The wave crest elevation of irregular waves on a 1 on 30 slope may also be 

 described in terms of deepwater wave characteristics. An examination of the 

 data indicates that deepwater wave steepness and local Stillwater depth control 

 the magnitude of crest elevation at a given probability level. For example. 

 Figure 23 presents the crest elevation exceeded by 13.5 percent of the wave 

 crests for the deepwater wave steepness range 0.0035 < H^/Lq < 0.0075 for 

 m = 0.0333 (a 1 on 30 slope with the experimental setup shown in Fig. 6). The 

 irregular wave data show a consistent trend with crest elevation increasing in 

 the shoaling region and decreasing after breaking. 



1.5 





« 



1. 







0035 < H( 



3/Lo< 0.0075 







• 



• • 

 • • 



. r 1 



• 



• 



i 



• 



•• : • . 



. • : 



. • 



1 



• 

 • 

















o 1.0 



ZO.5 



I 2345578 



d/Ho 



Figure 23. Wave crest elevation exceeded by 13.5 percent of the wave crests. 



2. Crest Elevation Prediction Aids . 



Irregular wave crest elevations may be predicted in terms of local wave 

 conditions using equation (8). Figure 24 gives crest elevation exceeded by 

 2 percent of the wave crests (p = 0.02) normalized by the water depth. Curves 

 of constant Hg/d are plotted with d/(gT^) on the abscissa. As a first 

 estimate the upper limit of wave height is assumed to be given by equation (5) 

 and the crest elevation of this condition is shown as a dashline. Figure 25 

 presents crest elevations exceeded by 13.5 percent of the wave crests. Figures 

 24 and 25 may be used for waves traveling over a flat bottom and for plane 

 slopes as steep as 1 on 30. 



Crest elevations are presented in terms of deepwater wave characteristics 

 for incident waves normal to a 1 on 30 slope for the 2- and 13.5-percent 

 probability of exceedance levels in Figure 26. These curves were determined 

 using the laboratory data presented in Appendix D, A dashline is used to 

 indicate a region of uncertainty. 



40 



