SMS

Creating SRH-2D Pressure Zones with Overtopping

By aquaveo on September 12, 2018

Do you have a location in your SRH-2D project for a box culvert or pressure zone with overtopping?

It is a common feature added to many SRH-2D models. Depending on how the pressure zone is created in SMS, this can be a tricky process for SRH-2D to handle. Here are some steps and tips for creating this feature successfully in SMS.

1 Use Quadrilateral Elements

Create quadrilateral elements between the boundaries of the pressure zone. Using quadrilateral elements tends to increase the stability and reliability of the SRH-2D model run. Quadrilateral elements can be created in one of two ways.

The first is to create the quadrilateral elements when creating the 2D mesh. Create a polygon for the area between and around the pressure zone. Assign this polygon with the Patch mesh type in the 2D Mesh Polygon Properties dialog.

The second method is to create the quadrilateral elements directly in the mesh using the Split/Merge tool and the Switch Element tool. This can be time-consuming, so it is only recommended for small adjustments.

2 Create Voids

Create voids in the mesh on either side of the pressure zone. There are two options for creating these voids, but one option seems to work better.

The first option, and the more stable one, is to create the voids on either side of the pressure zone when generating the mesh. Create the voids as polygons and assign them the None mesh type.

The second option is to generate the mesh then use the Select Elements tool to select and delete the elements where the voids should be. Using this method requires renumbering the mesh nodes. There is a risk that you will not be able to delete all of the nodes related to the elements which can make your mesh unusable to SRH-2D.

3 Assign Boundary Conditions

Two arcs are needed to define the pressure zone. Each arc should be created on an SRH-2D boundary condition coverage. When creating the arcs, make certain all 2D mesh elements between the arcs are quadrilateral elements. Also, it is advisable to have at least one row of quadrilateral elements just past the downstream arc.

Once the arcs have been drawn, select both arcs and open the SRH-2D Linear BC dialog. Set both arcs to the Pressure type and turn on the Overtopping option.

Both the boundary condition coverage and the 2D mesh can be added to your SRH-2D simulation to have a pressure zone with overtopping included in the results.

Try out adding a pressure zone in the community edition of SMS today!

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Converting Units

By aquaveo on August 22, 2018

Seeing which units are being used in a project or for a particular object within the project is fairly easy. Converting the units from, for example, U.S. feet to meters, can introduce problems into a project if you do not do it in the correct way.

Reproject

Reprojecting the data involves moving the data from one coordinate system to another. So if your data is in a UTM coordinate system in meters and the rest of your project is in a State Plane projection that uses U.S. survey feet, reprojecting can change the data to match. Conceptually, the data will remain in the same location, but the data will be adjusted to the new units.

To reproject a dataset:

  1. Right-click on the dataset in the Project Explorer and select Reproject.
  2. In the Reproject dialog, the current projection is shown on the left. On the right side, set the new projection and units.

When converting units through reprojection, keep in mind that Z values (elevations) don’t always convert correctly. Round off errors sometimes occur when reprojecting data. In general, reproject does well in changing the X and Y units. The Z value, if it has been set as the bathymetry, typically also converts units well using the reproject option. Other datasets often do not convert between units using the reproject method.

When converting from rasters to scatter sets, the elevation is usually recognized and converted correctly.

Dataset Calculator

Datasets units can be converted using the Dataset Calculator. This is often necessary when the data has been reprojected, but not all of the datasets can be converted using that method. For example, a velocity dataset or conductivity data.

To convert a dataset with the Dataset Calculator:

  1. Select the desired dataset in the Project Explorer.
  2. Select the Data Calculator macro, or the Data Calculator command or the Dataset Toolbox command in the Data menu.
  3. Select the dataset to convert, then multiple or divide the dataset by the conversion value.

There are a few numbers it is useful to have when doing these conversions:

  • 0.304800609601 meters is equal to one U.S. Survey foot
  • 3.28083333333 U.S. Survey feet are equal to one meter
  • 0.3048 meters is equal to one International foot
  • 3.28083989501 International feet are equal to one meter

Note that there are many datasets that will not work with the Data Calculator.

In the end, make certain all the data being used in your model is in the correct units. Having mismatched units will typically create model errors and generate inaccurate results.

Try reprojecting data or using the Data Calculator to convert units in GMS, SMS, or WMS today!
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WMS

Converting an RMA2 Project to SRH-2D

By aquaveo on August 15, 2018

Do you have an older RMA2 or FESWMS project that you want to convert to an SRH-2D project in SMS? Older model lack the support and many of the features of newer models. In some cases, older models will no longer run with newer operating systems. So converting older projects over helps ensure the accuracy and stability of your results.

Converting projects from an older model is not automatic. Typically, portions of the model will need to be rebuilt. Here is an example of how to convert an older RMA2 model to an SRH-2D model.

Start with creating the SRH-2D mesh.

  1. Load the RMA2 project into the current version of SMS.
  2. Right-click on the RMA2 mesh, and select Duplicate. The duplicated mesh will be used for SRH-2D. The existing RMA2 mesh will be needed, so do not delete it.
  3. Select the duplicated mesh to make it active.
  4. Select the Data | Switch Current Model menu command.
  5. In the Select Current Model dialog, select the Generic Mesh option. The is the mesh type that SRH-2D supports. Be careful to not confuse the Generic Mesh option with the Generic Model option.
  6. Click Yes when warned that there may be data loss.
  7. Click Yes when warned that you are changing from a quadratic mesh to a linear mesh.

Next, you’ll need to define the boundary conditions.

  1. Select the RMA2 mesh to make it active.
  2. Select the Data | Mesh → Map menu command.
  3. In the Mesh → Map dialog, select the Nodestrings → Arc options.
  4. Select the Create New Coverage button.
  5. In the New Coverage dialog, select SRH-2D Boundary Conditions for the Coverage Type.
  6. When done, a new coverage will appear in the Project Explorer with feature arcs in the location of the nodestrings from the RMA2 project.
  7. Select each feature arc in turn and set boundary condition parameters that approximate those in the RMA2 model. Review the RMA2 boundary conditions if needed. Additional boundary conditions can also be added if desired.

You need to define the materials next.

  1. Select the RMA2 mesh to make it active.
  2. Select the Data | Mesh → Map menu command.
  3. In the Mesh → Map dialog, select the Material Regions → Polygons options.
  4. Select the Create New Coverage button.
  5. In the New Coverage dialog, select SRH-2D Materials for the Coverage Type.
  6. When done, a new coverage will appear the Project Explorer with polygons on the assigned materials in the RMA2 project.
  7. Review the material properties and the assigned materials for each polygon to make certain they converted correctly.

Finally, build the SRH-2D model simulation.

  1. Right-click in an empty space in the Project Explorer and select New Simulation | SRH-2D
  2. Link the SRH-2D mesh, boundary condition coverage, and material coverage to the new simulation.
  3. Right-click on the new simulation and select Model Control.
  4. Set the SRH-2D model control to approximate the conditions in the RMA2 model. Review the RMA2 model control if needed.

At this point, the RMA2 mesh could be removed and the SRH-2D model should be ready to run, though some tweaking may be necessary. Refer to the SRH-2D Troubleshooting Guide if needed.

Converting other models, such as FESWMS, follow a similar process to that described above. Try out this conversion process with your older projects today in SMS.

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5 Ways to Make Projects Work Faster

By aquaveo on July 25, 2018

Have you ever noticed your SMS project taking a long time to open or running slow when you’re working in it? Does the project seem to lag when zooming or panning? Perhaps it is time to clean up your project so it runs faster.

While not every project can be made to load or work faster, there are some items that can be done to speed things up. In general, a project that takes a long time to open or operates slowly is usually a larger project with many large components. Having a detailed mesh or large raster files will often slow down SMS on many machines.

To get things going faster, here are five tips for making your project work faster.

1. Change Display Options

Having more objects visible in the Graphics Window will impact how quickly SMS can operate. When SMS is trying to display a lot of data, it will slow down. By reducing the amount of visual information in the Graphics Window, SMS can process faster. This can be done in two ways.

The first method is to hide items in the Project Explorer, such as images or map coverages that are not being currently used. Having several images and rasters showing can particularly slow down a project.

The second method is to open the Display Options dialog and turn off options that are not needed. Contours and vector displays and displaying mesh elements can particularly slow down SMS. Keeping the total number of active display options to a minimum when working with large projects can speed things up for you.

Finally, when opening a large project or file, turning off all or nearly all of the display options can reduce the time it takes to open.

2. Remove Unnecessary Files

Does your project have a lot of data in it? There is a chance that this is slowing things down. Removing files that are no longer needed from the project can help.

If you have already interpolated your elevation data to your mesh or grid, then that data can be removed. If you have a dynamic image in your project, SMS will update the image every time you zoom or pan. Replacing the dynamic image with a static image and removing the dynamic image will speed things up. Shapefiles can also be removed from the project once you’ve interpolated or converted their data.

3. Resample Rasters

Having a large raster or lidar file is not really that unusual. However, having a 10 gigabyte (or larger) file loaded into your project will make SMS run slower. In many cases, all of the data contained in these large files isn’t necessary for the model to run and obtain accurate results.

Resampling the raster to a lower resolution can help. If the raster has already been loaded into SMS, right-click on the raster in the Project Explorer and select Export to resample it. When done resampling and adding the resampled image, remember to remove the original file from the project.

SMS uses a simple resample process. For more controlled application of rasters, other software can be used.

4. Refine the Mesh or Grid

Are you working with a detailed mesh or grid with a lot of elements? While fine detailed meshes and grids are sometimes needed, only certain parts of the mesh or grid may need those details. The rest of the mesh or grid can have larger elements without affecting the accuracy of the project.

For example, when using a mesh for a riverine model, fine elements are generally only needed around the channel and structures. The mesh will often still be suitable using larger elements further away from these key areas.

5. Keep the Number of Simulations Small

Having a lot of simulations in one project file is tempting. For models that use the simulation process, such as SRH-2D, there is no limit to the number you can create.

However, for each simulation in your project file, SMS has to load that instance of the simulation. While all of your simulations may use the same geometry, items such as the model parameters will have been duplicated and increase the file size.

Therefore, when possible, it is best to limit the number of simulations in the project. You may want to create copies of your project then only include simulations in each project that share a particular variable. For example, one project file might have simulations with 10 year predictions while another project file has simulations with 100 year predictions.

Try out any of these tips with your SMS projects today!

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