study to assess and refine alternatives; and finally, if time and funding 

 allow, a prototype test to verify and adjust the preliminary design. Initial 

 use of empirical design methods can also provide a means of assessing model 

 performance. Numerical and physical models, once calibrated and verified, can 

 be used to extend and improve empirical relationships. Prototype assessment 

 of a design alternative can provide data for refinement of empirical relation- 

 ships and model calibration/verification. 



10. The design methods that will be presented and evaluated herein are 

 various empirical relationships for iterative use throughout the project 

 design. These relationships include those that have been used to design US 

 and foreign detached breakwater projects, and those recently developed through 

 prototype and physical model evaluation. 



Empirical Relationships 



Introduction 



11. Prior to utilizing techniques for any type of structure design, the 

 functional intent of the project must be well-defined. Parameters such as the 

 length of shoreline to be protected, design beach width, and acceptable 

 adjacent beach erosion/accretion should be delimited. A breakwater project 

 can be designed in segments, to protect a long length of shoreline, for 

 salient or tombolo formation, or both. In the case of a site with a sig- 

 nificant longshore transport rate adjacent to beaches that cannot tolerate 

 much project- induced beach change, the design beach response should be a 

 salient. A salient allows littoral movement of material to continue shoreward 

 of the structures, minimizing project impacts on adjacent shores. If impacts 

 to adjacent beaches are not of concern, the breakwater system could be 

 designed for tombolo formation, maximizing project beach accretion. A common 

 nomenclature for all relationships will be used throughout this report and is 

 presented in Figure 1. All variables used throughout the report are defined 

 in Appendix A. 



12. The empirical relationships presented herein are generally orga- 

 nized from the simpler to more complex design techniques and comprise a review 

 of all studies that have recommended empirical relationships or methods for 

 the design of breakwater systems. A general review of detached breakwater 



