GMS

Creating a Pathline for Every Time Step With MODPATH

By aquaveo on May 30, 2023

Have you ever wanted to be able to visualize the movement of particles along every time step in a MODFLOW simulation using MODPATH? MODPATH is a program in the Ground-water Modeling System (GMS) for tracing particles that is utilized in conjunction with the flow data in a MODFLOW simulation. MODFLOW defaults to showing particle movement one time step at a time, but it is possible to show all time steps at once by making use of the Pathlines → Arcs feature.

Example of pathlines generated by MODPATH

To create the particle pathlines as arcs, you need a complete MODFLOW and MODPATH simulation. Once you have that, creating arcs to represent every time step is as simple as going to the MODPATH menu and selecting Pathlines → Arcs. This will create new coverages under your Map Data, the number of which will depend on how many Particle Sets exist in the simulation. It may be useful to go to your display settings and make sure that vertices are turned on under Map Data to see the time steps along the pathline arc more clearly. Each segment of the arc represents a single time step, with the subsequent segment starting where the previous ended.

By right-clicking on one of the particle sets, you can select View Pathline Report, which will show the same data from the arcs on a table. By doing this, you can view the exact values for each point and vertex along the pathline arc. You can also export this data as a text file, which can be opened in Excel in order to view the data outside of GMS. Additionally, you can view the data in several different types of plots by using the Plot Wizard under the Display menu.

You can also export the data from each particle set as a shapefile, making it simple to import the pathline arc data into a different project or program. To do this, all you need to do is right-click on the particle set, export the data, and save it as a Pathline Point Shapefile (*shp).

Head over to GMS and try out the different ways to visualize particle data with MODPATH and MODFLOW today!

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GMS

Filling Missing Raster Data

By aquaveo on May 23, 2023

Do you have a raster that has holes in it? The Fill Nodata can fix small holes in raster data. Available in GMS, SMS, and WMS. In this article, we will explore the ways that the Fill Nodata tool can be used in WMS.

The Fill Nodata tool fills in small areas or gaps in a raster where no elevation data exists. It is located in the Rasters/Fill Nodata section of the Toolbox. The tool will interpolate an elevation to raster cells that are classified as "NODATA". Then the tool will create a new raster in the project that has the fillable no data areas filled.

These holes in the raster can occur for a number of reasons, one of the most common being that the data is incomplete. WMS is flexible enough that it can use a raster with small amounts of missing data for most simulations. However, it is recommended that you have data that is as complete as possible to ensure the generated model is as accurate. Therefore using the Fill Nodata tool can help ensure the accuracy of your model.

The Fill Nodata tool has a few input parameters to keep in mind. The input raster is the most important parameter. This needs to be a raster that has been imported into the project. The maximum distance to interpolate determines how far out WMS will look to fill data. It will use pixel units to do this. The number of 3x3 average filter smoothing iterations to run determines how many smoothing interactions will be run after the interpolation has been calculated. Additional interactions can help in improving the fill data.

Keep in mind that the tool was not intended to create data for large regions of missing data cells, especially regions on the border of the raster. If you have a large area of missing data, it would be best to use other processes to fill in the missing data, such as downloading the missing data and merging it with your raster.

The Fill Nodata tool is one of thetools provided in WMS to let you modify and edit raster data. Try out the Fill Nodata tool in WMS today!

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GMS

Converting a 3D UGrid in GMS

By aquaveo on May 9, 2023

Have you ever had an unstructured grid (UGrid) or mesh in your project in the Groundwater Modeling System (GMS) that you want to convert to another geometry? While there isn't a specific tool for converting UGrids in GMS, it can still be achieved by following a few simple steps. Typically a UGrid will need to be converted to a scatter set and from there the scatter set can be converted to other geometries. Converting UGrids or mesh into scatter points can be a good way to compare data between models, especially if one of the models is older and doesn't, or can't, include a UGrid or mesh. If this is something that interests you, this article will explain how to get from a UGrid or mesh to either 2D or 3D scatter points.

First, go to the Display menu above the macros in the GMS window. Then choose Convert to CAD. Note: CAD data. is generated from whatever is currently visible in the Graphics window, so make sure that everything you need is displayed before you continue. The new CAD data will appear in the project window as a (*.dwg) file. Now right-click on the CAD data and convert CAD Points to TIN Points. A dialog window will appear asking you to designate which layers of the data you want to include in the conversion and to name the new TIN. You can customize this in whichever way best suits your needs.

This new TIN data can be converted directly into a scatter set. Right-click on the TIN and convert it into a 2D scatter set. 3D scatter sets can be made by simply executing a conversion one more time with the 2D scatter set.

If ultimately you want to compare scatter data with another model, it may be helpful to be able to view both sets of data in the same window. You can easily export the scatter set from GMS by right-clicking on the scatter set in the project window and selecting Export, then open the newly exported file in the GMS window with your other project. The scatter set can also be used to create a boundary for a 2D or 3D Cartesian grid which could be used with an older version of MODFLOW.

Head over to GMS and try converting UGrids into scatter sets today!

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GMS

Exploring the MODFLOW HUF Package

By aquaveo on April 18, 2023

Are you looking to control flow between grid cells in your MODFLOW project using the Ground-water Modeling System (GMS)? MODFLOW offers a couple packages for doing this, but consider using the Hydrogeologic-Unit Flow (HUF) package. This package gives you greater control over the properties of cells regulating flow in a MODFLOW model and help represent more complex stratigraphy in your project.

The HUF package is located in the MODFLOW Global options, and can be used in conjunction with other packages. The HUF package is one of the flow packages, of which you can only have one flow package selected for a project. Once the HUF package has been added to the project, it can be accessed through the MODFLOW menu.

The benefit of using the HUF package in your MODFLOW model is that the materials are not bound to the grid, making it possible for there to be more than one material mapped to a single cell. The hydrogeologic units are calculated independent of the cell boundaries, so by using the HUF package the model can more accurately represent the relationship between materials.

View the hydrogeologic units by going to the display options and clicking on the MODFLOW tab under 3D Grid Data, then turn on Hydrogeologic units. Back in the Graphics Window, when in ortho mode, you can view the model from the top, front, or side.

By accessing the HUF package under the MODFLOW menu, you can select the Edit Materials button to view or change the conductivity level of each material. In the HUF package dialog, you can also edit the top values or thickness values in the array manually, and designate whether to use vertical hydraulic conductivity (VK) or vertical anisotropy (VANI). You can also define each layer as confined or convertible, assign a head to dry cells, adjust grid elevations, and more. The HUF arrays can also be exported to grid datasets, which makes them viewable as contours or in a table.

Incorporating the HUF package into GMS also expands how the package can be used. For example, GMS has the ability to use TPROGS to generate HUF data.

Go to GMS and see how the HUF package can be used in your MODFLOW model today!

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