Aquaveo & Water Resources Engineering News

Exploring the MODFLOW HUF Package

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.

Example of HUF package materials

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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Using CAD Data to Delineate a Watershed

Did you know that you can use CAD files to delineate your watershed area in a Watershed Modeling System (WMS) project? WMS is capable of using CAD data for elevation data, designs, layouts, and more. CAD data can be converted to TINs and feature objects to be implemented in a WMS project.

When converting the CAD data to feature objects, you can choose which layers from the data you would like to use when creating the new feature object. After that, you can clean up the feature object and choose all the properties for the coverage. To convert CAD data into feature objects, do the following:

  1. Import the CAD data into WMS from a DWG, DXF, or DGN file.
  2. After importing the CAD data, review the data to verify that it was imported correctly and that it has the correct projection.
  3. Right-click on the file in the Project Explorer and select Convert | Feature Objects….
  4. In the Cad → Feature Objects dialog, select which layers to convert into feature objects.
  5. Make certain the new coverage is set to have the "drainage" type.
  6. Designate the converted feature objects as outlet points and streams. Also verify that any stream arcs a set with the correct direction.

With the CAD data converted to feature objects and you've designated your outlets and streams, you can start the process of delineating your watershed. To do this, you will need a DEM in your project. If you have elevation data stored in a CAD file, you will first need to convert the CAD data to a TIN.

Basin delineated from CAD data

CAD data can be converted into TIN points or TIN triangles, but the best way to end up with TIN triangles is to convert into TIN points first. To convert CAD data directly into TINs, do the following:

  1. Import the CAD data into WMS in the form of a DWG, DXF, or DGN file.
  2. Right-click on the file in the Project Explorer and select Convert | CAD Points → TIN Points.
  3. In the Cad → TIN dialog, select which layers to convert and the name the TIN data will appear under in the Project Explorer.
  4. Right-click on the TIN point data in the Project Explorer and select Triangles | Triangulate.

From here you can convert the TIN to DEM if necessary. The TIN module in WMS has a few tools for working with basins that may be sufficient for your model. However, some models either perform better or require a DEM. Once you have the DEM you can generate the delineated basin. To do this:

  1. Right-click on the TIN and select Convert | TIN → DEM.
  2. Enter parameters for the DEM in the Convert TIN to DEM dialog.
  3. Review the generated DEM.

Once you have a DEM, complete the following steps:

  1. Select DEM | Compute Flow Direction in the Drainage module.
  2. Select DEM | Polygon Basin IDs →> DEM in the Drainage module.
  3. Select DEM | Compute Basin Data in the Drainage module.

Once you have a delineated basin, you can use the basin with the watershed modeling model of your choice. Be certain to review the basin to make certain it contains all of the area you need for your project.

Head over to WMS and see how you can utilize CAD data to create delineated basins in your projects today!

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Methods for Redistributing Vertices

The ability to redistribute vertices along an arc can be essential for any number of projects. The Surface-water Modeling System (SMS) offers a couple of different methods for redistributing vertices. This post will examine two of those methods.

The Redistribute Vertices Dialog

The first way to redistribute vertices is relatively simple. Select an arc, or multiple arcs, and either right-click and select Redistribute Vertices from the menu, or go to the Feature Objects menu and select the Redistribute Vertices command. This will pull up the Redistribute Vertices dialog window. From there you have a few different options as to the method of distribution.

  • Specified spacing: the number of vertices on an arc will be determined by how far apart the vertices should be.
  • Number of segments: how many pieces the arc should be broken up into.
  • Min/max spacing: with min/max spacing, the segments will start at the minimum set length and gradually get longer until the last one is the maximum set length.
  • Source arc: this requires you to choose two arcs. The number of vertices on the target arc will change to match the source arc.
  • Size function: this option requires a data source.
Example of the Redistribute Vertices dialog in SMS

In the Redistribute Vertices dialog you can choose to include a bias with specified spacing and number of segments options. Using a bias means that each segment will be a percentage larger or smaller than the one before it, which depends on whether or not the bias number is less or greater than one. The direction of the bias is determined by the direction in which the arc was created. For example, an arc created top to bottom will have the smallest segment at the top and the largest at the bottom if the bias number is greater than one.

The 2D Mesh Polygon Properties Dialog

Another option available in SMS is to use the 2D Mesh Polygon Properties dialog when redistributing vertices along the arcs of a polygon. This can be used on any polygon that has been created on a coverage. There are three ways to access the 2D Mesh Polygon Properties dialog window, but the simplest option is to double-click on the polygon itself.

Example of redistributing vertices with the 2D Mesh Polygon Properties dialog in SMS

The 2D Mesh Polygon Properties dialog window is primarily used for creating a mesh inside a polygon. However it can still be used to redistribute the vertices along an arc. The benefit of using the 2D Mesh Polygon Properties dialog window rather than Redistribute Vertices is that it offers a preview option so you can see what the polygon will look like with the new vertex distribution without having to open and close the Redistribute Vertices dialog to see the changes. This makes it easy to test out different options right in the same window. The downside of using this dialog window rather than Redistribute Vertices is that it doesn’t offer the same range of redistribution options. The only redistribution options the 2D Mesh Polygon Properties dialog offers for vertices is specified distribution along the arc, with or without a bias. If you’re looking for more specificity, this may not be the right option for your project.

Try the different methods of redistributing vertices in the SMS today!

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Setting Up a Cross Section Animation in GMS

Have you ever wanted a way to better visualize cross sections in your project? The Animation Wizard in the Ground-water Modeling System (GMS) can help you do just that. Any project involving a 3D mesh or 3D grid can utilize the cross section animation feature.

To build your initial cross section, you’ll need to start with a 3D mesh or grid as a foundation. After your foundation is set, build the cross section. Keep in mind that the Animation Wizard will create the animation through what is currently visible in the Graphics Window, so it is a good idea to get the display settings where you want them before starting the animation process.

Go to the Display menu and scroll down to the bottom to find the Animate option. Before initiating the animation, make sure that the cross section is active in the Graphics Window. Note that although the cross section needs to be active to create the animation, it doesn’t need to be turned on if you don’t want the static cross section from the project to be visible.

Example of the setting up a cross section animation in GMS

In the Animation Wizard dialog, turn on Cross-sections/Isosurfaces under Steady State. This is the option that animates the cross sections. You can change the speed of the animation by altering the number of frames per second, which is on the first page of the Animation Wizard, and the number of frames, which is on the second page. The lower the number of frames per second, the longer the animation will spend on each cross section, and vice versa.

The second page of the Animation Wizard is where you can specify the plane over which the cross sections will be animated. You can animate over the X, Y, or Z-axis, or any combination of the three. You can also alter more of the display options for the animation under the Cross Section Option button on this page.

After clicking Finish, the Animation Wizard will automatically export the cross section animation as an MP4 file, and you can open the MP4 file to view the finished product.

Even more settings and options are available that were not covered in this post, explore what cross section animations can do for your GMS project today!

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Using the Blend Arcs Tool

Sometimes it may be useful to have a quick way to create an arc that lies between two other arcs. For example, you might need to quickly create a centerline arc between two bank arcs. The Surface-water Modeling System's Blend Arcs tool, which is new to SMS in version 13.2, means that creating a blended arc is only a few clicks away.

There are many applications for the Blended Arc tool in SMS. As mentioned earlier, it can be used to find the centerline of a channel using the bank arcs. It can also be used for a quick way to find the arc in the center of a bridge, culvert, or weir.There are many other potential applications for this tool.

Example of the Blend Arc command

The steps to use the blended arc feature are:

  1. Create two arcs. The arcs can be parallel to each other, or even touching.
  2. After selecting both arcs, right-click in the graphics window and choose Blend Arcs from the menu.

The blended arc is immediately generated. This can only be done with two arcs, however the two arcs you pick don't have to be right next to each other. You can still find the blended point of two arcs that are separated by other features, such as other individual arcs or polygons.

When working around polygons in your project, If a polygon has been created in the space where the blended arc will appear, when the Blend Arcs tool is used, the polygon will retain its original shape despite the fact that there is now an arc splitting it. This could be useful for your project, but if you intend for the new arc to split the polygon into two new shapes, you only need to click the Build Polygons macro one more time and the new polygons will be created with this new division.

Try the new Blend Arcs tool in SMS 13.2 today!

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Engineering with Nature in SMS

Aquaveo has joined in the Engineering with Nature (EWN) initiative started by the U.S. Army Corps of Engineers by adding Engineering with Nature tools into the Surface-water Modeling System (SMS). EWN aims to move toward a more efficient, sustainable, and resilient approach to engineering by considering social, environmental, and economic impacts. To support the mission of EWN initiative, SMS has developed multiple tools. Let's look at some of these tools.

Adding engineering features into your project can sometimes be a long and tedious process. With the EWN Features tool in SMS you can streamline the process, reducing the amount of time that would have been spent inputting the necessary data before. The EWN Features tool is built especially for creating feature objects to represent structures in natural environments. To use the tool, create a new map coverage and select the EWN Features type in the Engineering with Nature folder under the list of Model types to begin building structures into your SMS project.

Once you have a EWN Features coverage, you can create polygons to model the feature. You then can assign attributes and properties to the polygon. Once you have the feature properties defined, you can use the tools in the coverage to insert the define feature into a 2D mesh or 2D unstructured grid (UGrid).

Example of the EWN Polygon Properties

Another EWN tool is the Sediment Volume Management tool. The Sediment Volume Management tool allows you to calculate cut and fill for sediment volume. Like the EWN Feature tool, this tool is accessed by creating a new map coverage with the Sediment Volume Transport type found in the Engineering with Nature folder under the list of Model Types. In the coverage you can create polygons and assigned sediment parameters. Then the sediment volume calculations can be performed using the tools in the coverage.

Additional EWN tools are in development for SMS. Look for them in future releases of SMS. In the meantime, try out using EWN in SMS today!

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Using Bias When Creating a 3D Grid

Sometimes when creating a 3D grid in the Ground-water Modeling System (GMS) you may want to include a bias in the grid for your project. Using a bias parameter will refine part of the grid along a particular axis. Here are some important things to know when implementing a bias into the grid.

All of the data fields necessary for this function will be in the Create Finite Difference Grid dialog window, which appears when a new grid is created. It is here that you can customize the X, Y, and Z-Dimensions to include your bias. The starting point for the bias is determined by the cell number designated in the Origin field of each dimension, and the bias will run along the axis in the positive direction. You can input a different value for the bias in each of the dimensions.

Example of the Create Finite Difference Grid dialog showing the bias option

For a value greater than one in the bias field, each cell will be a percentage larger than the one previous. For example, a bias of 1.2 will mean that each cell following the origin is 20 percent larger than the one previous. These cells will grow in the positive direction along the axis. To make each cell following the origin smaller than the one previous rather than larger, make the bias less than one. For example, a bias of 0.8 will mean that each cell will be 80 percent of the size of the previous cell.

Example of bias used on a 3D grid

The length field in each of the dimensions determines the total length of the dimension. All of the cells on that axis will fit inside that measurement. After specifying a length, there are two options for how GMS will calculate the size of the cells including the bias. First is by the number of cells in each axis. The grid creator will calculate how big each of the cells must be in order to fit that number into the specified length.

The second option for determining cell size is to input a value for the dimension of the starting cell. For example, setting the cell size to 10 feet will tell the grid creator that the origin cell should be 10 feet, and each cell following should be a percentage larger than the origin cell until the entire length of the axis is filled. This can be refined even farther by specifying a cell size limit, keeping a cell from growing larger than a specified size. Because of this, the cell size limit should be set to a number larger than the base cell size.

With GMS, there are many ways to customize a 3D grid. Give the grid bias function in GMS a try today!

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Using NetCDF Data with AHGW Pro

Have you needed to use netCDF files with Arc Hydro Groundwater Pro? NetCDF files are intended to provide standardization to multidimensional scientific data. These files can be imported and used in ArcGIS Pro and are compatible with Arc Hydro Groundwater Pro. However, they must first be converted using ArcGIS Pro geoprocessing tools.

ArcGIS Pro has a few tools specifically dedicated to manifesting netCDF data as a familiar data form in ArcGIS Pro. These data forms include feature layers, rasters, and tables. Once netCDF data has been converted, it can be used with any Arc Hydro Groundwater Pro tool that accepts the given data form.

The ArcGIS Pro tools for netCDF data are found in the Multidimension Tools Toolbox. There's a toolset devoted to netCDF data, but some of the other tools in the Multidimension Tools toolbox will also work with netCDF data.

Example of ArcHydro Groundwater Pro greodatabase volume

The following is a suggested workflow for working with netCDF data and Arc Hydro Groundwater Pro:

  1. Use the appropriate tool from the Multidimension Tools toolbox to convert the netCDF data to the desired data form.
  2. If necessary, add it to the Arc Hydro Groundwater Pro geodatabase. This might be essential depending on what you hope to do with the data.
  3. Make any necessary adjustments or additions to the data to ensure compatibility with the Arc Hydro Groundwater Pro tool you hope to use.
  4. Use the feature layer, raster layer, and table view in the Arc Hydro Groundwater Pro tool of your choice.

A similar workflow exists for Arc Hydro Groundwater for ArcGIS Desktop:

  1. Load netCDF data into the map.
  2. Use the appropriate netCDF-related tool from the Multidimension toolbox.
  3. The output of that tool (e.g. a netCDF feature layer) can be used as input to any geoprocessing tool that accepts that kind of input.
  4. If desired, the temporary layer from the Make NetCDF Feature Layer tool can be saved to your computer's drive with the "Save To Layer File" or "Copy Features" tool.

It's possible that the netCDF data does not have the appropriate data for use with Arc Hydro Groundwater Pro. You might have to edit the data to ensure compatibility (e.g. adding HydroIDs). Furthermore, converting netCDF data to a feature layer or a raster does not mean you have all the data needed to run your Arc Hydro Groundwater Pro. Usually, the feature layer, raster layer, or table will just be one piece of running a tool effectively.

Try using netCDF data with Arc Hydro Groundwater Pro today!

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Viewing SRH-2D Simulation Plots

SMS generates multiple plots during the SHR-2D model run. These solution plots include data collected by monitor points or lines as well as information such as mass balance and percentage of flow that enters the simulation. This post will discuss accessing and using the solution plots.

The first way to view the SRH-2D Solution plots is through the simulation data in the Simulation Run Queue. This allows you to look at the quality of the simulation as it is running. In the Simulation Run Queue, the Monitoring data option needs to be turned on. You can then view the plots as they are generated using the tabs below.

After you have run the simulation, you can view the solutions plots. You can access the SRH-2D Solution Plot by doing the following:

  1. Right-clicking on the simulation item and select Tools from the dropdown to open another submenu.
  2. Click on View Simulation Plots to pull up the SRH-2D Solution Plots window.

This will allow you to look at the list of different plots in the Plots section. On the left, there are a few other options such as the legend, and specifying the time range. The show legend option will have a legend appear in the upper right corner of the plot that has been pulled up. This as well as the specifying of the time range allows you to adjust the graph to your desired time range.

Example of the Solution Plots dialog

It is important to note that the plots in the Solution Plot window are not available in the Plot Wizard. You will need access them through the Solution Plots window. With that, it should be noted that pulling up an older SRH-2D project in a current version of SMS may not have the solution plots. This is because of changes in how files are organized. In this case, the solutions plots can be generated by re-running the simulation.

The SRH-2D Solution Plot is one of the many options in SMS to help you see what is happening in your simulation. Try using the SRH-2D Solution Plot in SMS today!

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Working with Inactive Cells in MODFLOW 6

When working with a MODFLOW 6 model in the Groundwater Modeling System (GMS) it can be important to mark specific cells inside a project as inactive to keep it out of the computational domain. Using inactive cells can speed up the performance and accuracy of your model. Incorrectly designating cells as inactive or active can cause inaccuracies in your model or keep it from converging. Here is some guidance for working with inactive cells that will help create a better MODFLOW 6 model.

Modflow 6 model with inaccurate z values

When choosing which cells to mark as inactive in GMS, it is helpful to know how to find information about the cells in the first place, as well as what information MODFLOW 6 is using to calculate the X, Y, Z, and S values of that cell. The display above the graphics window that shows the values of the selected cell is using the cell center for its calculated values. If the inactive cells have a low elevation that is inaccurate for the model, it will drag the Z value for the active cells on the edge down to meet the inactive cell. This happens because the outside active cell has nodes in the Z value that still need something to attach to as there cannot be gaps between the nodes. This will distort the cells in unintended ways and create errors in the model.

MODFLOW 6 uses IBOUND to determine which cells to mark as active and which to mark as inactive. Marking a cell with an IBOUND value of zero will make it inactive.

There are a few ways to inactivate cells in a MODFLOW 6 model. The first is to create a polygon that will separate the active and inactive cells. Select the polygon that contains the cells that are to remain active. Go to the Feature Objects menu and select Activate Cells in Coverage(s). This will automatically make any cells that aren’t selective inactive.

The second way is to select a group of cells with the cell selection tool. Then go to the MODFLOW menu | Advanced | Cell Properties… and change the IBOUND dropdown menu to inactive. This will inactivate only the cells that have been selected in the graphics window.

The cells can also be set as inactive by editing the IBOUND Array directly.The IBOUND dialog can be found by clicking on Global Options under the MODFLOW menu. There is an IBOUND button in this dialog window where the IJK coordinates can be set to zero manually.

Making use of inactive cells can improve you MODFLOW 6 model. Try out MODFLOW 6 in GMS today!

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