Aquaveo & Water Resources Engineering News

In SMS, designing a good 2D hydraulic model from the start gives the best results. A poorly designed model can give bad results, cause model errors, or even keep the model from converging. And while it may seem easy at first to design a good model, there are plenty of potential pitfalls that can come up if you are not careful.

The following tips, broken down into five areas, can help improve any model.

Terrain Data

Pay attention to your terrain data. You can't set up a good model without a good foundation, and terrain data is your foundation. There are four things you will need to spend time getting right:

• Represent hydraulic controls accurately
• Make sure you include channel bathymetry
• Add breaklines where needed
• Finally review the terrain surface for missing features

Mesh Development

Use an appropriate number of elements: size does matter, more is not always better. This is mainly because the time your model takes to render is a significant factor for any project. Element length should generally be equal to or greater than the flow depth, except for limited areas such as piers. When elements are too small, waves can form skewing the model results.

Quadrilatereal elements in meshes are often more stable than when using triangular elements. Once you have set your number of elements and length, confirm that hydraulic controls are represented in the mesh.

Lastly, review your mesh for quality.

Boundary Conditions

When determining the boundaries of your model, you will need to find two things. First look for the most constricted area when determining model limits. Second, find the furthest usable boundary location from the area of interest. A good rule of thumb for rivers: two floodplain widths up and downstream. Note that the width of the mesh should be greater than the maximum flood width.

Lastly, perform sensitivity analysis on boundary conditions.

Material Roughness

Be aware that Manning's n values for 2D model can be lower than 1D models. Be sure to calibrate your model. Essentially check your results to see if they are reasonable.

Model Execution and Review

• Use the largest time step possible that gives you continuity and stability ( i.e. while still achieving a good solution).
• Use monitoring points to verify steady simulation.
• Use monitoring lines to verify continuity.
• Review convergence parameters to confirm conservation of mass.

Following these tips can improve any model that uses a 2D mesh. Try them out in SMS today!

Do you have a project that requires using a large DEM? Digital Elevation Model files are a great source for terrain data in WMS. A lot of projects require using DEMs which makes it important to use the data available.

Using a large DEM file can present some complications in WMS. A large file may cause the program to slow down or have difficulty processing. So it is important to make certain to use a DEM that contains mostly relevant data and doesn’t contain an excess of nonessential information.

But how do you know if the DEM data you are pulling is enough? Is more watershed data always better?

Pulling in more data doesn’t insure better results. Though WMS is able to handle a massive amount of data (which is not a guarantee) the hardware in your computer may not be able to handle it. In general, a DEM twice the size of your watershed is probably sufficient for most models. More than twice your watershed size tends to just bog down the model causing you to face unnecessary wait times.

What should you do if your watershed data is not loading?

If your data is taking a long time to load try adjusting the resolution. After using the Get Data from Map tool, and making your selection in the Data Service Options dialog, you will be able to select your desired resolution in the Zoom dialog. Selecting a lower resolution zoom level should make the DEM easier to work with in WMS.

You could also try breaking up the DEM into multiple DEMs. That way your computer is not overwhelmed by trying to download one huge file all at once. Then while you’re working on your model you can turn on just the DEM(s) you need.

Third party software can be used to break up the DEM or reduce the resolution.

DEMs remain an excellent source for data for projects in WMS. Download WMS today!

Have you ever built a model in GMS that uses multiple conceptual models? Doing this offers a few advantages. However, there are potential pitfalls as well when doing this. We will discuss some of the advantages in using multiple conceptual models and what to watch out for.

A conceptual model may contain one or more map coverages. Each coverage should contain feature objects defining key structures of the groundwater model, such as wells, rivers, or recharge. Everything in the conceptual model can then be mapped over to a grid or MODFLOW model.

Beyond using folders under a single conceptual model, one of the main advantages with using multiple conceptual models is for organization. When wanting to make variations on a model, it is helpful to have one base conceptual model and then multiple variant conceptual models. The entire base conceptual model may be duplicated to provide a starting point for other variations, or individual coverages may be duplicated and dragged to other conceptual models. Duplicating the base conceptual model can be particularly helpful if you already have transport species defined for MODFLOW-related models.

For example, you can use one conceptual model for a base steady-state model, then create another conceptual model for a transient predictive model. With this you can map the base conceptual model to MODFLOW and run that model. After you have the base results, you can duplicate the solution datasets to preserve them, adjust Global Options—such as Stress Periods—if needed, and then map the predictive model to the grid to run your second MODFLOW model.

When using multiple conceptual models, there are few items to look out for. These include:

• When changing the conceptual model, changes are not automatically made to the MODFLOW model or other models being used. The conceptual model must be mapped over to the groundwater model in order for the defined features to be included in the model run.
• When mapping over the conceptual model, it will overwrite any existing data in the same packages contained in the conceptual model. If you want to update the model with the new conceptual model, this is the correct workflow. However, if the original conceptual model used packages that are no longer used in the new conceptual model, then there could be an error in the model run. Always review your model after mapping to confirm the features mapped as you intended.
• When using MODFLOW-USG, and you have multiple UGrids, make certain the conceptual model is mapping to the correct UGrid or model. It will map to the active UGrid.

Working with multiple conceptual models can expand your options for your model. Try out the conceptual model and other features of GMS today!

The 2019 Aquaveo User Conference is going on now. It started yesterday, October 8th, and will wrap up today, October 9th. We are enjoying meeting with users from around the world. In attendance are users from the United States, Germany, Portugal, South Africa, and other places around the globe.

At the conference, we announced some of the new features and upcoming changes to our products that we are excited about:

• Making XMS functionality available for use outside of the traditional interface.
• More web-based applications for portability and ease of access.
• Simplifying and unifying tools so it is easier to find and use the functionalities available.
• Project management tools to track the history of a model.
• 3D bridge modeling in SMS.

Talking to those in attendance, we learned they enjoyed:

• Learning more about software features and functionality.
• Learning how to improve their model development process.
• Discovering benefits of Aquaveo’s software over other software.
• Talking to developers and learning tips for model development.
• Being able to show off their models and receive feedback on them.

We’d like the thank the following for participating during our user conference:

• Scott Hogan with the Federal Highway Administration
• Scott Kudlas with the Office of Water Supply, Virginia Dept. of Environmental Quality
• Eva Loch with Hydrotec
R. Jeffrey Davis with Barr Engineering
• Andrea Borgia with the Lawrence Berkeley National Laboratory
• Yazmin Avila with the City of Austin Watershed Protection Division
• Young-Hoon Jin with the City of Austin Watershed Protection Division
• Antonio Trigo-Teixeira with the Instituto Superior Tecnico, University of Lisbon
• Rute Ramos from the Laboratorio Nacional de Engenharia Civil
• Eric Miller with GeoEngineers
• Mitch Brown with the Coastal and Hydraulics Laboratory, U.S. Army Corps. Of Engineers
• Chris Massey with the U.S. Army Corps of Engineers

If you couldn’t make it to the Aquaveo User Conference this year, watch our website and Facebook page for future conferences.