PART III: ASSESSMENT OF DESIGN TECHNIQUES 

 Introduction 



43. To evaluate the empirical design methods presented in Part II, data 

 from five US breakwater projects have been compiled (Table 1) and prototype 

 response compared with that predicted by the relationships. Variables 

 presented in Table 1 are defined in Appendix A. These projects encompass a 

 range of structural and site parameters and observed beach response, from 

 salient formation (Lakeview Park and Redington Shores) , to no beach response 

 (Lakeshore Park) , and periodic tombolo formation (Colonial Beach, Central and 

 Castlewood Park Beaches) . 



Evaluations 



Morphological response 



44. Two types of predictive relationships were discussed that relate to 

 morphological response: those that predict a nondepositional , salient, or 

 tombolo response as a function of structural parameters; and a relationship 

 predicting seaward salient excursion. By far, the majority of the relation- 

 ships presented fall into the first category; an evaluation of these relation- 

 ships by author is presented in Figure 10. Dashed horizontal lines in the 

 figure separate the boundaries between the indicated morphological responses; 

 solid lines indicate the range recommended by the cited author. 



45. A trend is apparent in the prototype data for deposition to 

 increase as the structure length to distance offshore ratio increases. 

 However, the ability of the relationships to accurately predict observed 

 response is at best fair. If other types of design tools are available, it is 

 recommended that these simple empirical relationships be used only as a 

 general guide when designing a project. 



46. Suh and Dalrymple's (1987) relationship for salient length (Equa- 

 tion 42) was applied to all segmented projects (Equation 42 does not apply to 

 single structures since gap distance Lg is not defined) . The relationship 

 tends to overpredict the seaward excursion of the spit for the majority of 

 prototype data evaluated (Figure 11) , but appears to predict very well for the 



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