Back to MODFLOW Tutorial Table of Contents.
We're going to start with a very simple example. You will edit an existing model that is in the "Examples\Simple" directory beneath the directory in which you installed this tutorial. Everything in the model has already been done for you. You can just modify it in various ways to see how the results are changed.
This model has a single confined aquifer, a well and a river.
This model has already been run so it already has data displayed. However, let's run the model again. Show the layers floater, if it is not visible by selecting View|Show Layers Window. Next, change to the MODFLOW FD Grid layer if that is not already the active layer. To make it active, click on the far left size of the Layers floater next to MODFLOW FD Grid layer. A check mark will appear next to MODFLOW FD Grid layer and it will become the active layer. From the "PIEs" menu select "Run MODFLOW/Solute Transport...". A dialog box will appear. Look in the status bar and make sure that the path for MODFLOW-2000 is correct. The status bar will be empty if the path is correct. The status bar will be red and display an error message if the path is incorrect. If the path is incorrect, change it on the Model Paths tab. Otherwise, change nothing and select "OK". You will be prompted to enter the export file name. Accept the default name. Argus ONE will create the input files for MODFLOW and then try to start MODFLOW. If you have MODFLOW-2000 installed in the correct location, a DOS window will open and MODFLOW will start running. You can only export the MODFLOW input files and run MODFLOW from the MODFLOW FD Grid layer.
When the MODFLOW finishes, "Press any key to continue..." will appear in the DOS window. Press a key. Under Windows NT, Windows 2000 or Windows XP, the DOS window will close. Under Windows 95, you will need to close the DOS window. Now we can look at the results. Select "PIEs|MODFLOW/MOC3D Post Processing". Select "MODFLOW (Formatted Head and Drawdown)". Then click on the Select Data Set button and select the file "simple.fhd". This contains the calculated heads. ("Simple.fdn" contains the calculated drawdowns.) A new dialog box will appear. You will only have one choice as displayed below. Select "Head Per 1 TS 1 Time 1" This is the head in layer 1 for stress period 1 time step 1 at an elapsed time of 1. (This particular model only has one layer, one stress period and one time step but a model can have many more or each. It can have up to 999 layers and an unlimited number of stress periods and time steps.) If it is not already selected, select "Contour Map" from the list of chart types. Click on the OK button. A new contour map will appear.
The two contour maps are not quite the same because I adjusted the contour interval of the map already in simple.mmb. Because the two contour maps are both displayed simultaneously, you will probably want to hide one of them. On the layers floater, click on the "eye" icon next to "MODFLOW Contour Map" to hide it.
You might want to look at the results in 3D. Do what you did before to import heads but this time select 3D surface from the list of chart types. This time, you will be prompted to either overwrite the existing data layer and post processing chart layer. In this case you can overwrite the data in the data layer because it is exactly the same data as before. However, you should create a new postprocessing chart. You will probably want to hide the grid and other layers at this point. You can do that from the Layers Floater. If the Layers Floater isn't visible, select "View|Show Layers Window". The very last Window should be "MODFLOW Post Processing Charts2". Click on the far left next to it. A check mark should appear next to the open eye icon. This means that "MODFLOW Post Processing Charts2" is the active chart and is ready to be edited by you. Now click the "None" button on the top of the Layers Floater. This hides all layers except the active layer.
In this case, the 3D diagrams will look better if we increase the vertical relief. To do that, just double click on the diagram. A dialog box will open. Uncheck the "Calculate automatically" check box and change "Scale Factor" to 0.4. Click OK to close the dialog box.
Now would be a good point to just play with the model and see how changing the model will change the results. It's possible, that some changes might make it impossible to run the model. For example, if you made the top of the aquifer lower than the bottom of the aquifer, MODFLOW might not run. If that happens, don't worry about it too much at this point.
Before doing anything else, use the layers window to display the "MODFLOW FD Grid", "Wells, Unit1", and "Line River Unit1" layers. You can make them visible by clicking on the closed eye icon in the floater window next to the name of the layer. Make "Wells, Unit1" the active layer by clicking to the left of the eye icon for "Wells, Unit1". Finally hide the MODFLOW Post Processing Charts layer by clicking on the open eye icon to the left of it in the Layers Floater to change it to a closed eye icon.
Here are some things you can do.
Use the layers floater to make "Wells, Unit1" the active layer if you have not already done so. Click on the square that represents the well and keep the mouse button held down. Move the mouse with the mouse button held down. That will drag the well to a new position. Release the mouse button when you have reached the position you want. Now run MODFLOW and see how the results have changed. You will need to reimport the revised data as described under "Displaying Results from MODFLOW".
Use the layers floater to make "Wells Unit1" the active layer if you have not already done so. Double click on the square that represents the well. A dialog box will appear. Change Stress1 to the desired pumping rate (in m3/s). Positive numbers for Stress1 represent injection wells. Negative numbers represent pumping wells. Click on OK and run MODFLOW and see how the results have changed. You will need to reimport the revised data as described under "Displaying Results from MODFLOW".
Use the layers floater to make "MODFLOW Domain Outline" the active layer. It is the very first layer. You will see a dark rectangle appear around the outside of the grid. It will be labeled "Domain Outline". Double click on it. When the dialog box opens, change the value of MODFLOW Grid Cell Sie (6000) to some other value, for example, 8000. The density is the desired size of the grid cells. Now change the active layer to the "MODFLOW FD Grid" layer. You'll see a button on the left called the Magic Wand. If you don't recognize it, just hold the mouse over each button briefly and a brief description of that button will appear. Click on the Magic Wand button and then click on the grid. A dialog box will appear that tells you there is already a grid present. Click on the regrid button. After a brief wait, a new grid will appear. If you run the model now, the model should run faster. (It will also be a bit less accurate.) To see the results, you will need to reimport the revised data as described under "Displaying Results from MODFLOW".
Use the layers floater to make "Wells Unit1" the active layer if you have not already done so. Click on the square that represents the well. The well should turn black (if it wasn't black already. Press the "Delete" key on the keyboard to delete the well. Now run MODFLOW and see how the results have changed. You will need to reimport the revised data as described under "Displaying Results from MODFLOW".
Use the layers floater to make "Recharge" the active layer.
Click on the contour button and hold the mouse button down until a
pop-up
menu appears.
Select the top choice from the pop-up menu. Now click in the model.
Move
the mouse and click again. There will be a line connecting the two
points
where you clicked. Keep on clicking to outline an area where you want
to
set the recharge rate. Double click and then move the mouse slightly
when
you are finished. A dialog box will appear. Change Stress1 to a
different
value. Run MODFLOW and see how the results have changed. To see the
results, you will need to reimport the revised data as described under "Displaying Results from MODFLOW".
Use the same procedure you used to change the recharge rate to change the top or bottom of one or more layers. To see the results, you will need to reimport the revised data as described under "Displaying Results from MODFLOW".