be placed at Line D.l, and no other questions beginning with the letter D need 

 to be answered. (If is placed at Line D.l, Lines D.3-D.5 will not be read 

 by GENESIS, and values remaining there may be arbitrary.) 



254. Line D . 3 : NNDG Enter the number of nondiffracting groins and 

 jetties NNDG located on the grid. This number also includes structures that 

 may serve as a groin boundary condition on one or both lateral ends of the 

 grid. 



255. Line D.4: IXNDG(I) Enter the grid cell numbers of nondif- 

 fracting groins and jetties IXNDG(I) in order of increasing cell number. 

 The number of grid cell locations given here should equal the number of 

 nondiffracting groins specified at Line D.3 (NNDG values). 



256. Line P. 5: YNDG(I) Enter the lengths of the nondiffracting 

 groins and jetties YNDG(I) (as measured from the x-axis to the seaward tip 

 of the structure) in the order of cell number in which they occur (NNDG 

 values in increasing order of cell numbers corresponding to the locations 

 given at Line D.4). 



E. Diffracting 

 groins and jetties 



257. Line E.l: IDG If there are long jetties and long groins on 

 the grid (i.e., structures that extend past the breaking wave zone and into 

 relatively deep water for almost all wave conditions), they should be treated 

 as diffracting structures and the value 1 ("yes") placed here in the flag 

 IDG . If there are no such structures on the grid, including the boundaries, 

 then respond with the value ("no"), and skip questions E.3-E.6. (If 

 is placed at Line E.l, Lines E.3-E.6 will not be read by GENESIS, and values 

 remaining there may be arbitrary.) 



258. Line E.3: NDG Enter the number of diffracting groins and 

 jetties NDG that are on the grid. This number includes structures that may 

 serve as boundary conditions (at grid points 1 and N+l). 



259. Line E.4: IXDG(I) Enter the grid cell numbers of diffracting 

 groins and jetties IXDG(I) in order of increasing cell number. There should 

 be the same number of grid cell locations as the number of diffracting groins 

 and jetties specified at Line E.3 (NDG values from small to large cell 

 numbers) . 



112 



