GWT-CNC

Structure of Blocks

FOR EACH SIMULATION

    BEGIN OPTIONS
      [AUXILIARY <auxiliary(naux)>]
      [AUXMULTNAME <auxmultname>]
      [BOUNDNAMES]
      [PRINT_INPUT]
      [PRINT_FLOWS]
      [SAVE_FLOWS]
      [TS6 FILEIN <ts6_filename>]
      [OBS6 FILEIN <obs6_filename>]
    END OPTIONS

    BEGIN DIMENSIONS
      MAXBOUND <maxbound>
    END DIMENSIONS

FOR ANY STRESS PERIOD

    BEGIN PERIOD <iper>
      <cellid(ncelldim)> <conc> [<aux(naux)>] [<boundname>]
      <cellid(ncelldim)> <conc> [<aux(naux)>] [<boundname>]
      ...
    END PERIOD

Explanation of Variables

Block: OPTIONS

• auxiliary defines an array of one or more auxiliary variable names. There is no limit on the number of auxiliary variables that can be provided on this line; however, lists of information provided in subsequent blocks must have a column of data for each auxiliary variable name defined here. The number of auxiliary variables detected on this line determines the value for naux. Comments cannot be provided anywhere on this line as they will be interpreted as auxiliary variable names. Auxiliary variables may not be used by the package, but they will be available for use by other parts of the program. The program will terminate with an error if auxiliary variables are specified on more than one line in the options block.

• auxmultname name of auxiliary variable to be used as multiplier of concentration value.

• BOUNDNAMES keyword to indicate that boundary names may be provided with the list of constant concentration cells.

• PRINT_INPUT keyword to indicate that the list of constant concentration information will be written to the listing file immediately after it is read.

• PRINT_FLOWS keyword to indicate that the list of constant concentration flow rates will be printed to the listing file for every stress period time step in which “BUDGET PRINT” is specified in Output Control. If there is no Output Control option and “PRINT_FLOWS” is specified, then flow rates are printed for the last time step of each stress period.

• SAVE_FLOWS keyword to indicate that constant concentration flow terms will be written to the file specified with “BUDGET FILEOUT” in Output Control.

• TS6 keyword to specify that record corresponds to a time-series file.

• FILEIN keyword to specify that an input filename is expected next.

• ts6_filename defines a time-series file defining time series that can be used to assign time-varying values. See the “Time-Variable Input” section for instructions on using the time-series capability.

• OBS6 keyword to specify that record corresponds to an observations file.

• obs6_filename name of input file to define observations for the Constant Concentration package. See the “Observation utility” section for instructions for preparing observation input files. Tables ref{table:gwf-obstypetable} and ref{table:gwt-obstypetable} lists observation type(s) supported by the Constant Concentration package.

Block: DIMENSIONS

• maxbound integer value specifying the maximum number of constant concentrations cells that will be specified for use during any stress period.

Block: PERIOD

• iper integer value specifying the starting stress period number for which the data specified in the PERIOD block apply. IPER must be less than or equal to NPER in the TDIS Package and greater than zero. The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block. The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block.

• cellid is the cell identifier, and depends on the type of grid that is used for the simulation. For a structured grid that uses the DIS input file, CELLID is the layer, row, and column. For a grid that uses the DISV input file, CELLID is the layer and CELL2D number. If the model uses the unstructured discretization (DISU) input file, CELLID is the node number for the cell.

• conc is the constant concentration value. If the Options block includes a TIMESERIESFILE entry (see the “Time-Variable Input” section), values can be obtained from a time series by entering the time-series name in place of a numeric value.

• aux represents the values of the auxiliary variables for each constant concentration. The values of auxiliary variables must be present for each constant concentration. The values must be specified in the order of the auxiliary variables specified in the OPTIONS block. If the package supports time series and the Options block includes a TIMESERIESFILE entry (see the “Time-Variable Input” section), values can be obtained from a time series by entering the time-series name in place of a numeric value.

• boundname name of the constant concentration cell. BOUNDNAME is an ASCII character variable that can contain as many as 40 characters. If BOUNDNAME contains spaces in it, then the entire name must be enclosed within single quotes.

Example Input File

    BEGIN OPTIONS
      PRINT_FLOWS
      PRINT_INPUT
      SAVE_FLOWS
    END OPTIONS
    
    BEGIN DIMENSIONS
      MAXBOUND  1
    END DIMENSIONS
    
    BEGIN PERIOD 1
      1 1 1 1.0
    END PERIOD

Available Observation Types

Stress Package	Observation Type	ID1	ID2	Description
CNC	cnc	cellid or boundname	--	Mass flow between the groundwater system and a constant-concentration boundary or a group of cells with constant-concentration boundaries.

Example Observation Input File

    BEGIN OPTIONS
      DIGITS 8
      PRINT_INPUT
    END OPTIONS
    
    BEGIN CONTINUOUS FILEOUT my_model.cnc01.csv
    # obsname  obstype   ID
      cnc_2_1  CNC       1 1 2
      cnc_2_2  CNC       1 2 2
      cnc_2_3  CNC       1 3 2
      cnc_2_4  CNC       1 4 2
    END CONTINUOUS
    
    BEGIN CONTINUOUS FILEOUT my_model.chd02.csv
    # obsname     obstype   ID
      cnc_3_flow  CNC       CNC_1_3
    END CONTINUOUS