2. Waves 



During the 27 months of study, wave data were collected daily at 

 various locations (see Fig. 2 and App. H) and included wave period (in 

 seconds], wave height (in feet), and wave direction (degrees). Wave 

 data were also taken at each monthly surveying session. 



Inspection of the data showed that often there was significant 

 variance between locations in data taken on the same days, most notably 

 in wave periods. This variance is believed to be due to a human 

 factor rather than dramatic shoreline variations in wave periods. 



Table 12 represents a compilation of the daily volunteer wave 

 observer data organized according to location and season. It is 

 apparent that there is too much variance in the data and too few 

 locations to organize the data according to beach type (e.g., commer- 

 cial versus natural beaches) and to attempt any detailed analyses. 

 In organizing the data by seasons it appears that the largest wave 

 heights occur in the summer months and the lowest wave heights in 

 the spring and winter, while the longest wave periods seem to occur 

 during the summer. Most of the storms surveyed occurred during the 

 fall and spring. However, these wave data vary widely between 

 observers (especially wave periods) , and the seasonal differences 

 for most observers are probably statistically nonsignificant. 



Figures 19 and 20 are compiled from wave observations made at 

 each surveying session. The plots represent average breaker height 

 and average wave period plus or minus one standard deviation, for 

 each of the 18 survey locations. These data were taken during non- 

 storm conditions at 1-month intervals and during different stages 

 of the tide and time of day. Average breaker height (Fig. 19) appears 

 to have a slight trend of increasing wave height to the south (0.8 

 plus or minus 0.3 meter at the south end and 0.6 plus or minus 0.3 

 meter at the north end) , which would correlate with the narrowing 

 of the Continental Shelf to the south. This trend is missing from 

 average wave period (Fig. 20), which appears to show more variation 

 between locations. 



Wave refraction and the effect the resulting nonuniform shoreline 

 wave energy concentration has on beach behavior, are presented in 

 refraction diagrams in Goldsmith, et al. (1974b) and the Virginian 

 Sea Wave Climate Model Data Bank at VIMS. In summary, the shoreline 

 wave energy distributions for this area correlate well with the 

 observed beach changes. Specifically: 



72 



