GMS

Using A Well Pumping Rate to Calibrate a Model

By aquaveo on August 11, 2021

Have you needed to know how to use a well pumping rate as a calibration parameter in a PEST run? For example, this might be useful in estimating a probabilistic capture zone. We have a workflow that can help with this, utilizing an extraction well and the WEL package for model calibration. This post will review how you can set your MODFLOW parameters in GMS to incorporate well information to be used for parameter estimation.

To do so, use the following steps:

In a well coverage, create a well and give it a constant pumping rate (negative for extraction).
Go to MODFLOW | Parameters... to bring up the Parameters dialog and click the New button to create a new parameter.
Turn on the Show all columns checkbox at the top of the dialog and change the Type value to WELL.
Enter the value that was used for step 1 as the Key, and enter its inverse as the Value.
Enter values for Min and Max that are greater than 0.0. These values and Value will be multiplied by the Q factor later on, which will be -1.0, so positive values listed here will actually become negative.
Turn on the Log Xform checkbox and close the dialog.
Go to MODFLOW | Optional Packages | WEL - Well… to bring up the MODFLOW Well Package dialog.
Enter a Q factor of -1.0 and close the dialog.
Go to MODFLOW | Global Options… to bring up the MODFLOW Global/Basic Package dialog.
Under the Run options section, select Parameter Estimation and close the dialog.
Create a new Observed Flow coverage with Observation Points set to Head in the Coverage Setup dialog, and create a head observation with the Map module active.
Save the project and then click Run MODFLOW to run the PEST Parameter Estimation. When the run is complete, make sure to read the solution into your GMS project.

Example of PEST running using pumping rate as a parameter

Following the above steps will generate solution data where you can use any of the post-processing tools in GMS to review and adjust your model. Try out using well pumping rates in model calibration in GMS 10.5 today!

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GMS

Mapping Multiple Coverages in GMS

By aquaveo on July 21, 2021

Do you have a conceptual model project in GMS where you have multiple map coverages with values for the same MODFLOW package? Are you wondering how GMS maps values from multiple coverages over to the MODFLOW packages?

It's not unusual for some projects to require the same attributes to be in separate coverages rather than having all the attributes in a single coverage. For example you might want to use recharge attributes from different sources and have placed the values on different coverages. But how exactly does GMS handle this? This post should hopefully give you a better sense of what GMS is doing behind the scenes.

Normally, the values for a particular MODFLOW package, such as recharge, are placed on one coverage that uses multiple polygons. In this case, a single value can be calculated, taken only from the predominant polygon, as it is expected that the polygons will all be within the same coverage. Also in this case, the methodology is designed to accommodate polygons being used to calibrate recharge zones in PEST, as opposed to calibrating with pilot points. If using gradient recharges, it is recommended to use scatter points to interpolate recharge values to MODFLOW layers.

You may have a case where you have the values for a package, such as recharge, on polygons on different map coverages. This could be because you imported the values from different sources. In cases where the polygons on different map coverage overlap, the attribute types with different values will have those values summed up when they are applied all at once if you map all of the coverages at the same time. If you don’t want them summed up, make sure that rather than applying them all at once, the value you want is the last value mapped over. This is because when multiple coverages are applied at once, GMS sum the values cumulatively, but when done individually, GMS overwrites the value with the most recently mapped coverage.

It is important to note that hydraulic conductivity is not cumulative, though the sources may be. Hydraulic conductivity is overwritten every time, so the values MODFLOW receives are the values of the last polygon that intersected an individual cell.

Items in the Project Explorer are mapped in descending order, so changing the order of the coverages can change the end results.

You can also find more information on how objects are mapped to MODFLOW at the Aquaveo XMS Wiki.

Try mapping multiple coverages in GMS 10.5 today!

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GMS

Converting External 3D Materials to 3D Grid Materials

By aquaveo on June 30, 2021

For your 3D grid project in GMS, do you have material data from a 3D mesh or other geometry that was created in an application other than GMS? It is possible to import this data into GMS and attach it to your 3D grid using a method which involves creating solids that GMS can use to assign materials. This is done by importing the data as boreholes and creating solids from them. This post will review how you can take the material data from a 3D mesh and transfer it to a 3D grid in GMS.

To do so, do the following steps:

First, you will need to import the material data as Borehole data into GMS.
You will then need to create horizons for these boreholes. Go to Boreholes | Auto-Assign Horizons.
In the Auto-Assign Horizons dialog, choose Start from scratch, then click Run. The Horizon Optimizer dialog will appear. This step will take a while to complete.
When complete, click "Read solution on exit" and click OK to close out of the dialog.
Once the Horizons are defined, click Boreholes | Auto-Create Blank Cross Sections.
Once blank cross sections exist, click Boreholes | Auto-Fill Blank Cross Sections.
In the Auto-Fill Blank Cross Sections dialog, select what should be matched from the auto-fill options based on the needs of the project.

Cross sections created from borehole data

Create a new coverage, just using the defaults should be fine in most cases.
Using the Plan View and the Create Arc tool, create a closed arc surrounding all of the boreholes.
Select Feature Objects | Build Polygons, to turn this closed arc into a polygon. You might also want to use the Redistribute Vertices command on the arc if needed.
Turn this polygon into a TIN by using Feature Objects | Map → TIN to define the desired boundary of the solid.
Finally, create solids from the boreholes by selecting Boreholes | Horizons → Solids. This will bring up the Horizons to Solids dialog where you can choose your desired settings.
The solids can then be used to classify the materials zone in place of the mesh.
If the solids are needed in another project, you can highlight one or more of the solids in the Project Explorer, right-click, and Export them as a *.sol file.

Try out using this workflow to add data to your projects in GMS 10.5 today!

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GMS

How to Troubleshoot Graphics Card Issues and Display Issues

By aquaveo on June 23, 2021

Out of all the potential issues that can come up, display issues can be some of the most annoying. Display issues can come from individualized hardware configurations, display settings, operating system and software versions which makes solving these issues not as simple as a one-size-fits-all approach. This post will review general best practices for troubleshooting these kinds of issues with your graphics card or display.

Some of the most common display issues that can arise with XMS are problems with one or more of the following:

Transparency
Functional surface
Texture mapping
Film loops
Contours

The causes behind display issues can be divided into the following categories:

Issue related to remote desktop or virtual machine
Integrated graphics used instead of discrete graphics
Bug in graphics drivers
Limitation of integrated graphics
Bug in XMS affecting all hardware configurations
Bug in XMS affecting specific hardware configurations

Since hardware configurations vary and operating systems change over time, the information here is a general workflow used for troubleshooting.

Remote and Virtual Machine issues: Check if XMS is being run locally or if a virtual machine/remote desktop is being used to rule out Category A.
Versioning: Go to Help | About to note the XMS version, build date, and graphics library used.
Try to rule out Categories E and F: Run XMS in Software Graphics Mode. If the issue is resolved in Software Graphics Mode, then the issue is related to Categories B - D.
Try to rule out Category B: Go to the Device Manager for the Display Adapter. If the driver information/version for the discrete graphics matches what is shown in Help | About, then XMS is using discrete graphics. If not, go to Step 6 to ensure XMS is using discrete graphics.

Update graphics drivers: Whether or not the system has discrete graphics, updating the graphics driver will solve some display problems. If the machine already has nVidia or AMD software installed, drivers can be updated through those programs. Otherwise, click the “Update Driver” button (shown in the dialog in Step 4) or Google “GraphicsCard Driver Download” using the graphics card model you have in place of GraphicsCard. Exercise caution with the links you click on. Be sure to click on official AMD, nVidia, or computer manufacturer websites. Avoid 3rd party utilities that offer to optimize your system or install adware/spyware.
Set system to use discrete graphics: Change settings to ensure XMS always utilizes discrete graphics. Many systems, especially laptops, default to power saving modes where programs utilize integrated graphics even if the machine has discrete graphics. The way to change these settings varies by machine.
Reporting Bugs: If Categories A - D have been ruled out, determine if the issue is machine-specific. If reproducible, report to tech support.