the previous (updrift) cell, only the transport rate out of the cell must be 

 adjusted in order to satisfy Equation 20. This equation contains information 

 about the upstream boundary condition. Before any adjustments are made at 

 cell face i + 1 , Equation 20 reads 



Q i + i = pp i + i Q ! + RR i + i < 26 > 



where Q? is the corrected rate made for the previous cell. This relation 

 holds unless the seawall constraint was violated. If so, then Q! . must be 

 adjusted by setting yc! equal to ys. in Equation 22, thus giving 



y Si = 2B' (Q* - Q* +1 ) + yc. (27) 



This is easily solved for the corrected transport rate for the downdrift cell: 



ys. - yc. 



Qf + i - Q? - -W^ (28) 



The procedure used to arrive at Equations 26-28 is continued in the downdrift 

 direction until either a plus cell or a boundary is encountered. 



Correction at a regular 

 cell, negative transport 



70. The procedure used here for making corrections downdrift, in the 



negative-x direction (on the other side of the minus cell), is very similar to 



the procedure described immediately above. The new transport rate at cell 



face i is given by Equation 16, i.e., 



Q! = EE! Q* „ + FF! (29) 



111+I1 v ' 



Then the corrected transport is found to be 



ys. - yc. 



This procedure is repeated downstream until a plus cell or a boundary is 

 encountered. 



30 



