Aquaveo & Water Resources Engineering News

Build Watershed and Streams from Raster Data

By aquaveo on August 27, 2024

Delineating a watershed area into a usable model can be a daunting process. Two new tools in the Surface-water Modeling System (SMS) Toolbox make defining a watershed domain quick and easy. Introducing the Streams from Rasters and the Watershed from Rasters tools.

These two tools are found in the Coverages folder in the Toolbox.These two tools can extract data from an imported raster to automatically generate the feature objects for watershed streams and domains for your SMS model.

The first tool, Streams from Raster, will evaluate the raster elevation data, extract the direction of runoff, create connected arcs, and put it into a separate coverage for you. You’ll need a directional raster in order to run the tool.

The Streams from Raster tool will show the entire runoff flow based on elevation in the selected raster. If water starts here, then it will go in that direction until it ends up there in that stream bed. You can see and trace the most likely paths for water flow until it hits the lowest point possible for that flow path. This can help you plan where to place your stream arcs for your model.

A watershed domain created from raster data

The Watershed from Rasters tool creates a domain of the watershed area. This tool uses an amalgamation of several processes that operate in a particular order in the background as the tool runs. Several of these processes have been added to the Toolbox, including Streams from Raster, to run as separate tools, if desired. Once run, you will end up adding feature objects that define a domain to a coverage.

Then, the feature objects can be used to create a geometry (2D or 3D meshes or UGrids, etc.) of the watershed area. By using the Watershed from Raster tool, it enhances the speed at which a model can be created.

Head on over to SMS and try delineating a watershed with these new tools in your next model.

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SMS

Utilizing Contour Legends

By aquaveo on August 20, 2024

The Groundwater Modeling System (GMS) contains many tools for visualizing data. The contour visualization tools are particularly helpful in viewing solution data. With contours, GMS provides several options for how contours will be displayed, including options for the contour legend. When a legend is added to the contour display, it is not always clear what the units of the values shown in the legend are. With GMS 10.8 improvement to the Contour Legend Options allow displaying the data units with the legend.

The Contour Legend Options dialog is available for the contour dataset displayed in the Graphics Window. Accessed from the Legend Options button on the Contour Options dialog, the Contour Legend Options dialog controls the formatting and location of a displayed legend. The tool is only available if the Legend check box on the Contour Display Options Dialog is checked. This dialog includes formatting options such as a title field, a font selection button, as well as fields for height and width. Furthermore, the dialog offers location options that includes a combo box for specifying the location of the displayed legend. Visit our wiki page to view descriptions of each feature this dialog provides.

Here is a step-by-step of how to execute this feature:

  1. Select Contour Options.
  2. At the bottom of the Dataset Contour Options dialog, ensure that the Legend option is checked.
  3. Select Options in the Legend section.
  4. In the Formatting Section of the Contour Legend Options dialog, enter the respective unit keyword: "UNITS" for DS (Datasets) and "TUNITS" for (Time steps).
Contour legend options in GMS

The ability to add the unit type to the legend is a user requested feature that helps make presenting data clearer for your audience. This and other improvements are continuously being added to GMS. Head over to GMS and check out the options for legend displays and other features.

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GMS

Tips for Manually Editing Stream Arcs

By aquaveo on August 13, 2024

Did you generate stream arcs in your Watershed Modeling System (WMS) model that you discovered later needed to be adjusted? Or maybe the outlet point’s position needs to be slightly adjusted. You can manually edit streams without using any of the wizards available in WMS, but you do need to be careful. Here are some tips on how to do it and what to watch for.

To manually edit your stream arcs, you will need to use the tools in the Map module. You can select and move a stream node or vertex to alter the path of a stream. You can also change a node to a vertex, create new feature points where needed, and manually edit properties in the Properties screen. You may wish to change your Display Options so that you can see the stream arcs, and vertices more clearly. Used carefully, you can make minor adjustments without using the wizards.

If you need to shift a stream outlet point or other major node, you can use the Select Feature Point/Node tool to select the stream outlet point and drag it to a new position. When the stream outlet point is originally on an arc but then moved away from the arc, the arc can snap to the new outlet location. Be careful where you move your stream outlet point, (or any stream arc vertex), especially if you accidentally shift it to a higher elevation, as this can create digital dams or break the model.

Streams in WMS

If you have extremely long stream arcs, or need to make precise corrections around obstacles, land formations, or buildings, you can manually add one or more vertices to the arc using the Create Feature Vertex tool. Then, you can then use the Select Feature Vertex tool to select and move them to better locations within the bounds of the model. This can be especially useful if you discover that one or more of your steam arcs now cross outside the bounds of the delineation arcs after manually editing them.

If you’ve changed a stream arc by adding vertices or just moving locations, you’ve also changed the vertex distribution along the arc. It may be necessary to redistribute the vertices again.

You will want to check elevation values against the DEM. If you have moved a stream arc point, you may have shifted it from its elevation. You may need to re-interpolate elevations back onto the stream arcs.

It is also recommended that manual edits be done prior to defining the model, otherwise you may discover that making these edits, while improving the stream arcs, has broken the model. If that happens, you may need to re-delineate the watershed. You can go back to the wizard that you used to delineate your watershed model and skip to the appropriate step to rework your model from there.

This manual editing of stream arcs is different from the GSSHA’s Smooth Stream/Pipe Arcs tool and works outside of any wizards within WMS.

Try out any of the tips with your watershed projects in WMS today!

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WMS

2D Mesh Editing Versus Regeneration: Which is More Apt?

By aquaveo on August 6, 2024

If you need to make a change to a mesh, should you use the toold in the 2D Mesh module to edit, or instead regenerate the mesh? A 2D mesh consists of elements that define the computational domain of the numerical model. A numerical simulation requires a geometric definition of its domain– the mesh, available for use in SMS 13.3. Occasionally when constructing a mesh, a moment occurs where the mesh is insufficient for any reason.

In most cases the recommendation is to regenerate the mesh; as opposed to editing the mesh manually. The following list involves common circumstances where one may manually edit a mesh:

  • There is no mesh generator coverage present.
  • Deleting Outer Elements: Since the triangulation process creates elements (i.e. thin triangles) outside the mesh boundaries, deleting outer elements provides some refinement.
  • Merging Triangles/Element: Numeric solvers are more stable and accurate when quadrilateral elements are rectangular and triangular elements are equilateral.
  • Editing Individual Elements: After compound edits, a mesh could benefit from individual manipulation to increase stability. Swapping edges: Think of the two triangles as a quadrilateral, and the common edge between them is a diagonal of the quadrilateral. By swapping this common edge, it changes to be along the opposite diagonal of the quadrilateral. If this edge is clicked again, it returns back to its original state.
  • Turning a specific element into a void element.

You may make edits in the Mesh Generator coverage. Manual edits should be intentional and reserved for small sections of a mesh. Generally, manual edits of a mesh ought to be minimal.

In nearly all cases the recommendation is to regenerate the mesh; as opposed to editing the mesh manually. This is because any process that edits a mesh, causes the node and element ordering to become disorganized. Additionally, editing a mesh invalidates any solution files that have been previously saved. Manually editing a 2D mesh risks creating issues with the assigned elevation data or other datasets being used. As such, if there is a solution dataset attached to the mesh, the model simulation should be re-run.

Example of file generated mesh preview

A useful tip is reviewing your mesh before generating, using the preview tools that are available in a given dialog. Make adjustments to the arcs, vertices, and polygons on the mesh. Do not be afraid to add more arcs, vertices, or polygons if further refinement is needed.

If you want to generate a new mesh with the desired edits, you will need to create a mesh generator coverage. The following are examples of tools that can create a new mesh:

  • Map → 2D Mesh tool.
  • 2D Mesh from 2D Grid in the toolbox.
  • Additionally, most of the Unstructured Grid tools may be utilized to generate a new mesh.

Make use of the mesh editing and generating capabilities of SMS 13.3 today!

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SMS