Simple Model: Aquifer Properties

The only aquifer properties that need to be specified are the horizontal and vertical hydraulic conductivities as shown in the table below. The horizontal hydraulic conductivity only needs to be simulated for the simulated layers. The vertical hydraulic conductivity needs to specified in both the simulated and nonsimulated layers.

To illustrate different methods of assigning properties, objects will be used to assign Kx whereas a formula will be used to assign Kz. First confirm that the selected layer is the top layer. One way to do that is to move the cursor over the red Selection cube on the top view of the model. The selected layer will be displayed on the Status bar. Next select Object|Create|Rectangle and click twice on the top view of the model to create a rectangle that completely encloses the grid. The Object Properties dialog box will appear. Change the name of the object to "Upper_Aquifer_Kx." Examine the formulas for the Higher Z coordinate and Lower Z coordinate and verify that they are "Model_Top" and "Upper_Aquifer_Bottom." Select the Data Sets tab, expand "Required|Hydrology" and check the check box next to "Kx." Change the formula for the Kx data set to "0.001" and click the OK button.

Next change the selected layer to layer 3 (the middle aquifer). One way to do that is to click twice beneath the red square on the Selection cube on the top view of the model to move the selected layer down. You will need to click twice to move the selected layer down two layers from layer 1 to layer 3. Create another rectangle object that completely surrounds the grid. In the Object Properties dialog box, change the name of the object to "Middle_Aquifer_Kx." Examine the formulas for the Higher Z coordinate and Lower Z coordinate and verify that they are "Upper_Confining_Bed_Bottom" and "Middle_Aquifer_Bottom." These formulas mean that the top of the object is at the top of layer 3 and the bottom of the object is at the bottom of layer 3. On the Data Sets tab, check the check box for the Kx data set and leave the formula for the Kx data set to "0.0001" and click the OK button. Repeat this process again to assign Kx a value of 0.0002 in layer 5. (Be sure to change the selected layer to the bottom layer before creating the object used to specify Kx for the bottom layer.)

To define different values of Kz for each layer, select Data|Edit Data Sets... Expand "Required|Hydrology" and select Kz. The default formula for the Kz data set is "Kx / 10." Click the Edit formula button to display the Formula Editor. Expand "Functions|Logical" and double click on CaseR.The formula will change to "CaseR(Index, Real_Result1, Real_Result2, ...)." In the formula, double-click on "Index" to select it. In the list of formulas, close "Logical" and expand "Grid." Then double click on "Layer." The formula should now be "CaseR(Layer, Real_Result1, Real_Result2, ...)." Type in the values of Kz for each layer so that the formula becomes "CaseR(Layer, 1., 1e-6, 1., 5e-7, 1.)." This formula will assign a different value to Kz for each layer. Kz in layers 1, 3, and 5 will be assigned a value of 1; Kz in layer 2 will be assigned a value of 1e-6; and Kz in layer 4 will be assigned a value of 5e-7. Click OK to close the Formula Editor. Then click Apply to make the change in the Data Sets dialog box and then click Close..