s 



Detached Breakwaters 



Salient 



Initial Shoreline 



Fig. 1. Schematic of shoreline change behind detached breakwaters 



does not reach the breakwater. This allows sand to be transported alongshore 

 between the structure and the beach and to reach downdrift beaches, yet the 

 shore remains protected at the site. In some situations, headlands produced 

 by tombolo development may be the design aim. Pope and Dean (1986) provide 

 empirical guidance based on the functioning of detached breakwaters in the 

 United States, permitting an estimate to be made as to whether a tombolo or 

 salient will form, or if no shoreline change will occur (see also, Suh and 

 Dalrymple, 1987). It is expected that (1) placement closer to the shore will 

 promote tombolo development, (2) longer breakwaters will promote tombolo 

 development, and (3) greater wave transmission will inhibit tombolo devel- 

 opment. 



Essentially all detached breakwaters built for shore protection transmit 

 wave energy by (1) wave passage over the structure, called overtopping, during 

 times of relatively high water level and/or high waves, and (2) wave passage 

 through the structure (depending on the composition of the breakwater). Here, 

 these two processes will be collectively referred to as "wave transmission." 



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