conditions, riverine 

 sediment deposited in an area in the cove between the existing Noyo River 

 jetties and the proposed structure location, whether the breakwater was in- 

 stalled or not. 



A comparison of wave-induced sediment tracer tests for existing condi- 

 tions and the offshore breakwater plan reveals that the breakwater had lit- 

 tle effect on tracer patterns and subsequent deposits for test waves from 

 northwest. For test waves from southwest, however, the breakwater re- 

 sulted in a slight shift of the tracer path as it entered the cove. The break- 

 water prevented the material from penetrating as deeply shoreward into 

 the cove as it did under existing conditions. 



Long-period wave tests 



Long-period (60 to 200 sec) wave tests were conducted during previous 

 studies (Bottin, Acuff, and Markle 1988) for existing conditions using 

 waves from the west direction with a +7.0- ft swl. The gage arrangement 

 for these tests is shown in Plate 13. To ensure accurate determination of 

 incident wave height, the first 10 gages were placed in an array at the 

 river entrance to measure nodes and antinodes of possible standing waves. 

 The incident wave height was then calculated from the following relationship: 



H_ + H 



H. = 



where 



H t = incident wave height 



H a = wave height at antinode 



H n = wave height at node 



Test results obtained with the gage array were used to determine incident 

 wave heights in the entrance and corresponding wave-machine stroke set- 

 tings. During the tests, squares of styrofoam confetti were spread over the 

 water surface and observed over the 60- to 200-sec period range. Areas of 

 maximum horizontal movement (nodes) and minimum horizontal move- 

 ment (antinodes) were identified through this series of visual observa- 

 tions. Wave gages were placed in antinodal areas. Measured wave 

 heights at a particular gage location were divided by the incident wave 

 height for that period to obtain the response factor or R = H/H-. Fre- 

 quency response (response factor versus wave period) curves were subse- 

 quently plotted for Gages 1 1-20. 



Frequency response curves for existing conditions are shown in 

 Plates 14-23. These test results indicate that resonant peaks (with amplifi- 

 cation factors in excess of 1 .0) will occur at various stations in Noyo 



Chapter 4 Tests and Results 



25 



