based on 20-year hlndcast. This Information was in the form of frequency of 

 occurrence of waves in terms of predominant direction, significant wave 

 height, and period bands in a depth of 60 ft mlw. Table 2 shows a sample of 

 WESWIS data for St. Marys Inlet. The wave approach angle notation in this 

 table is different from that used in the rest of this report. Angles in the 

 table are measured with respect to the shoreline. Consider waves with an ap- 

 proach angle of 70.0 to 79.9 deg and significant wave heights in the band 0.0 

 to 0.49 m. They are distributed in period bands between 0.0 to 11.0 sec and 

 greater. The total frequency of occurrence of these waves summed over all the 

 period bands is 3.515 percent (3,515 ■^ 1,000) or 0.03515. Similarly, WESWIS 

 provides wave information in direction bands of 10 deg from to 180 deg for 

 all the wave height bands (0 to 5.00 m and greater). 



91. In this study, these data were further consolidated into 79 differ- 

 ent incident wave conditions (combinations of significant wave height, period, 

 and direction) to run the wave and wave-induced current models. For conve- 

 nience in running the sediment transport model, wave condition 80 was defined 

 as a null wave condition when there was no significant wave activity. These 

 combinations are listed in Table 3 which shows the percentage of occurrence of 

 each condition. The directions represent angles in degrees measured from azi- 

 muth 87.5 deg (approximate shore normal direction). Negative angles signify 

 waves coming from directions south of the normal; positive anglds signify 

 waves coming from directions north of the normal. The wave combinations shown 

 in Table 3 are obtained from Table 2. Consider the example from Table 2 

 again. Since the wave approach angle is between 70.0 and 79.9 deg, the aver- 

 age value of 75.0 deg is taken. In terms of the notation of Table 3, the wave 

 direction becomes -12.5 deg. Since the wave height band is from 0.0 to 



0.49 m, the mean value of 0.25 m or 0.82 ft is taken for the significant wave 

 height. As for period, on the basis of the distribution of Table 2, a mean 

 period of 8.0 sec is taken. These are the values shown for wave 28 in 

 Table 3. 

 Jetties 



92. To account for diffraction of waves due to the two jetties of 



St. Marys Inlet, a special subroutine was developed. It used the diffraction 

 solution of Penney and Price (1952). The wave model was first run without 

 accounting for the presence of the jetties. The diffraction subroutine took 

 the solution near the jetties as input and modified it to allow for 



51 



