Fully 3D models 



Fully 3D-beach change models represent the state-of-art of research. 

 Waves, currents, sediment transport, and changes in bottom elevation are 

 calculated point by point in small areas defined by a horizontal grid placed 

 over the region of interest. Use of these models requires special expertise, 

 powerful computers, and extensive field data collection programs (Vemulakonda 

 et al . 1988), and applications have been limited to large and high-funded 

 projects. Because fully 3D-beach change models involve the detailed physics 

 of sediment transport, they require extensive verification and sensitivity 

 analyses . 

 Summary of model capabilities 



Only two types of well tested beach change numerical simulation models are 

 presently available for general use, namely, the storm- induced beach erosion 

 model and the shoreline change model. The storm erosion model is site specif- 

 ic in that local profile information and storm statistics are the main inputs. 

 This type of model is discussed in a deterministic approach by Larson and 

 Kraus (1989) and in a statistical approach by Scheffner (1989) in papers 

 companion to this one. 



The shoreline change model requires comprehensive data on the local and 

 regional levels. Therefore, it is an ideal vehicle for systemizing the 

 planning process for coastal protection, and the remainder of this paper will 

 deal with this model. Examples illustrating shoreline change model capabili- 

 ties are given in companion papers by Gravens (1989) and Hanson, Kraus, and 

 Nakashima (1989), and Hughes (1989). 



The shoreline change numerical model simulates long-term evolution of the 

 beach plan shape and provides a framework to perform a time -dependent sediment 

 budget analysis. As such, its operation and output are readily understood by 

 coastal engineers and managers. The model is robust in that it can describe a 

 wide range of conditions encountered in shore protection projects. The 

 Coastal Engineering Research Center of the U.S. Army Engineer Waterways 

 Experiment Station is in the final stages of releasing the model GENESIS 

 (GENEralized model for Simulating Shoreline change) (Hanson 1987, 1989, Hanson 

 and Kraus 1989) for widespread use in the Corps of Engineers. Much of the 



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