GWT-DISV

Structure of Blocks

FOR EACH SIMULATION

    BEGIN OPTIONS
      [LENGTH_UNITS <length_units>]
      [NOGRB]
      [GRB6 FILEOUT <grb6_filename>]
      [XORIGIN <xorigin>]
      [YORIGIN <yorigin>]
      [ANGROT <angrot>]
      [EXPORT_ARRAY_ASCII]
      [EXPORT_ARRAY_NETCDF]
      [CRS <crs>]
      [NCF6 FILEIN  <ncf6_filename>]
    END OPTIONS

    BEGIN DIMENSIONS
      NLAY <nlay>
      NCPL <ncpl>
      NVERT <nvert>
    END DIMENSIONS

    BEGIN GRIDDATA
      TOP [NETCDF]
            <top(ncpl)> -- READARRAY
      BOTM [LAYERED] [NETCDF]
            <botm(ncpl, nlay)> -- READARRAY
      [IDOMAIN [LAYERED] [NETCDF]
            <idomain(ncpl, nlay)> -- READARRAY]
    END GRIDDATA

    BEGIN VERTICES
      <iv> <xv> <yv>
      <iv> <xv> <yv>
      ...
    END VERTICES

    BEGIN CELL2D
      <icell2d> <xc> <yc> <ncvert> <icvert>
      <icell2d> <xc> <yc> <ncvert> <icvert>
      ...
    END CELL2D

Explanation of Variables

Block: OPTIONS

  • length_units is the length units used for this model. Values can be “FEET”, “METERS”, or “CENTIMETERS”. If not specified, the default is “UNKNOWN”.

  • NOGRB keyword to deactivate writing of the binary grid file.

  • GRB6 keyword to specify that record corresponds to a binary grid file.

  • FILEOUT keyword to specify that an output filename is expected next.

  • grb6_filename defines a binary grid output file. If this option is not provided, the output file will have the same name as the discretization input file, plus extension “.grb”.

  • xorigin x-position of the origin used for model grid vertices. This value should be provided in a real-world coordinate system. A default value of zero is assigned if not specified. The value for XORIGIN does not affect the model simulation, but it is written to the binary grid file so that postprocessors can locate the grid in space.

  • yorigin y-position of the origin used for model grid vertices. This value should be provided in a real-world coordinate system. If not specified, then a default value equal to zero is used. The value for YORIGIN does not affect the model simulation, but it is written to the binary grid file so that postprocessors can locate the grid in space.

  • angrot counter-clockwise rotation angle (in degrees) of the model grid coordinate system relative to a real-world coordinate system. If not specified, then a default value of 0.0 is assigned. The value for ANGROT does not affect the model simulation, but it is written to the binary grid file so that postprocessors can locate the grid in space.

  • EXPORT_ARRAY_ASCII keyword that specifies input griddata arrays should be written to layered ascii output files.

  • EXPORT_ARRAY_NETCDF keyword that specifies input gridded arrays should be written to the model output NetCDF file with attributes that support using the generated file as a MODFLOW 6 simulation input. This option only has an effect when an output model NetCDF file is configured and the simulation is run in VALIDATE mode, otherwise it is ignored.

  • crs is a real-world coordinate reference system (CRS) for the model, for example, an EPSG integer code (e.g. 26915), authority string (i.e. epsg:26915), or Open Geospatial Consortium Well-Known Text (WKT) specification. Limited to 5000 characters. The entry for CRS does not affect the model simulation, but it is written to the binary grid file so that postprocessors can locate the grid in space.

  • NCF6 keyword to specify that record corresponds to a NetCDF configuration (NCF) file.

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

  • ncf6_filename defines a NetCDF configuration (NCF) input file.

Block: DIMENSIONS

  • nlay is the number of layers in the model grid.

  • ncpl is the number of cells per layer. This is a constant value for the grid and it applies to all layers.

  • nvert is the total number of (x, y) vertex pairs used to characterize the horizontal configuration of the model grid.

Block: GRIDDATA

  • top is the top elevation for each cell in the top model layer.

  • botm is the bottom elevation for each cell.

  • idomain is an optional array that characterizes the existence status of a cell. If the IDOMAIN array is not specified, then all model cells exist within the solution. If the IDOMAIN value for a cell is 0, the cell does not exist in the simulation. Input and output values will be read and written for the cell, but internal to the program, the cell is excluded from the solution. If the IDOMAIN value for a cell is 1, the cell exists in the simulation. If the IDOMAIN value for a cell is -1, the cell does not exist in the simulation. Furthermore, the first existing cell above will be connected to the first existing cell below. This type of cell is referred to as a “vertical pass through” cell.

Block: VERTICES

  • iv is the vertex number. Records in the VERTICES block must be listed in consecutive order from 1 to NVERT.

  • xv is the x-coordinate for the vertex.

  • yv is the y-coordinate for the vertex.

Block: CELL2D

  • icell2d is the CELL2D number. Records in the CELL2D block must be listed in consecutive order from the first to the last.

  • xc is the x-coordinate for the cell center.

  • yc is the y-coordinate for the cell center.

  • ncvert is the number of vertices required to define the cell. There may be a different number of vertices for each cell.

  • icvert is an array of integer values containing vertex numbers (in the VERTICES block) used to define the cell. Vertices must be listed in clockwise order. Cells that are connected must share vertices.