Aquaveo & Water Resources Engineering News

Using Top Elevation Data for Starting Head Values for MODLOW 6

The Ground-water Modeling System (GMS) includes multiple methods of setting the starting heads in the Initial Conditions (IC) package for MODFLOW 6. Starting with GMS 10.8, you can use the top elevation data already entered in the Discretization by Vertices package (DISV) for your starting head values without any extra steps.

When you open the Initial Conditions (IC) dialog, it shows several options for setting the starting heads. For simple models you can set a constant value for starting heads across the entire grid. But for more complex models, you'll want values to better represent the test area. This often means you have to either manually enter, copy and paste, or import from another data file.

However, doing this sometimes involves duplicated work you might have already completed in the DISV package. To eliminate this inefficiency, GMS 10.8 has added a new method that allows you to use the DISV top elevation data as your starting head values. This can be done using the following steps:

  1. Open the Initial Conditions (IC) dialog.
  2. Check on the box that says "Set starting heads equal to cell top elevations."
Starting head equal to cell top elevation option

Turning on this option will match the starting heads to the elevation data already imported or entered in the DISV package and grays out all other parts of the dialog.

Using this option, the top elevation data will be used as the starting head values during the MODFLOW 6 simulation run. Setting the starting heads equal to the top elevations in GMS offers some benefits:

  • It provides an additional option for inputting the starting heads data.
  • It can save you time by using data already in the model.

As always, it is best to review the data before running the simulation and after running the simulation to verify that the values were incorporated correctly.

Now head over to GMS 10.8 and check out using your top elevation data as your starting heading values in your MODFLOW 6 projects today!

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Managing File Paths in WMS

When working in the Watershed Modeling System (WMS) the software refers to multiple applications and files in order to operate correctly. The default settings for accessing these files should generally be followed. However, there are times when these file paths need to be altered by you or the paths get changed unintentionally. This post will go over some of the important file paths to pay attention to in WMS.

Typically, WMS will be installed on your C drive or whichever drive you specify on your local machine. When WMS is installed, it will also install multiple other applications that it uses. These are most often the numerical models that WMS uses along with some drivers. WMS will keep everything contained to where it can find these applications.

However, to give you more flexibility, WMS allows you to change the location of these applications. Most path locations can be changed in the Preferences dialog. The Files tab of the Preferences dialog contains the file paths for the numerical models and other applications. The file paths can be changed here to direct to a different location. This can be useful when you are needing to use a different version of a model executable other than the one that comes installed with your version of WMS.

File paths set in WMS

The Preferences dialog also allows you to change the file path for the Temp directory. This is done on the General tab.

It should be noted that WMS retains these file paths once they have been set. Therefore, when you are moving files around, pay attention that WMS will not automatically update to the new location. When a model executable gets moved to another directory, you will need to manually update the file path in WMS in order to avoid potential errors.

The Files tab of the Preferences dialog is also useful for locating specific model executables and files that you suspect may need to be updated. This can help you troubleshoot model executable issues that occur during a model run.

Now that you know more about how WMS manages file paths, make use of them in your WMS projects today!

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Taking Advantage of the SRH-2D Channel Calculator

The Surface-water Modeling System (SMS) provides a useful tool that generates an estimated water surface elevation on an "Exit-H" boundary condition in an SRH-2D model. The Channel Calculator in SMS makes it easier to calculate water surface elevation values. It also gives you greater control of over the parameters

When building an SRH-2D model, the exit boundary will need to be defined. A constant elevation is often used, but this can not be sufficient in many cases. The Exit-H boundary condition is a stage type exit boundary where water surface elevation may be given as a constant number or as a stage-discharge or rating curve. The Channel Calculator is used to compute and assign a normal or critical water surface elevation for the outflow boundary condition. It also gives you greater control over the parameters used to determine the outflow conditions.

Example of the Channel Calculator in SMS

The Channel Calculator is accessed through the SRH2D Assign BC dialog. The Populate using Channel Calculator button appears at the bottom of the dialog when "Exit-H (subcritical outflow)" is selected as the BC Type and the Water Surface Elevation option has been determined.

The Channel Calculator specifies a composite roughness value, slope, and flow. SMS extracts a ground elevation cross section from a specified underlying elevation data source (mesh) that is used to compute the area and wetted perimeter. The calculator can make use of different types of elevation data sources which include DEMs, meshes, and scatter sets. Roughness and slope values will be required for the final calculation. Other options, such as the WSE offset, are optional and should only be used when necessary for your project.

The Channel Calculator will display a preview of the exit area cross section with normal and critical depth. When the Channel Calculator will save the values entered when exited. The values in the calculator can be changed later if needed.

The Channel Calculator in SMS gives you a useful tool for determining exit water-surface values for your SRH-2D projects. Try using it in SMS today!

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Utilizing MODFLOW Symbols Display Options

The Groundwater Modeling System (GMS) has many different options for customizing the display of your project. One display feature created for MODFLOW in GMS is the ability to use symbols to represent the properties of individual cells. This can be quite useful especially for more complicated MODFLOW models. You can use the MODFLOW symbols in the Display Options dialog to represent things like rivers, lakes, wells, drains, and more.

Example of MODFLOW symbols in GMS

You can find the MODFLOW display options as their own tab by selecting the corresponding grid from the list on the left side of the Display Options dialog. The MODFLOW symbols all have a default shape, size, and color. The shape, size, and color of the symbols can all be customized by clicking the button to the left of the checkbox. The ability to customize the MODFLOW symbols is a useful feature for everyone, but especially our users who are visually impaired or color blind. For the best results, the symbols should be set to something different enough from each other that it is easy to tell which is which at a glance.

If you use the MODFLOW symbols in your project, you should consider turning on the display symbol legend. The legend shows a list in the corner of the Graphics Window of all of the MODFLOW cell properties contained within the current project, making it easier to keep track of what everything means. Only symbols that exist in the layer being viewed will appear in the legend.

There are a few additional symbol display options for MODFLOW on the Map Data section of the Display Options dialog. A list of the symbols appears when MODFLOW is selected from the Coverage dropdown. These symbols are specific to properties on the coverages in your project, and they can be customized in the same way as the symbols under the MODFLOW tab of the grid in the Display Options dialog.

Open GMS and use the MODFLOW symbols in the display options to help you keep track of the properties of your MODFLOW project today!

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