Tips for Modeling 3D Bridges in SMS 13.2

Do you have an SMS 13.2 project that could benefit from using a 3D bridge? Today's blog post covers some things to consider as you model 3D bridges in SMS.

First, it’s important to know that SMS identifies the arc drawn first as the upstream side of the bridge. So the order in which the arcs are drawn affects the final bridge model. However, before the bridge is fully created, it’s possible to switch which side of the bridge is upstream using the Swap Arcs command in the Bridge dialog. Checking that the arcs are assigned to the correct side of the bridge can prevent errors later in the model.

When the bridge is created, it can be imported automatically into the model. So the bridge file is exported from SMS, but then SMS imports it automatically. To import the bridge automatically, select the Add 3D Bridge UGrid to SMS on OK option in the Bridge dialog. This eliminates the need to search for it then import it.

Example of 3D Bridge Modeling in SMS

However, if the 3D bridge file is moved, it's important to keep in mind that two files were created by modeling the bridge: an XMUGRID file and a PRJ file that contains the projection for the UGrid. These files should be kept together.

Finally, modeling piers is sometimes an important part of modeling a 3D bridge. The top and underside of a 3D bridge are defined using XY Series Editors accessible in the Bridge dialog. When defining any elevation changes in the 3D bridge, the distance (x) values cannot be identical to each other. This means it’s impossible to create a precisely vertical slope using this tool. To approximate a vertical slope, first input distance values that are very close to each other (e.g. 79 and 80). Then, pair them with elevation values that reflect the change in elevation.

Please keep in mind that piers used for an SRH-2D pressure flow model should not be modeled using the 3D bridge tool. Piers in that kind of model should be modeled using voids in the mesh.

Use these tips in creating a 3D bridge in SMS 13.2 today!

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How to Export Contour Lines as Shapefiles in SMS

Have you been wanting to export the contour lines in your SMS project as a shapefile so they can be opened in a different application? SMS allows exporting contour lines as a shapefile. This post will explain how to export contour lines as shapefiles.

Saving your contours as a shapefile requires your project to be set up correctly. Save the contours as a shapefile by doing the following:

  1. Make sure the contours you want to convert to a shapefile are set to Linear in the Display Options. To do so, open Display Options and click on the page for the geometry that has the contoured dataset loaded (e.g. mesh, UGrid, etc.). First, make sure that contours are turned on. Then, click on the Contours tab. In the Contour Method in the top left, make certain the first dropdown is set to "Linear".
  2. Make sure the desired dataset is active in SMS. This can be done by clicking on the dataset in the Project Explorer.
  3. In the File menu, select the Save As command. In the Save as type drop-down menu, select Shapes Files (*.shp). Then navigate to the desired directory. Make sure it's somewhere you will know how to find it. Then click Save.
  4. Once you’ve clicked Save, a dialog opens that gives you options for converting project information to a shapefile. Select one of the contour options. The “Mesh Contours → Arc Shapefile” option is usually best.
  5. Now open your shapefile in the appropriate GIS software. The contour lines will appear as arc lines.
Example of Exporting a Shapefile from SMS

If you encounter issues with the shapefile, start by checking the folder where you saved the file. Make certain that all of the necessary files for the shapefile are there, including a projection file.

Another item to check is that everything you want in the shapefile is displayed correctly in the Graphics Window before you export. Try using the Uncheck All command in the Project Explorer and then checking only the desired geometry. This could allow you to more clearly see the contours as they will appear in the shapefile. You might also consider using the display options to turn off the geometry elements. This would also allow for clearer visualization of the contours. Once you can see the contour lines clearly, use the display options to adjust the contour lines if needed. Finally, there may be some differences between how SMS displays a shapefile and how other GIS applications display the shapefile. Opening the shapefile in SMS can help you determine if this is the case.

Be aware that selecting the Mesh Contours → Polygon Shapefile option when exporting the shapefile causes SMS to create a shapefile with only polygons. This might not accurately reflect the linear contours displayed in SMS since some of them might be only line segments.

Try out exporting contour lines as shapefiles in SMS today!

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Specifying Arc Lengths in SMS 13.2

Imagine yourself trying to get an arc in an SMS map coverage just the right length. You keep on moving around the endpoint, but that often moves its azimuth as well. What’s more, measuring the arc would require using the Measure tool, and maybe that’s not precise enough for you. Fortunately, the most recent release of SMS has a solution. Today, we take a closer look at the Specify Arc Length tool, a tool designed for helping you be detailed in creating arcs. This tool, which was released as part of the beta of SMS 13.2, enables you to extend or shorten an arc by a specified length.

Let’s say that you have drawn an arc, and it’s pretty close to what you wanted, but you would prefer it just a little longer. You could manually adjust it, but using the Specify Arc Length tool, you can make it exactly the length you prefer.

Here’s how:

  1. In the Map module, select the Select Feature Arc tool.
  2. Select the arc you want to modify.
  3. Right-click and select the Specify Arc Length command.
  4. In the Specify Arc Length dialog, specify the desired arc length in the New Arc Length section.
Example of the Specify Arc Length in SMS

If the desired arc length is longer than arc’s current length, then the arc extends to match the entered length. If the desired arc length is shorter than the arc’s current length, then a new node is created to shorten the arc. Shortening an arc results in the creation of two arcs.

There are some important things to keep in mind when using this new tool.

First, the arc can only be adjusted relative to the arc direction, which is usually the direction the arc was drawn (e.g. right to left) when it was created. This means extending the arc moves the end node of the arc in a straight line in the arc direction until the whole arc is the desired length. Shortening the arc adds a node the specified distance along the arc in the arc direction. This can be seen in the image below. The beginning of the arc (usually the node drawn first) never moves as a result of the Specify Arc Length tool.

It’s also important to be aware of the arcs attached to the arc you’re modifying. If the arc is attached to another arc, then extending the arc also modifies the length of the arc it is attached to. Be sure that adjusting both arc lengths is desirable before using this tool.

Furthermore, when extending an arc with many segments, note that only the segment at the end of the arc gets extended. The final segment extends in a straight line as shown below until the arc is the specified length. The rest of the segments are left untouched.

This is just one of the many tools that SMS13.2 makes available to enhance your water modeling capabilities. Try out using the Specify Arc Length tool in SMS 13.2 today.

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Rebuilding an SRH-2D Restart File

Have you ever needed to rebuild an SRH-2D restart file for a project you were working on? Perhaps you lost the restart file or maybe you made modifications to your mesh, so the restart file is no longer valid for the model you have. Regardless of the cause, rebuilding a restart file can be a vital step in completing the model you're working on.

To start rebuilding your restart file, see if you can do a dry run of your simulation:

Example of the SRH-2D Model Control Set to Use a Dry Run
  1. Right-click on the simulation in the Project Explorer and select Duplicate.
  2. This ensures that the original simulation is preserved if needed.
  3. In the newly-created simulation, right-click and select Model Control to open the Model Control dialog.
  4. In the dialog on the General tab, for the Initial Condition drop-down select "Dry".

Every run of SRH-2D creates restart files for the model. Initially, it creates a restart file for every time step as determined by the Output Frequency in the Model Control dialog. However, when the solution is loaded into SMS, the software only saves the restart file for the final time step. If a restart file for a different time step in the simulation is desired, then please complete the following before clicking Load Solution in the Simulation Run Queue dialog:

  1. Browse to where the project is saved.
  2. Double-click on the folder with the same name as the SMS project.
  3. Double-click on the SRH-2D folder.
  4. Double-click on the folder with the same name as the simulation run.
  5. This is where restart files were written for every time step. The file that ends in "_TSO.dat" is a text file with information about which restart files correspond to each time step. Open it in a program that can read plain text files to make sure that you select the restart file with the desired time step. The restart files end in "_RST" followed by the time step number (e.g. "Standard_Run_RST12.dat").
  6. Once you have determined the restart file you want to save, copy and paste it in a different folder on your hard drive.
  7. Then click Load Solution in SMS.

SMS loads the results into SMS and keeps only the restart file for the final time step. It's important to remember that changing anything in the mesh necessitates the creation of a new restart file. Restart files should only be used with a model that uses the exact same mesh as the simulation that generated the restart file. Using the restart file with a slightly modified mesh might yield inaccurate results.

SRH-2 with SMS provides powerful tools for surface-water modeling. Use SMS today!

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