Spectra for the 24 highest energy cases from each gage were stumna- 

 rized individually. Many of the spectra had more than one major peak. 

 Although many of the high-energy cases represent breaking wave condi- 

 tions, the ratio of significant height to water depth was less than 0.55 

 in all cases. This value differs significantly from the value 0.78 which 

 is usually used in conjionction with depth- limited wave heights. 



All spectra were grouped according to significant height and period 

 corresponding to the highest spectral peak. A mean spectrum was com- 

 puted for most height -period groiqjs. The standard deviation of spectral 

 values about the mean was also included. The mean spectra show a clear 

 lack of low-frequency energy at the gulf and Great Lakes sites and a 

 lack of high-frequency energy at the southern California site. They also 

 show evidence of systematic variations in shape as a function of signifi- 

 cant height and peak period. 



Multipeaked spectra are common; 60 to 70 percent of the ocean and 

 gulf coast spectra and at least 50 percent of the Great Lakes spectra 

 have more than one major peak. Major spectral peaks are usually indica- 

 tive of independent wave trains. 



High values of the spectral-peakedness parameter appear to be related 

 to the occurrence of high waves in groins. However, low values of the 

 spectral-peakedness parameter are not necessarily indicative of a lack 

 of grouping of high waves in shallow water. The distribution function of 

 sea-surface elevations in shallow water tends to deviate from a normalized 

 Gaussian distribution in a way which is consistent with cnoidal-type wave 

 profiles. 



In the course of this investigation, a computer program was developed 

 to identify major peaks and valleys in an irregular signal. The program 

 has many potential applications, including identification of major peaks 

 in a spectrum and identification of meaningful crests and troughs in a 

 time series of sea-surface elevation. 



57 



