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Figure 1. 



Time — ^ 



Significant wave height = 1.96 m 

 Period of peak energy density = 14 s 

 Water depth (approximately) = 6 m 



Example of an extremely nonlinear wave condition 

 (recorded by a CERC continuous-wire staff at Lake 

 Worth, Florida, 28 March 1971 at 0820). 



provide an upper limit or conservative estimate of crest elevations correspond- 

 ing to various probabilities of exceedance. Actual irregular wave data have 

 crests that are higher than given by this theory, so Jahns and Wheeler (1973) 

 suggest an empirical correction factor. One limitation of the correction 

 factor is that the observed probability of exceedance may deviate several or 

 many orders of magnitude from the Rayleigh distribution. 



Dean (1974) developed one of the most comprehensive theories to date for 

 predicting properties of monochromatic waves traveling over a flat bottom. 

 This higher order stream-function theory can be used to predict crest elevation 

 and duration for a wide range of wave and water level conditions. The theory 

 indicates that in the Airy limit, where the wave amplitude approaches zero, 

 the wave crest elevation is approximately equal to one-half the wave height 

 and the duration of the crest is half the wave period. In the cnoidal wave 

 limit the crest elevation approaches the wave height and the duration of the 

 crest becomes small compared to the wave period. Figure 2 is an example 

 predicted water level time history for a highly nonlinear wave. In this 

 extreme condition the ratio of crest elevation, r\^, to wave height, H, is 

 ri(,/H = 0.90. The duration of the crest, T„, is one-fourth the wave period, 

 T, or T„/T = 0.25. 



Singamsetti and V/ind (1980) presented wave crest characteristics for 

 monochromatic laboratory wave conditions at the point of breaking for constant 

 beach slopes, m, of 1 on 40, 1 on 20, 1 on 10, and 1 on 5. 



