3 Tools for Prediction of 

 Morphologic Response 



50 



Introduction 



The knowledge base and engineering experience essential for coastal proj- 

 ect design is developed from information on project evolution, response of 

 other projects with similar coastal processes, and empirical relationships. 

 From this framework, the design engineer refines the project goals and limita- 

 tions, and identifies types of solutions that may be feasible at the site. 

 Numerical and/or physical model simulation is recommended for further 

 assessment of these design alternatives. Use of numerical and physical models 

 facilitates unbiased evaluation and optimization of alternatives, as well as 

 providing a structure that assists in directing data collection and analysis. The 

 purpose of this chapter is to discuss numerical and physical modeling as 

 applied to detached breakwater design, provide general guidelines for conduct- 

 ing these studies, and present examples of model use with prototype detached 

 breakwater projects. 



Numerical Models 



Overview 



Beach change numerical models use sediment transport relationships and 

 conservation of volume to simulate beach response to various driving forces 

 (e.g., waves, currents, and water levels). There are two types of well-tested 

 beach change models: short-term (hours to days) storm-induced profile 

 prediction, and long-term (months to decades) shoreline response models 

 (Kraus 1990). 



Correct application of a storm-induced beach profile change model requires 

 the assumption that longshore transport is constant for the project reach, and 



Chapter 3 Tools for Prediction of Morphologic Response 



