Other Considerations 



57. There are several other factors which can affect detached break- 

 water design. These considerations include (a) ecology, (b) aesthetics, 

 (c) return flow through breakwater gaps, (d) beach user safety, (e) naviga- 

 tion, and (f) construction. Structural aspects such as foundation design, 

 scour protection, cross-section shape, and stone sizing and placement are not 

 discussed in this report. Information on these design aspects can be found in 

 Chapter 7 of the SPM. 



Ecology 



58. The design analysis of detached breakwaters should include an ap- 

 praisal of the environmental impact of the project. Rounsefell (1972) dis- 

 cusses the ecological effects of offshore construction and Thompson (1973) 

 examines the ecological effects of offshore dredging and beach nourishment. 

 While these studies suggest that detached breakwaters generally should not 

 cause long-term undesirable ecological changes, each proposed project site is 

 unique and must be examined for possible negative impact to the ecological 

 system. 



59. An ecological concern that has been associated with detached 

 breakwaters in countries such as France and Israel is the effect of reduced 

 circulation on water quality. If wave transmission over or through the 

 structure is too limited, the exchange of water in the embayments can be re- 

 duced significantly, raising the possibility of the entrapped water becoming 

 stagnant and unhealthy. Regions where water level variations are small may be 

 especially susceptible to this problem. Making the breakwater gaps larger or 

 more numerous may increase the water circulation in segmented structures. 

 Aesthetics 



60. If a breakwater is to be constructed to protect a recreational 

 beach, aesthetics should be considered. Bathers sitting on the beach like to 

 see the horizon, and the height of the breakwater may need to be reduced ac- 

 cordingly. This can influence the structural design by increasing wave over- 

 topping. Reducing permeability, increasing structure length, and reducing gap 

 size for segmented breakwaters are ways to compensate for the increase in 

 energy transmission due to overtopping. Some areas may have a particular 

 aesthetic appeal because of high surf. Breakwaters reduce that aesthetic 

 value, which may be perceived as a disadvantage. 



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