CSUB Example: CSUB Package Interbed Properties

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The following properties are defined for individual interbeds. Except for the Interbed Thickness, all the properties are the same in all the layers. We will use objects to define these properties.

 

Interbed System

Initial Stress Offset (pcs0)

Interbed Thickness (thick_frac)

Equivalent Interbed Number (rnb)

Initial Inelastic Compression Index (ssv_cc)

Initial Elastic Recompression Index (sse_cr)

Initial Porosity (theta)

Delay Kv (kv)

Initial Delay Head Offset (h0)

Layer 1

Upper Aquifer

15

45

1 (not used)

0.25

0.01

0.45054945

2.5E-6 (not used)

0 (not used)

Layer 2

Upper Aquifer

15

70

1 (not used)

0.25

0.01

0.45054945

2.5E-6 (not used)

0 (not used)

Layer 3

Confining Bed

15

50

1 (not used)

0.25

0.01

0.45054945

2.5E-6 (not used)

0 (not used)

Layer 4

Lower Aquifer

15

90

1 (not used)

0.25

0.01

0.45054945

2.5E-6 (not used)

0 (not used)

Use the Selection Cube to make layer 1 the selected layer. Then create a polygon or rectangle object covering all the active cells in the top view of the model except the ones in the last row where the specified head boundaries are located.

CSUB Example: Specifying CSUB cells

In the Object Properties dialog box, make sure the Z-formulas are specified so that the top two layers are included.

CSUB Example: CSUB cell Z-Formulas

Go to MODFLOW Features and check the checkbox for the CSUB package. Then, on the Interbed systems tab of the CSUB pane, check the Used checkbox for the Upper Aquifer Interbed system. Then enter the values for the top two layers. For Interbed Thickness, an appropriate formula would be "If((Layer = 1.), 45, 70)." You don't need to specify anything on the Transient tab. Click OK to close the Object Properties dialog box.

CSUB Example: Interbed properties

To assign values for the other interbeds in layers 3 and 4, use the Selection Cube to make the appropriate layers active and then create objects covering the same cells on the top view of the model as before. For each object, assign the Interbed properties in the same way as before except use values appropriate to the selected layer.