Distance Between Groins: I L 





*\ 



Distance Between Groins: qq 



Figure 5. Two-line theory solution for a groin system 

 (after Bakker 1968) 



theories are also presented. Bakker (1970) developed a phenomenological dif- 

 fraction routine for one-line theory but numerically solved the problem. 



25. Le Mehaute and Soldate (1977) present a brief literature survey on 

 the subject of mathematical modeling of shoreline evolution. Analytical solu- 

 tions of the linearized shoreline change equation are discussed together with 

 the spread of a rectangular beach fill. In Le Mehaute and Soldate (1978, 

 1979) a numerical model is derived which includes variation in sea level, wave 

 refraction and diffraction, rip currents, and the effects of coastal struc- 

 tures in connection with long-term shoreline evolution. 



26. Until recently, the most complete summary of analytical solutions 

 to the sand transport equation has been made by Walton and Chiu (1979). Two 

 derivations of the linearized shoreline change equation are presented together 

 with another approach resulting in a nonlinear model. The difference between 

 the two approaches, which both arrive at the diffusion equation, is that one 

 uses the Coastal Engineering Research Center (CERC) formula (SPM 1984, Chap- 

 ter 4) for describing the longshore sand transport rate by wave action and the 



15 



