GMS

Running MODFLOW Outside of GMS

By aquaveo on April 20, 2022

Do you have a MODFLOW project you created in GMS, but realize you need to run MODFLOW outside of GMS? This is sometimes necessary if you have a very specific need for your project that can only be accomplished by modifying the exported files before running the MODFLOW simulation. This does not happen often, but when you do encounter a situation where you need to run MODFLOW outside of GMS, do the following:

  1. Open the MODFLOW Global Options and make certain that the Save as Native Text option has been turned on. This is necessary to generate files for your project that you can edit. With the native text option turned on, saving your project will generate the native text files.
  2. One you have the native text files generated, you can then edit the files manually using a text editor. GMS will create a separate directory with the native MODFLOW files. This directory will typically be the project name with "_text" appended to it. For example, if the project is named "Aquifer", the directory will be named "Aquifer_text". Keep these files together.
    3. Running MODFLOW using the Command Prompt
  3. To run the native files, use either a command line with a DOS prompt or a batch file. See guidance for how to do this on USGS's website.
  4. After you have successfully run your MODFLOW simulation, import back into GMS to visualize the results and perform additional analyses using the tools in GMS. You will need to start by importing either the NAM file or MFN file. These files contain a directory for the other files in the MODFLOW project and how they should be opened. It is important to keep all of the MODFLOW files together in the same directory. Having only the NAME or MFN file will not be enough to open the MODFLOW project. Files for the packages used with the project will typically have a file extension that matches the package. For example, the Wells package will have the extension "*.wel".

Running the native files outside of GMS can be used to validate results of a GMS model or to add custom parameters not available in GMS. However, Aquaveo may not be able to provide technical support for simulations that have been extensively modified outside of the GMS application.

Knowing how to run MODFLOW outside of GMS can give you more options for modeling with GMS. Try out GMS 10.6 today!

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Registering an Image in XMS

By aquaveo on April 13, 2022

Do you have an image that you would like to add to your project, but that image doesn’t have any coordinate information? Many projects require that you have an image or map that defines the proposed location for structures, wells, or other objects. In XMS (GMS, SMS, and WMS) the image needs to have coordinate information in order to correctly align with the project data. If your image does not have coordinate information, the Register Image dialog will appear.

Example of the Register Image dialog

To use the Register Image dialog, designate three points on the image and enter the coordinate information for those points. XMS will then use those coordinates to create the coordinate data for the entire image. It is possible to register an image using only two points, but three points is recommended.

If you do not know the coordinate information for any points on the image, here is a tip for getting coordinate information for the image.

  1. Click the Add Online Maps macro to open the Virtual Earth Map Locator dialog.
  2. Search for the area of your image by putting the name into the search bar and click Jump to Search Location.
  3. Be sure that the entire project bounds are within the window and match the area of your unregistered image.
  4. Download the new image and set the projection for this image.
    5. Note: you could just use this new image, but if the image you are trying to import shows the location of proposed structures, boreholes, etc., then you may need to still import the unregistered image.
  5. Outside of XMS, use a photo viewer to open the unregistered image.
  6. Compare both images and find three places where you can easily tell that the images match up.
  7. Now, in XMS, place your mouse over one of the three locations that you will need the geographical coordinates for.
  8. At the bottom of XMS you can view the coordinate information. Write down the coordinate information, then repeat in two other places.
  9. Now that you have all of the location coordinates you need to register the image, open the unregistered image file in XMS to bring up the Register Image dialog.
  10. Click the three points you have coordinate information for and enter in the coordinates that you wrote down earlier.
  11. After registering the image, check the alignment of the images if needed.

    12. Try registering an image for your project in SMS, GMS, or WMS today!

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Exporting Using the View Values Command

By aquaveo on March 30, 2022

In your groundwater model in GMS, do you need to export only a specific dataset value? GMS provides a way for you to export different dataset values and save them as text files that you can continue to edit outside of GMS. This post will cover exporting values using the View Values command.

To export data using the View Values command, select a dataset in the Project Explorer then right-click and select the View Values command. This will open the Edit Dataset Values dialog. This dialog shows an array of data values for the selected dataset. From the Edit Dataset Values dialog, you can export the data values in a couple ways.

Example of the Edit Dataset Values dialog

The first option is to click the Export button in the dialog. This will open the Dataset Filename dialog. Here you can give the exported file a name and save out the data as a tabular text formatted file. This exported file can be opened with a text editor or spreadsheet program. All values in the dataset will be exported with this value.

The second option is to select the data in the data array, then copy (Ctrl+C) and paste (Ctrl+V) the values into another document such as Excel or Google Docs. This method gives you the option to be selective about which data values to include. This method also allows you to save out the data in other file formats.

It is important to note that if you change the formatting in the text file, in excel, or google sheets and try to import the file back into GMS it may not import correctly. The format used in the Edit Dataset Values dialog is the format that GMS will be expecting when importing the data back into the project.

Try out exporting dataset values using the View Values command in GMS today!

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Using Exchanges with MODFLOW 6

By aquaveo on March 9, 2022

How can you get models to run smoothly together in MODFLOW 6 in situations where boundary conditions don’t adequately describe their relationship to each other? In MODFLOW 6, you have the option of relating models to each other through an exchange instead of just using boundary conditions. This allows the MODFLOW 6 to calculate the flow between each model as if it were part of one large unstructured grid.

Connecting models through exchanges allows for the transfer of information back and forth between two models with distinct purposes and packages. GWF-GWF Exchanges create relationships between the cells of GWF Models by identifying cells where water will be exchanged between. The GWF-GWT exchange creates a relationship where the GWF Model provides the flow data that informs the GWT Model.

Example of the GWF-GWF Exchange Options

But in what situations might you use these exchanges?

In the case of GWF-GWF Exchange, the USGS has identified several situations where this could be desirable:

  • Horizontally adjacent models: It may be necessary to connect models that are in the same area in order to better describe how they relate to each other.
  • Vertically adjacent models: As with the horizontally adjacent models, it may be better to connect models that represent different layers more completely than it is to simply put all the layers on one model. This allows for variation in the fineness of the grids while maintaining communication between them all.
  • Locally refined grids: You might want to refine grids around areas where you want more specific results. Using an exchange, the simulation will calculate them all like they’re part of the same unstructured grid.
  • Periodic boundary conditions: This use aims to show the effects of repeating conditions by coupling cells on opposite sides of the model. Instead of exchanging information between cells of adjacent or circumscribing models, you can exchange information between cells in the same model that are not already adjacent to each other.

As mentioned above, the primary purpose of the GWF-GWT exchange is to provide the flow information from the GWF Model to the GWT Model. Since the GWT Model needs flow data for every cell in the model, this is a convenient way to provide that flow data. (For extended information on inputting data for GWT Models, see USGS documentation).

If you have MODFLOW 6 models that you would like to connect to each other, experiment with exchanges in GMS 10.6 today!

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