e. Orientation of Wave Gages . In calculating directional wave properties 

 relative to the shoreline, it is extremely important to establish the orienta- 

 tion of the wave gage array and a representative shoreline orientation. During 

 the original study, the locations of the wave gages had been established by 

 measuring angles with transits from two known shore stations on the project base 

 line. These angles were then translated into gage locations through standard 

 geometric procedures. Two sets of such measurements were taken on 24 and 26 

 June 1974. The resulting gage characteristics are presented in Table 3. 



Table 3. Geometric characteristics of the two-gage array. 



Date 



Gage" separation distance 



Gage orientation with 





(m) 



respect to base line 



24 June 1974 



23.55 



10.81° 



26 June 1974 



22.71 



14.44° 



7 June 1980 







Trial 1 



23.8 



15.81° 



Trial 2 



23.2 



12.74° 



Trial 3 



22.6 



12.36° 



Values adopted 







in this study 



23.2 



13.23° 



Although the gage separation distances obtained from the two surveys dif- 

 fered somewhat more than desired, the gage orientations that differed by 3.6° 

 were of particular concern. Thus, on 7 June 1980, these variables were estab- 

 lished using range-range microwave equipment. Measurements were obtained from 

 three combinations of shore-based locations, which allowed a better determina- 

 tion of gage orientation; the results are also presented in Table 3. The average 

 of all values were adopted for the present study. 



f. Effective Shoreline Orientation . The determination of effective shore- 

 line orientation was somewhat more difficult at this site than originally antic- 

 ipated. One difficulty was that dredging and subsequent filling by longshore 

 sediment transport in the impoundment area caused local anomalies in the bottom 

 contours, such that they were not quite straight and parallel. In particular, 

 following a dredging activity, the nearshore contours moved landward more than 

 the seaward contours. This is believed to be an expression of the concentration 

 of the longshore sediment transport in the nearshore zone. 



The shoreline orientation was established by plotting and overlaying pro- 

 files located in the vicinity of the wave gages. The relative landward-seaward 

 locations of the profiles were adjusted in the overlays to obtain best agree- 

 ment by eye and the associated orientation determined. A range of orientations 

 were obtained by matching the nearshore and offshore parts of the profiles. 

 These ranges were qualitatively consistent with those determined from aerial 

 photography, with the larger angles associated with the more seaward parts of 

 the profiles (see Table 4) . 



35 



