GMS

Tips for Using MODPATH in GMS

MODPATH is designed to work with MOFLOW to show particle tracking information. Using MODPATH can provide valuable information to your groundwater model. With that in mind, here are a couple tips for using MODPATH.

Seeing the Breakdown of Position vs Time

After running MODPATH, you can use GMS to see the breakdown of position vs time.

  • Duplicate your particle set and change the duration for each to correspond to the end of a different time step. This will help visualize when the particles traveled along their pathlines.
  • View the Pathline Report by right-clicking on a particle set in the Project Explorer and selecting the View Pathline Report command.
MODPATH Pathline Report
MODPATH Crashing During a Transient MODFLOW-NWT/UPW Simulation

While MODPATH is quite stable, it can crash when used with some MODFLOW-NWT models. To avoid this, look at the following:

  • When the water level is below the bottom of the cell in MODFLOW-NWT, making the cell dry but not inactive, MODPATH calculations give bad values. Check the cell thickness to see if it is above the water level. Then, inactivate cells above the water level.
  • The alternative workflow, which is not appropriate for every model, would be to change your MODFLOW-NWT model so that either the cells do not go dry, or are set to be inactive from the beginning, which is what this user on this forum post chose to do.
Importing Old Versions of Particle Coordinate Files

GMS has the capability to read in older particle coordinate files. Old versions of the endpoint, pathline, and time series files are automatically detected and read by MODPATH-PLOT. When old particle coordinate files are read, all time step values are automatically set equal to 1 and the particle release time is set equal to 0. The discharge code (IDCODE) for all particles is set to 1 (normally terminated).

Using these tips can increase your MODPATH expertise. Try out MODPATH using GMS today!

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Sharing GMS Project Files

As many of us work in a collaborative environment, sharing projects becomes essential. When sharing a GMS project, it is not as simple as sending over just the GMS project group file (*.gpr) project file. GMS projects are stored in multiple separate files that work together. When sharing a GMS project, it is important to include all of the necessary files.

GMS projects are saved as a project group file (*.gpr). This file saves feature objects, projection data, data objects and other general settings. However, it only references many other aspects of a project that are contained in separate files. It will reference the location of all external files such as shapefiles (*.shp, *.dbf, *.prj, etc.), images, CAD files, grid files, etc. When sharing a GPR file, the file needs to be able to locate these external files. Ideally, these files should be located in the same folder as the GPR file. This is why it is recommended to zip all the project files together before you send it out to be shared.

GMS project files

When your project contains a MODFLOW model, it is important to know that GMS saves the MODFLOW project in separate files. For example, each package saved as a different file. Rivers (*.riv), drains (*.drn), wells (*.wel), streams (*.str), recharge (.rch), etc. are all different packages with different file extensions. Sending over just the package file, such as only sending a wells file, is not much use as GMS will likely be unable to open it.

Along with the MODFLOW package files, GMS will need the MODFLOW name file (*.mfn). This file allows GMS to build the MODFLOW project when it is imported. All other input and output MODFLOW files should be included when sharing your GMS project.

Note that many files will be saved in a folder created next to the GPR file. Files in the folder should be left there and the entire folder should be moved with the GPR file. GMS saves the relative location of files included in the project.

When sharing your GMS project, keeping all of the necessary files together can save the person receiving the project a lot of frustration. For more about GMS file formats, be sure to check out the GMS articles on the XMSWiki and start sharing your GMS projects today!

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Tips for Exporting a MODPATH Project

MODPATH works with MODFLOW to show particle tracking information. Once you have successfully completed a MODFLOW project, you may want to share that information collected through MODPATH with your other colleagues. Exporting the MODPATH data can allow you to share specific information with them.

Typically, the Save As command in the File menu and the right-click Export command in the Project Explorer are used to export MODPATH data from GMS. When using these commands, there are some tips for getting the most out of them.

Exportin MODFLOW
Exporting MODPATH Flowlines to a KMZ File

The flowlines from a successful MODPATH run can be exported as a KMZ file using the Save As command. When doing this, pay attention to the following:

  • Use the Display Options to make the flowline more visible before exporting to a KMZ file.
  • Make certain that the projection/coordinate system of your MODPATH project has been set correctly. KMZ files require that a coordinate system be set therefore GMS cannot create a file if there is no projection.
  • Objects in the Project Explorer can be set to different projections. Be certain to review the projections of all objects when exporting a KMZ file.
Exporting Points

Using the Save As command, the particle points of the MODPATH project can be exported to a shapefile.

  • When exporting particle points from MODPATH it is important to note that endpoints will need to be exported with intermediate points.
  • Another option is to use the Text Tab Delimited Pathline File option, which prints out the location and could be quickly parsed to pull the X and Y locations for the last time step of each particle.
  • MODPATH output can be exported to a shapefile or text delimited file by right-clicking on your MODPATH particle set in the Project Explorer and selecting "Export".
  • In the "Export Particle Sets" dialog that comes up, you can then change the "Save as type" option at the bottom to the type (pathlines, points, vectors), and format (shapefile, text delimited file) you prefer.

Many of these tips apply to exporting other numeric modeling data in GMS. Try out the different export functionalities in GMS today!

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3 New Features in GMS 10.5 Beta

We are happy to be announcing the beta release of GMS 10.5! Thanks to the hardworking developers here at Aquaveo there are a number of new and exciting features to this new version.

To name a few, we gathered a list of three new and improved features in GMS 10.5 beta release!

  1. MODFLOW 6 Grid Approach
    Additional functionality has been added for working with MODFLOW 6. A MODFLOW 6 model can now be built in GMS using the grid approach. The new MODFLOW 6 interface uses a simulation approach that is different from the interface for other MODFLOW applications in GMS. This approach also allows for multiple simulations to be included in a single project.
  2. TVM Package
    The TVM package is now available in GMS 10.5 for use with MODFLOW-USG Transport. The Time-Variant Materials (TVM) package allows the changing of hydraulic conductivity and storage values between stress periods. Through a transient simulation, it can also be used to change these parameters in a continuous manner not just in increments between stress periods. This will help display the different changes made to the project over time.
  3. TVM Package in GMS 10.5
  4. Tile map services (TMS) can now be used for import or background image display.
    In this new version of GMS the ability to import TMS into projects needing tile map services has been made available. This provides access to maps that can now be rendered to map tiles at fixed scales. Rather than trying to break down one large image, this helps to be able to view a map in a simpler way. It also helps to be able to pinpoint and save one particular tile of a map in case only that tile is needed as opposed to the entire image.

These are only some of the changes that have been made to the new beta release version of GMS. Explore even more of the changes by downloading GMS 10.5 beta from our downloads page.

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