Methods developed in this report are illustrated by using the observed 

 conditions from one gage to predict wave heights at other locations along the 

 pier. For the December 1977 storm, the gage on the end of the pier at station 

 580 meters was used to predict significant wave heights at station 190 meters 

 (Fig. 4), and observed and predicted waves were compared throughout the storm 

 (other gages were not in operation) . For the September 1978 storm, a wave 

 gage 2,250 meters beyond the end of the pier was used to predict the significant 

 wave height at points along the entire pier length. Observed and predicted wave 

 conditions were then compared. 



Or 



10 



Woter Depth, d MSL (m) 



Survey Dole 



18 Dee. 1977 

 8 Sept. 1978 



Station 

 Along 

 Pier (m) 



190 240 325 430 580 



1.8 - - ~ 7.9 



0.9 4.6 5.1 6.6 8.8 



Offshore Goge 

 2,250 meters 

 off end of pier 



Figure 4. 



4.6 5.1 6.6 



Profile at the Field Research Facility. 



The beach slope is approximately 1/80 at the FRF, so a diagram of the 

 nearshore significant wave height was prepared, similar to the curves in Appen- 

 dix C (Fig. 5). 



The observed tide, wave period of the highest one-third waves, T s , and 

 the significant wave height, H s (defined as four times the standard devia- 

 tion of the wave record) are given in Figure 6 for the December 1977 storm. 

 Visual observations suggested that the wave angle at the end of the pier was 

 small, so a was taken as 0.0°. Since the waves were short-crested (Fig. 7), 

 S* = 4 was selected. A prestorm survey indicated that the water depth below 

 mean sea level was 7.9 meters at the end of the pier and 1.8 meters at station 

 190 where predictions of significant wave height were made using Figures 5 and 

 A-3 with the observed conditions at the end of the pier. Observed (solid line) 

 and predicted significant wave heights (symbols) show agreement, especially 

 during the highest wave conditions (Fig. 6). Tidal variation in water levels 

 is associated with wave height changes and this is clearly shown in observed 

 and predicted wave heights (not shown in observations at station 190 during 

 the end of the storm due to sparse observations) . 



For the 13 September 1978 storm, a wave gage 2,250 meters beyond the end 

 of the pier was used to record offshore wave height and period. Radar images 

 were used to estimate dominant wave direction. Predicted tides and a profile 

 survey of 8 September 1978 were used to determine water depth along the pier. 

 Figure 8 shows nearshore wave conditions. 



