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      SUBROUTINE UPDATE_CBCM
CNG2014 This version if for barotropic only with Manning's n.
      INCLUDE 'comdeck'
      SAVE

      Do 6030 J = 1, JM
        Do 6020 I = 1, IM
          If (FSM(I,J).NE.0.0) Then
              CBCMIN = BFRIC
              CBC(I,J)=AMAX1(CBCMIN,GRAV*VARMN(I,J)*VARMN(I,J)/
     +                  (AMAX1(DT(I,J),WETMIN)**(1./3.)))
          Else
           CBC(I,J)=BFRIC !Initialize CBC even at FSM=0 cells
          END IF
          CBC(I,J) = AMIN1(CBC(I,J),1.) ! DO NOT ALLOW CBC TO EXCEED UNITY.
 6020   CONTINUE
 6030 CONTINUE

      RETURN
      END