GMS

Having Multiple MODFLOW 6 Simulations in GMS

Have you tried including multiple MODFLOW 6 simulations in your GMS project? Having multiple MODFLOW 6 simulations allows you to run simulations for the same area. This can help with calibration, making comparisons, and troubleshooting a model. This post will cover how to keep things organized when using multiple simulations in a single project file.

After you have created a second MODFLOW 6 simulation, it is recommended that you give the simulation a name that will help you remember the purpose of that simulation. For example if you have a base simulation that you are using to create a stable starting run, it could be named something like “Base_Sim”. If you then create a second simulation that has a longer run time, naming it something like “Base_Longer_Run” might be helpful.

Furthermore, you can use the Notes feature available in the simulation properties dialog to add notes about what makes each of the simulation unique. This can be particularly helpful when sharing the project with coworkers.

In some cases you may have multiple UGrids. For example, you may want to use one UGrid that is less refined for a simulation for a base simulation and a more refined UGrid to test with a duplicate simulation. When doing this, be certain to correctly name the UGrids so that they are easy to tell apart. Also, make certain the UGrid is linked to the correct MODFLOW 6 simulation. It is usually best to create a separate simulation for each UGrid.

Often when using multiple simulations, you will want to have specific map coverages applied to specific simulations. When doing this, you can organize your coverages in the Map module using folders. Using folders can help keep straight which coverages belong with which simulation. And can also help in keeping the Project Explorer from becoming cluttered.

Example of Multiple MODFLOW 6 Simulations in GMS

In the Project Explorer, collapse any folder that you are not currently using. This will help keep the Project Explorer free of any unnecessary clutter. This is particularly helpful when you have solution data from different simulation runs. GMS will automatically place simulation solution files in their own folder in the Project Explorer under the UGrid connected to that simulation, as well as as links under the simulation. Additional folders can be added to organize solution data.

Also, when working with multiple simulations, it can be helpful to lock simulations that are not currently being worked on to reduce chances of accidentally making changes to the wrong simulation.

It should also be noted that having too many simulations in a project can cause GMS to run slowly. It is typically recommended to have fewer than seven simulations in a project.

Having multiple MODFLOW 6 simulations in your project expands your groundwater modeling options. Try out using multiple MODFLOW 6 simulations on your project in GMS today!

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Defining Hydraulic Conductivity for Specific Layers

In your groundwater model, do you need to define hydraulic conductivity for specific layers differently than other layers? Do you need to modify the hydraulic conductivity values for specific areas within a single layer? GMS provides more than one way to assign hydraulic conductivity. This capability gives you more precision with regard to how hydraulic conductivity is assigned to your groundwater model.

Using the conceptual model approach, hydraulic conductivity can be assigned to polygons on a single coverage then mapped to your model. You can also use multiple coverages, assigning the hydraulic conductivity to specific layers ranges. The workflow for this is as follows:

  1. Right-click on the coverage and select "Coverage Setup...".
  2. In the "Default Layer range" set the layer range you would like to use.
  3. Coverage setup for conductivity on a specific layer
  4. Select the coverage to make it active.
  5. Double-click on a polygon within the coverage.
  6. It will bring up the attribute table for that group of layers.
  7. Set the conductivity for the polygon.
  8. Repeat this process for each desired group of layers.

When using this workflow, take care to make certain you are setting the correct attributes to the correct layer of your grid. Naming the coverage with the layer number or layer range can help with this process. You may also want to use the notes feature to attach reminders as to how the coverage has been set up.

It should be noted that when mapping multiple coverages to your grid, GMS follows an order of priority for the coverages. If you have different conductivity values on different coverages that overlap it is recommended that you apply the coverages individually. The last coverage that you apply will overwrite any overlapping values. If you apply all the coverages at once, the conductivity values will be summed up in areas where they overlap.

Try out using multiple coverages to define hydraulic conductivity for specific layers in GMS today!

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How to Export Contour Lines as Shapefiles

Have you been wanting to export the contour lines in your GMS project as a shapefile so they can be opened in a different application? GMS allows exporting contour lines as a shapefile. Shapefiles are a file format used by many different GIS software applications. This post will explain how to export contour lines as shapefiles.

GMS contains the Layer Contours → Shapefile command to help save contour lines as a shapefile. Using this command requires your project to be set up correctly. Use the Layer Contours → Shapefile command by doing the following:

  1. Make sure the contours you want to convert to a shapefile are set to Linear in the Display Options. This can be accomplished by opening Display Options and clicking on Contours. In the Contour Method in the top left make certain in the dropdown that it is set to Linear.
  2. Make sure your Grid module is active in GMS, this can be done by clicking on the grid in Project Explorer or selecting the Grid module macro. The grid should be highlighted, meaning that it is now active.
  3. Go to the Grid menu and select the Layer Contours → Shapefile command. Use the dialog that appears to save your shapefile. Be sure to place it in the correct folder and name it properly. Otherwise you might lose the file.
  4. Now open your shapefile in the appropriate GIS software. The contour lines will appear as arc lines.
The Contour Lines to Shapefile Command

If you encounter issues with the shapefile, start with checking the folder where you saved the file. Make certain that all of the necessary files for the shapefile are there, including a projection file. Another item to check is that everything you want in the shapefile is displayed correctly in the Graphics Window before you export. Use the display options to adjust the contour lines if needed. Finally, there may be some differences between how GMS displays a shapefile and how other GIS applications display the shapefile. Opening the shapefile in GMS can help you determine if this is the case.

Try out converting contour lines to shapefiles in GMS today!

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New Features in GMS 10.6 Beta

Aquaveo is pleased to announce the release of the Groundwater Modeling System version 10.6 in beta! With this beta release, GMS contains changes and improvements to various features, much of it involving increased support for MODFLOW 6 functionality. We’d like to highlight some of the new functionality you can expect to find in GMS 10.6 beta.

Transport Support for MODFLOW 6

GMS 10.6 beta adds the ability to work with transient models for MODFLOW 6, as demonstrated by the addition of transport packages relevant to the GWT (Groundwater Transport Model) package. These will be helpful to many different aspects of groundwater transport modeling, such as dealing with advection, constant concentration, and dispersion. With the wealth of packages this alone adds to GMS 10.6 beta, it will add a lot of functionality to what GMS can do with MODFLOW 6 simulations.

Example of the new MODFLOW 6 Simulation dialog
Increased GWF Package Support MODFLOW 6

In addition to the suite of transport-related packages that GMS 10.6 adds to work with, support has also been added for more packages relevant to the GWF (Groundwater Flow Model) package. In this case, this includes the addition of the BUY (Buoyancy) and CSUB (Skeletal Storage, Compaction, and Subsidence) packages. The addition of these packages will help flesh out what GMS 10.6 beta can do with MODFLOW 6 simulations.

Support for Exchanges in MODFLOW 6

Support has also been added in GMS 10.6 for exchanges. These include the GWF-GWF and GWF-GWT exchanges. These can be used to help different models in a GMS project interact, and designate the nature of how they should interact. GWF-GWF exchanges can help two different GWF models interact together and hydraulically connect, telling each model that there is flow along a shared edge. GWF-GWT exchanges can help designate which GWF and GWT models should interact with each other.

These are just a few of the new features and changes coming out as part of the release of GMS 10.6 beta. You can find more information on what will be introduced in GMS 10.6 beta by going to the Aquaveo XMS Wiki. Try out these features and more by downloading GMS 10.6 beta today!

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