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A fully worked-out version of this example can be found in the "Examples\Small directory". The files you can download include the model, and a map of the watershed at a scale of 1:24,000 (1 inch - 2000 ft.). The Argus ONE file (bluebonn.mmb) is a simple model of the Bluebonnet swamp in Baton Rouge, La. In this model it was assumed that the watershed was the recharge area for the swamp. It was also assumed that all recharge in the watershed left the watershed as stream flow out of the south end of the swamp. The baseflow discharge could thus be used to estimate the recharge rate. The topography of the aquifer was unknown so an elevation of the base of the aquifer was assumed to be 0. The aquifer was assumed to be unconfined so the top of the aquifer was set to 100 which was well above the land surface. (The top of the aquifer is not used by MODFLOW for unconfined layers.) The swamp was modeled as a set of constant head cells. The streams flowing into the swamp were modeled as drains. The conductance in the drains was set to a value large enough to prevent head from ever rising much higher than the drain elevation.
To recreate the model, you must have Argus ONE installed and also have the U.S.G.S. MODFLOW PIE in the ArgusPIE directory or a subdirectory under it. Once you have Argus ONE and the MODFLOW PIE installed, start Argus ONE. Create a new MODFLOW model (PIEs | New MODFLOW Project...). The Project Info Dialog box will open. Switch to the Geology tab and select the "Top Aquifer". Delete it by clicking on the Delete button in the dialog box. Delete "Aquitard" too. Change the name of "Bottom Aquifer" to "Aquifer". You must also change the aquifer it to an unconfined layer. Select the cell for the Aquifer under "Aquifer type" and a drop down menu will appear. Select "Convertible (1)". Change to the Packages|Stresses 1 tab and select Recharge and Drains. Close the Project Info dialog box by clicking on the OK button.
The next step is to import the map of the watershed. You will see two open windows with Argus ONE; the main window and the layers floater. The layers floater will have a list of Argus ONE layers such as "MODFLOW Domain Outline" and "MODFLOW Grid Density". You will see an open eye and a check mark in the layers floater next to "MODFLOW Domain Outline". You will need to switch to the "Maps" layer by selecting that layer in the layers floater and then clicking to the left of the eye icon. A check mark will appear next to it indicating that Maps is now the active layer. From the File Menu, select "Import Maps" and then "DXF File...". Select the file Bluebonn.dxf in the Examples\Small directory. A dialog box will appear asking you if you wish to resize the drawing to fit the map. Select OK.
The map will appear. Click somewhere off the diagram to deselect all the lines on the map. The watershed boundary and ridge lines are in red, the swamp is in blue, the topographic contours are in gray and the road system is in yellow. The swamp is located at the 15 ft. contour.
The map is at a scale of 1:24000 (1 inch = 2000 ft.); the same scale
as the U.S.G.S. topographic from which the topography was copied. We
will
set the same scale in Argus ONE. Select "Special | Rotate and Scale".
Type 200000 % in "Scale X" and under "Scale" select
"Current Layer" or "Entire Document". The visible area will expand to
be just sufficient to hold the map. so we will need to change
the visible area. We will expand the visible area slightly to create a
margin around the map. Select "Special|Scale to fit". Next we will
change the units displayed on the model from cm to feet. Select
"Special | Scale and Units" and change "Label units as" from cm
to Feet. (The
text in bold type represent choice you will need to
change.) Then select PIES|Edit
Project Info... and change the length units to feet there as
well.
You can now start using the map to create the model. First select the watershed boundary (in red) and copy it to the clipboard (Edit | Copy or Control-C). Make the Modflow Domain Outline the active layer by clicking in the check mark column in the layers floater. Paste the watershed boundary (Edit | Paste or Control-V). Double click on the line you just pasted. A dialog box will appear. Under Value, type 500. This will be the default grid size for the model.
Next we will set up a new layer for the surface topography. Make the Maps layer the active layer. (Click to the left of the eye icon.) On the Layers floater, click the "Layers..." button and a new dialog box will appear.
In the top half press the "New" button. Rename the new layer "Topography". At the bottom select "When probed for value, use Nearest Contour method". Click the Done button. Now you need to transfer the topographic data to the Topography layer. There are two ways you can do this, you can copy all the topographic contours to the topography layer and then assign them values in the same way you did with the domain outline. However, I've already done that so you can just import those contours. Make the Topograpy layer the active layer and select "File | Import Topography... | Text File" and select "Topography.exp". To see a color coded display of the values for those contours click on the down arrow in the color menu and Select Topography. (The color menu is on the left side of the main Argus ONE window.)
Next we'll add the drains to the model. We will draw a series of lines that represent the drains and we will use the topography layer to set the drain elevations. Normally, ony a single elevation is applied along the length of a line drain. However, we can change this behavior so that a drain elevation can be set using a link to another layer. First select "PIES|Edit Project Info...". Change to the "Advanced Options" tab. Select the "Use alternate Drain package export template" check box and click on the OK button. Make to the "Line Drain Unit1" the active layer and click on the "Layers..." button on the layers floater. Select "Line Drain Unit1" from the top half of the dialog box and then select "Elevation" in the lower half of the dialog box. Click on the fx button under the value column for "Elevation". This brings up the Expression editor.
Select Topography from the list. Topography will appear in the list to right of the first list. Double click on Topography in the second list. Topography will appear in the edit box at the top. Click on OK. Click on the "Done" button to continue. What you've just done is to make the default elevation the value that Argus ONE gets from the Topography layer. The topography will be evaluated at the center of each drain cell.
Now we'll create the streams. Make "Line Drain Unit1" the active layer if you have not done so already. Use the topographic contours to decide where the drains should go. You will draw a line in each of the valleys to define the drain position. To draw a line you need to select the open contour button. One of the buttons on the left will show a little box with "Contour" if you hold the cursor over it briefly. (This is a "tool tip".) Click on that button and hold the mouse button down until a pop up menu appears. Select the middle item which is the "Open Contour" tool. (The other two are the "Closed Contour" tool and the "Point" tool.) Now start drawing lines where the stream should go. When you are finished with each stream, a dialog box will appear. For the time being don't fill these in, just select OK. We will assign all the contours the same value at one time when we get done drawing contours. You will probably want to allow the drains to intersect one another so either select Special | Allow Intersection or find the button with the tool tip "Allow Intersection" and click on it. If you need to edit the position of one of the lines, click on the line to select it and then click on the node you want to edit. The square at the node will change from black to white to show that just that node is selected. You can then drag that node to a new position. Remember that the swamp is at the 15 ft. contour so you the drains should start or end there.
When you have finished drawing all the drains, you need to set their properties. We will use the default elevation for all the drains. However, we will set the other properties in a different way. Select all the drains. There are several ways to do this. The easiest may be to select "Edit | Select All". Other ways would be to use the arrow tool to draw a box around all the contours or to use the lasso tool to draw a curved line. The latter two methods are useful when you only want to select some of the objects on a layer. Once you have selected all the objects, click on the Arrow button if it is not already selected, and double-click on any of the objects. A dialog box will appear. It will look much like those you saw before when drawing the drain contours but now there are a few extra buttons.
Enter a value of 5e-7 for the Conductance Multiplier and a value of
1 for On or
Off Stress1. (Argus ONE uses 0 for False and any other value for True.
Setting
a value of 1 will mean that the drain will be active. If you had
several
stress periods, the drain could be active during some stress periods
and
inactive during others.) We don't want to set any of the other
parameters here so click on the check marks on the far left next to
the other parameters. Now click on the Set All button and then on the
OK button. Note that the backgrounds for values you specified in
the Contour Information dialog box are gray but that the others are
white. A gray background means that the value has been specified
for the contour rather than coming from an Expression for the
layer. Values specified in the Contour Information dialog box
override Expressions.
The next thing to do is to make the swamp a constant head zone. Go back to Maps and select the swamp (in blue) and copy it to the clipboard. Paste it on the Prescribed Head Unit1 layer. Double click on it and assign it a value of 15 which is the head in the swamp.
We're almost done entering data for the model. The only thing we need to do is to set the default values for some parameters. We will have uniform values throughout the model so that is all we need to do with those properties. However, we could have any of these parameters vary spatially if we wanted to.
Press the "Layers..." button on the Layers floater again and select "Recharge" from the top half of the dialog box. Select Stress1 from the lower half of the dialog box and click on fx button under "Value" to bring up the expression editor. This time instead of selecting a layer from the list, just type a value of 1e-10. You do not need to set the Elevation parameter. (It is only used if we set the Recharge Option in the Edit Project Info dialog box to "Vert distribution in IRCH (2)".
In the same way set the following default values.
Layer | Default Value |
---|---|
Recharge.Stress1 |
1e-10 |
Elevation Top Unit1 | 100 |
Elevation Bottom Unit1 | 0 |
Hydraulic Cond Unit1.Kx | 0.0000015 |
Hydraulic Cond Unit1.Kz | 0.0000015 |
Initial Head Unit1 | 15 |
You've now finished entering data for the model. All you need to do is make the grid and run the model. This is very easy. Go to the MODFLOW FD Grid Layer. One of the buttons has the tool tip "Magic Wand". Select it and click anywhere within the domain outline. The Grid Angle dialog box will appear. Make sure the "Automatic Angle Calculation" check box is checked. (It should be checked by default.) Click on the OK button. Argus ONE will create the grid.
Now we can run the model. However, lets change the name of the output file so we will recognize it when we are done. Select "PIEs | Edit Project Info". Click on the "Output Files" tab and change the root name for MODFLOW Simulation files to "bluebonn". You must use a word with 8 characters or less. Click on the OK button.
To run the model select "PIE | Run MODFLOW/Solute Transport" and click on the OK button. A dialog box will appear. Use it to select the directory in which the MODFLOW input and output files will be saved. Argus ONE will export the model and then a DOS box will open as MODFLOW runs. The DOS box will prompt you to "Press any key to continue" when the model is finished running.
Of course, there isn't much point in running the model if you can't see the results. We'll look at the results in the form of a contour map. Select "PIEs | MODFLOW/Solute-Transport Post-Processing...". Click the "Select Data Set" button and then select the file bluebonn.fhd. Click on the OK button. Select "Contour Map" and click on the OK button. A contour map will appear.
You may wish to add a little text to the Contour map to identify it.
Go to the "MODFLOW Post Processing Charts1" layer and click on
the "Text" button. Drag with the mouse to create a rectangle where
you wish the text to appear. When you release the mouse, a dialog box
will
appear. Type the text and click on the OK button. You can resize the
text
later by dragging the corners of the text box or double clicking on the
text and changing "Size". You can also set the font of the
text. In this example, the font is Times New Roman and "bold" is
selected.