SMS

Using Internal Sinks and Links in SRH-2D

By aquaveo on July 17, 2019

Do you have an SRH-2D project that requires placing a drain inside the mesh? Or perhaps you have two seperate meshes in your project where you need to have water flowing between them? Both of these scenarios can be resolved by respectively using the internal sink and link boundary conditions.

Internal Sink Boundary Condition

The internal sink boundary condition is assigned to an arc on an SRH-2D boundary condition map coverage. Unlike an inflow or outflow boundary condition, an internal sink is assigned to an arc that is inside the mesh boundaries.

An internal sink can simulate wells, drains or other points of outflow. It can also simulate a source by specifying a negative number for the flow.

It should be noted that an internal sink boundary condition should not be used as a model’s primary source of inflow or outflow. Inflow and outflow boundary conditions should be placed on the mesh boundary.

Links

Link boundary conditions can be used to simulate moving water between two different meshes or two different areas of the same mesh. Links can sometimes be used to make a simple representation of a pipe or similar structure connecting two areas.

Links are made by making two arcs on an SRH-2D boundary condition coverage. Both arcs are selected when assigning the Link property type. One arc should be assigned as the link inflow boundary condition and the other arcs should be assigned as the link outflow.

It should be noted that link boundary conditions should not be used to model culverts or other such structures. Also, link boundary conditions should not be used as the primary inflow or outflow source for a project.

Now that you know a little more about using internal sink and link boundary conditions, try using them in your SRH-2D projects in SMS.

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Using the Plot Data Coverage

By aquaveo on June 5, 2019

Have you generated a plot in SMS and found it was difficult to see where a bridge, culvert, or other structure location matched up with the plot? The Plot Data coverage helps make them more visible, making an observation coverage more meaningful in a profile plot.

Typically, a profile shows some desired value such as water surface elevation or the riverbed elevation. This data can be more useful in many cases if structures are displayed on the plot as well. A Plot Data coverage allows creating polygons over structures that then helps display the location of the structure on the plot profile.

To use the Plot Data coverage, do the following:

In the Map Module, create a new coverage with the Plot Data type.
In this new Plot Data coverage, create a polygon over the area of interest.
Double-click on the Polygon to assign attributes in the Plot Data dialog.
Create an observation arc that includes the area of interest.
Create an observation profile plot.
In the Plot Data Options, turn on the Plot Data coverage.

The profile plot will now show where the polygon on the Plot Data coverage aligns with the profile.

For example, if you want to consider the impact of a new bridge placement on the flow of a river, you could create a polygon representing the bridge location. When included in the profile, this could help you visualize placing a bridge at that location along the river and at the indicated height. If water elevation data is available, such as from an SRH 2D simulation, the height of the bridge can be easily compared with elevation profile of the water surface. This could be helpful in considering if the bridge would be washed out or flooded during periods of heavy rain when the river swells.

Culverts can similarly be shown on the profile by using the Plot Data coverage. Likewise, obstructions or structures of any shape could also be shown in the profile using the Plot Data coverage. Multiple plot data coverages could be used when there is a desire to layer structures such as a hypothetical bridge and the supporting abutments or columns.

Try out using the Plot Data coverage in SMS today!

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SMS

Using Advanced Data Services Options

By aquaveo on May 22, 2019

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.

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

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.
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.
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?

By aquaveo on May 15, 2019

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.

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.

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.

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.

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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