1 



f 



\ 1 





a = O 





1 









1 









1 

















DETACHED 

 BREAKWATER 



J 





V//////////X/////////A 







i 



1 , 



\ 







~- +-»_^ 









i T — „ 







or 02 =0 



I ^Tr^- 







i J~*- 



—^01 









1 f 



i 



1 1 



| 



^- 



-2L 



-L 



Figure 35. Definition sketch for the problem of shoreline change in 

 the vicinity of a detached breakwater 



76. Since the incident breaking wave angles and the amplitudes of the 

 sand transport rates 



shadowed and illuminated regions, a coupled problem arises, 

 conditions for this case are as follows: 

 a. 



Q , respectively, are different in the 



The boundary 



No sand should be transported across the line of symmetry 

 behind the breakwater. 



b. The sand transport rate out of the area on the right side of 

 the breakwater should be equal to that into the area behind the 

 breakwater. 



c. The shoreline is continuous over the boundary between the two 

 areas. 



Furthermore, the shoreline should be undisturbed (y = 0) far from the struc- 

 ture. With y. denoting the shoreline position in solution area number 1 

 (shadow region) and y„ denoting the shoreline position in solution area num- 

 ber 2 (the illuminated region) , the mathematical formulation of the situation 

 is 



56 



