Structure orientation 



56. Orientation of the breakwater with respect to both the predominant 

 wave direction and the original shoreline can affect the size and shape of the 

 resulting salient (s). A change in structure orientation changes the diffrac- 

 tion pattern at the shoreline and subsequently the equilibrium planform con- 

 figuration. The general shape of a salient with incident waves normal to the 

 shoreline can be estimated by determining the configuration of the diffracted 

 wave crests (Chapter 2 of the SPM) . It may be advisable to orient the struc- 

 ture parallel to the incoming wave crests when the local predominant incident 

 waves are oblique to shore. A longer stretch of shoreline will be protected 

 per length of structure, and toe scour at the breakwater head sections will be 

 reduced. The quantity of material required to build the breakwater may in- 

 crease if one end is located in deeper water instead of being oriented paral- 

 lel to the bottom contours. Figure 22 illustrates the effect of structure 

 orientation on shoreline configuration. 



EXPECTED SHORELINE RESPONSE 



ORIGINAL SHORELINE. 



:±^ri77/7>77}^/»^ : ^ 



INCIDENT WAVES 

 NORMAL TO SHORE 



Figure 22. Effect of structure orientation on salient 



47 



