331. Groins . Figure 33 illustrates various legal representations of 

 groins. Simple groins can have arbitrary lengths and are aligned parallel to 

 the y-axis by GENESIS; i.e., angled groins cannot be directly modeled. Groins 

 are assumed to extend a distance landward of -9999 m or ft from the x-axis. A 

 groin cannot be flanked on its landward end; i.e., it cannot be isolated in 

 the surf zone. However, groins can be covered by sand, as may occur during a 

 beach fill; if uncovered by wave action, they will resume functioning. 



20 30 



DISTANCE ALONGSHORE/GRID CELL NUMBER 



Figure 33. Legal placement of simple groins 



Complex Groin Configurations 



332. Complex groin or jetty configurations, such as Y-groins, T-groins, 

 and spur jetties, can be represented by placing tips of diffracting groins and 

 detached breakwaters together. Figure 34 shows examples of complex structure 

 configurations that may be represented, and Table 3 shows the corresponding 

 values defining these configurations in the START file. 



143 



