The Rock/Soil Zonation Card is used to associate rock/soil types with grid cells. There are three basic options for declaring the distribution of rock/soil types:
The explicit zonation option is best suited for simulations with a limited number of rock/soil types. The approach is to define rock/soil names and then associate those names with a spatial zone across the computational domain. Rock/soil names are generally unrestricted, but need to be less than 64 characters in length. Intrinsic properties of the defined rock/soil types will then be associated with the grid cells within the spatial zone on other input cards (e.g., Hydraulic Properties Card, Mechanical Properties Card, Saturation Function Card, Aqueous Relative Permeability Card). Spatial zones are specified using ranges of indices in the three local grid directions.
The external file option is similar to the explicit zonation option, but the association of define rock/soil types with grid cells is via the external file. The external files contain one integer for every grid cell, using conventional i, j, k ordering. The integer corresponds with one of the defined rock/soil types. A value of 0 is used to indicate that the grid cell is inactive.
This option should be used when every grid cell is associated with a unique rock/soil type, as common with statistically generated rock/soil distributions. With IJK Indexing the concept of rock/soil types is abandoned for a system where the intrinsic properties of the geologic media are associated with the grid cell.
If IJK Indexing is specified in the Rock/Soil Zonation Card then the following cards must also have the Rock/Soil Name identified as "IJK Indexing:"
Mechanical Properties Card, Hydraulic Properties Card, Saturation Function Card, Aqueous Relative Permeability Card, Directional Aqueous Relative Permeability Card