Aquaveo & Water Resources Engineering News

Using Advanced Data Services Options

In the current versions of GMS, SMS, and WMS, the data service options for importing online maps has changed. It was noted by some of our users that the Advanced option for the Data Services Options dialog was removed.

We are happy to say that the advanced options for the Data Services Options dialog has been restored. The new advanced options are only available when using the Import from Web command in the release of GMS, SMS, and WMS that went out at the beginning of May 2019.

To access the Advanced options from the Data Services Options dialog, click the Advanced button, just as before, to bring up the Select Online Source dialog. This dialog allows users to bring in new data sources for downloading data.

Select Online Source Dialog

Adding new data sources to the Select Online Source dialog can be done in any of three ways:

    Add New Source Dialog
  1. The Select Online Source dialog contains a list of all of the data sources currently available. You can select one of these sources and click the Duplicate Source button to create a copy of the data source. Then, with the copy selected, click the Edit Source button to reach a dialog where you can make modifications to the source such as limiting the layers downloaded from the source or changing the image format downloaded from the source.
  2. You can click the Add New Source button to reach a dialog where you can specify the url of a new data source along with any modifications.
  3. Finally, if you have an Online Source File with the information needed to reach a source, you can click the Add Sources from File to add the source to the available list.

Sources can be deleted from the available list by selecting a source in the list and clicking the Remove Source button. Only sources that have been manually added can be removed or edited.

To get access to the new advanced options for the Data Services Options dialog, visit our downloads page today.

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What Makes a Good Quality Mesh?

Several models in SMS rely on using a 2D mesh. The quality of this mesh can greatly impact your model run and overall results, so here are some tips for making a good quality mesh.

Start with a Good Mesh Generator Coverage

A lot of how well a mesh turns out begins with the mesh generator coverage. Generally, when a poor mesh has been generated, it is because the arcs, vertices, and polygons on the mesh generator coverage did not clearly define a good quality mesh.

When defining the mesh parameters in the coverage, there are few items to keep in mind:

  • Make certain the polygons accurately reflect the work area. Do not draw polygons outside of your elevation data.
  • Vertices along the arcs determines the size and spacing of elements in the mesh. Adding too few or too many vertices along an arc can cause poor spacing. Using the Redistribute Vertices tool can help with getting the correct number of vertices, and making sure they are evenly spaced along each arc.
  • Keep individual arcs smooth and rounded to avoid interior acute angles.
  • Use the 2D Mesh Polygon Properties dialog to preview how the final mesh will appear.
Mesh generation coverage example
Check the Size Transition of the Elements

How elements transition in size can greatly impact how a model uses the mesh. In general, a gradual change in element size functions makes for a better mesh for most models. A poor mesh will have a quick change in elements size, acute interior angles, and thin triangles.

Mesh with incorrect spacing

The solution for smoothing out the element transition is to adjust the spacing of the arc vertices in the mesh generator coverage and to examine the proximity of the arcs. In general, arcs that are close to each other should have a similar number of vertices. Arcs that are further apart can have a greater disparity of vertices.

Mesh with corrected spacing
Check For an Even Patch

When creating quadrilateral elements in a mesh using a patch, it is important that the spacing of the vertices be precise. Parallel arcs need to have the same number of vertices when creating a patch or the result will be an uneven patch.

Example of an uneven patch

It is recommended to always preview the mesh when using the patch option, then adjust the number of vertices to make certain the patch is even.

Remove Unnecessary Elements

Cleaning up a mesh after it has been generated is sometimes necessary. When generating a mesh from a scatter set or other source, more of the mesh may need to be reviewed and cleaned. Using the Select Thin Triangles command and the Clean command can help with getting rid of unnecessary elements that could cause problems during the model run. It is also recommended to use a mesh with the fewest number of elements needed for your project.

These are only some of the recommended guidelines for generating a good quality mesh. We hope this helps you in your projects.

If you have questions about how to make a better mesh in SMS, contact our technical support for general questions, or contact our consulting services for project-specific inquiries.

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Splitting UGrid Layers

Have you been working with a project in GMS only to discover that the project’s 3D unstructured grid (UGrid) needs to include another layer? Fortunately, it’s rare that a UGrid needs to have another layer, but every once in a while a layer needs to be added to an existing UGrid. GMS provides a way to divide UGrid layers quickly.

One thing to note: whenever a UGrid is changed—such as with adding a new layer—the existing MODFLOW simulation attached to the UGrid will be removed. It is therefore best to make certain the UGrid is correct—including having the necessary number of layers—before building the MODFLOW simulation.

In order to add a new layer to an existing Ugrid, do the following:

  1. Using the Select Cell tool, select a cell on the layer you want to split.
  2. Right-click on the selected cell and select the Split Layer command to start the process of dividing the UGrid layer.
UGrid layer before and after being split

When GMS finishes processing, it creates a new UGrid with the additional layer, leaving the original UGrid intact. The layer to which the selected cell belonged is divided into two layers on the new UGrid. GMS averages the distance between the top and bottom of the layer, then divides the layer equally to create the two new layers. It is recommended to carefully review the new UGrid to check for any unintended anomalies.

As mentioned above, any MODFLOW simulations contained in the original UGrid are not copied to the new UGrid. A new MODFLOW simulation must be created for the new UGrid.

Another option is to create a new UGrid with the additional layer and leave the existing UGrid as is. This option is best if you need to finely control the layer elevations.

For adding layers to complicated UGrids, you may want to consider using Aquaveo’s consulting services.

Now that you’ve seen the basics of splitting a UGrid layer, try it out in GMS today!

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Modeling a Dam in GSSHA

Do you have a project that requires modeling a dam, or similar structure, in GSSHA? WMS can make this process smoother with tools designed to help define the structure quickly and efficiently.

In order to create a simulation that includes modeling the dam in WMS and analyzing the dam’s effects using GSSHA, the workflow is as follows:

  1. Import an existing GSSHA base model.
  2. In the GSSHA map coverage, use the Shift key to select the node where you want the dam to be and the node immediately downstream from it.
  3. Right-click on the selected nodes and select Attributes to open a Properties dialog.
  4. Select Output Hydrographs at those nodes.
  5. Run GSSHA.
  6. Using the results from the GSSHA run, size your embankment based on the necessary storage.
  7. Using the Create Feature Arc tool, create an arc to represent your dam.
  8. Double-click on the arc to bring up the Attributes dialog.
  9. Set the type of arc to be an Embankment, then click the ... button next to it to open the Embankment Arc Profile Editor dialog.
    1. Set the PVI Elevation to be the height of the dam.
    2. Click Compute Vertical Curve to compute the Curve Length.
  10. Double-click the node in the stream where your structures will be defined to open the Properties dialog.
  11. Click the button under Hydraulic structures to open the GSSHA Hydraulic Structures dialog.
    1. Add a Detention Basin, Weir and Culvert.
    2. Define the attributes for each of these structures.
  12. Run GSSHA again to see the effects of the dam you have created.
GSSHA Dam Modeled in WMS

If needed, adjust the display options when reviewing the results to get a better idea of how the dam structure affected the results. Try different various options to get a better feel of how the dam affected the simulation results.

Now that you know how to add a dam to GSSHA, try out modeling dam structures and other applications in WMS today!
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