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A Data Input Program (MFI) for the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow Model
U.S. Geological Survey Water-Resources Investigations Report 94-468

Parameters that MFI Calculates


Those already familiar with MODFLOW or those who carefully examine the MODFLOW and MODPATH input instructions will notice that the MFI data screens do not directly include all parameters required for MODFLOW and MODPATH. This is because MFI calculates some parameters either by assumption or from other requested information. Table 2 lists the parameters that are calculated by some method other than direct data entry.

Table 2. Parameters that MFI calculates (PostScript file of Table 2)

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 Option  Parameter                     How Calculated                                                               
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BAS      IAPART   0 if LAYAVG (Goode and Appel, 1992) is not 30; 1 if
                  LAYAVG is 30.

BAS      ISTRT    0 when drawdown is not calculated; 1 when drawdown is
                  calculated.

BAS      IUNIT    Unit numbers for files are automatically selected.

BAS      NPER     User specified when transient; 1 when steady state.

BAS      PERLEN   User specified when transient; 1.0 when steady state.

BAS      NSTP     User specified when transient; 1 when steady state.

BAS      TSMULT   User specified when transient; 1.0 when steady state.

BAS      ITMUNI   User specified when transient; set to "UNDEFINED" when
                  steady state.

BCF      ISS      Determined from the "Steady State/Transient" option
		  specified in the Miscellaneous input screen for the
		  Basic Package; 0 if transient, and 1 if steady
		  state.

BCF      IBCFCB   Determined from data entered in Output Control
                  screens.

RIV      ITMP     Determined by counting the reaches entered by the
                  user.

RIV      MXRIVR   Determined by looking at the number of reaches used
		  in each stress period and finding the maximum number.

RIV      IRIVCB   Determined from data entered in Output Control
                  screens.

WEL      ITMP     Determined by counting the wells entered by the user.

WEL      MXWELL   Determined by looking at the number of wells used in
		  each stress period and finding the maximum number.

WEL      IWELCB   Determined from data entered in Output Control
                  screens.

DRN      ITMP     Determined by counting the drains entered by the user.

DRN      MXDRN    Determined by looking at the number of drains used in
		  each stress period and finding the maximum number.

DRN      IDRNCB   Determined from data entered in Output Control
		  screens.

GHB      ITMP     Determined by counting the boundaries entered by the
		  user.

GHB      MXBND    Determined by looking at the number of boundaries used
		  in each stress period and finding the maximum number.

GHB      IGHBCB   Determined from data entered in Output Control
                  screens.

RCH      INRECH   -1 if RECH array is reused from previous stress period;
                  otherwise 0.

RCH      INIRCH   -1 if IRCH array is reused from previous stress period;
                  otherwise 0.

RCH      IRCHCB   Determined from data entered in Output Control screens.

EVT      INIEVT   -1 if IEVT array is reused from previous stress period;
                  otherwise 0.

EVT      INEVTR   -1 if EVTR array is reused from previous stress period;
                  otherwise 0.

EVT      INEXDP   -1 if EXDP array is reused from previous stress period;
                  otherwise 0.

EVT      INSURF   -1 if SURF array is reused from previous stress period;
                  otherwise 0.

EVT      IEVTCB   Determined from data entered in Output Control screens.

SIP      NPARM    Always 5.

SIP      IPCALC   0 if WSEED is not 0; 1 if WSEED is 0.

PCG      NPCOND   Always 1.

PCG      NBPOL    Always 2.

PCG      IPCGCD   Always 0.

Output   IHEDUN   0 if head is not saved.  If head is saved, unit number
		  is automatically selected.

Output   IDDNUN   0 if drawdown is not saved.  If drawdown is saved, unit
		  number is automatically selected.

Output   INCODE   Determined from data entered in Output Control screens.

Output   IHDDFL   Determined from data entered in Output Control screens.

Output   IBUDFL   Determined from data entered in Output Control screens.

Output   ICBCFL   Determined from data entered in Output Control screens.

Output   Hdpr     Determined from data entered in Output Control screens.

Output   Ddpr     Determined from data entered in Output Control screens.

Output   Hdsv     Determined from data entered in Output Control screens.

Output   Ddsv     Determined from data entered in Output Control screens.

Modpath  IGRID    Always 0.

Modpath  NCBL     Calculated by counting the number of layers for which
		  NCON (the confining bed code) is not 0.

Modpath  TOP      For layers below the top layer, TOP is defined as the
		  BOT of the layer above when there is no confining layer
		  above; otherwise TOP is either user defined or the
		  elevation of the water table.
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