^ 2 

 - f H 







IMAX-l 



dx 



1 



i=l 



(60) 



where IMAX corresponds to the number of water cells within the surf zone. 

 Equation 60 allows for a gradual variation in cell size Ax . The velocity 

 v„ is taken as the magnitude of the resultant of the total velocity 



components u and v in the x- and y-directions. 



/ 2 . 2 

 v^ = ^u^ + v^ 



Thus 



(61) 



where 



u^ = u + U 



(62) 



v„ = v + V 

 T 



(63) 



For each computational grid line from the shoreline to the breaker line for 

 each time-step, the value of I„ is used to determine the unknown coefficient 

 k^ from Equations 56 and 59: 



KH, c sin a, cos a. 



^^1 = 



■nf I, 



(64) 



The value of K is taken to be 0.39 if significant wave heights are used as 

 in this study ( Shore Protection Manual (SPM) 1984) . 



64. Once k is known, the local transport rate i may be determined 

 from Equation 57 and hence the local volumetric sediment transport rate q , 

 as in the following equation: 



irk^fpY hv^ 

 i (Pg - P) a' 



(65) 



where 



p = mass density of solids 

 s 



- 2.65 p for sand 

 a' = ratio of volume of solids to total volume of sediment 

 =0.6 for sand 



38 



