Table 4.4 



Nearshore Wave Statistics for Incident Time Series and Related 



Parameters with Structure in Place | 



Wave 



Toe 

 Depth 



cm 



Wave 

 Height 



cm 



Period 

 sec 



Stability 

 Number 

 N,=HJAD 



Iribarren 

 Parameter 



Period 



7-1/3 

 sec 



Wave 

 Height 



cm 



Period 



•lAlO 



sec 



Wave 

 Height 



"1/10 



cm 



Stability 

 Coefficient 



1 



11.9 



9.38 



1.76 



1.6 



0.36 



2.16 



12.8 



2.28 



11.5 



3.4 



2 



11.9 



11.6 



1.69 



1.9 



0.31 



2.13 



15.4 



2.40 



13.8 



6.0 



3 



11.9 



13.2 



1.74 



2.2 



0.30 



2.22 



17.3 



2.53 



15.7 



8.8 



4 



15.8 



10.1 



1.73 



1.7 



0.34 



2.15 



14.3 



2.31 



12.7 



4.7 



5 



15.8 



13.0 



1.67 



2.2 



0.29 



2.16 



17.8 



2.39 



16.0 



9.3 



6 



15.8 



14.9 



1.66 



2.5 



0.27 



2.20 



19.3 



2.47 



18.0 



13.2 



For a Rayleigh distribution of wave heights, HyJH, = 1.27 and HjJH^ = 

 1.40. Computing these ratios using the values from Table 4.4, HyJH^ = 1.19-1.26 and 

 ^2%/^s = 1.30-1.42, indicating the slight reduction of wave heights due to wave 

 breaking. 



Traditionally, the incident waves are measured without the structure in place 

 (Hughes 1993). For this study, the waves in the flume were measured both with and 

 without the structure in place. For the condition with no structure in place, an array of 

 three gages was placed with its centroid at the location of the structure toe for 

 calibration purposes. The wave gage array was moved to the location shown in Figure 

 4.5 when the structure was in place. Wave heights measured without the structure in 

 place were smaller than those measured with the structure in place, and the difference in 

 H„„ ranged from 6 to 24 percent. The difference between the two sets of measurements 



69 



