Aquaveo & Water Resources Engineering News

While working with meshes in the Surface-water Modeling System (SMS), you may have noticed that the more elements there are in the mesh, the slower the processing speed gets when making edits. Subset edit mode allows you to edit just one portion of the mesh at a time, which can increase the processing speed considerably. You can access the “Edit Subset” option by selecting the elements on the mesh you want to work with and right-clicking in the Graphics Window.

Working within the edit subset mode was designed to let you work on a large mesh without overtaxing your machine’s memory and processing power. When you select a section of the mesh and enter subset mode, SMS will stop displaying the parts of the mesh that were not selected. This allows SMS to ignore the elements and data on the parts of the mesh outside of the subset. This can help free up computing power while making changes to the subset mesh. When you are done making your changes, you can exit the subset mode to have SMS include your changes in the full-sized mesh.

While in subset mode, the mesh in the Project Explorer will be tagged with the (subset) suffix. Some of the specific commands that you can use in subset edit mode are:

• Commit Subset: this command takes you out of subset edit mode, and merges the changes made to the mesh subset with the rest of the mesh.
• Revert Subset: this command takes you out of subset edit mode, but does not retain any of the changes made to the mesh subset.

You may notice that "Refine" is listed as an option in the right-click menu while subset edit mode is active, however you are not able to refine elements in a subset. If you select "Refine" an error will appear stating "Command not available in subset edit mode."

Some actions that you are not able to perform while in subset edit mode are:

• Making changes on the border of the mesh subset.
• Creating a new mesh.
• Running a numerical model.
• Changing attributes such as boundary conditions on nodes, nodestrings, and elements.
• Renumbering node/nodestring/element IDs.

Head over to SMS and see how subset edit mode speeds up the processing time when editing large meshes today!

SRH-2D models in the Surface-water Modeling System (SMS) often use pairs of arcs to represent structures like culverts, weirs, bridges, and gates. For some projects, it matters for SRH-2D about how these arc pairs are drawn, and improperly drawn arcs can stand in the way between you and a successfully run model.

Arc pairs in SRH-2D models need to be drawn from left to right as if you are looking from upstream to downstream. This can get quite confusing, so here are a few tips for how to be able to tell which direction your arcs need to go by making use of display settings in the Display Options dialog.

If you’re not sure which direction is upstream and which is downstream, select 2D Mesh from the list on the left of the Display Options dialog and turn on Vectors. This requires having a dataset associated with the mesh that contains vector values. The vectors will display the direction the water is flowing, which makes it easy to be able to tell where upstream is. Now, to draw the arcs in the correct direction, imagine you are standing upstream and looking downstream. Then start the arc on your left and end it on your right. Both arcs need to be drawn in the same direction.

What do you do if you’ve already drawn the arcs and then you try to run your simulation and it fails? If the failure is caused by misdrawn arcs, the error will read "Program stopped due to the following: Linked Pair nodestring direction is wrong; please reverse them". The fix is simple if you have only one pair of arcs on your mesh: select both arcs in the Graphics Window, right-click, and select Reverse Arc Direction.

However, the existence of more than one arc pair can make solving this error a little more complicated. Rather than going around and either redrawing or reversing all the arcs, here's what you can do to pinpoint the problematic pair. First, open the Display Options dialog. On the Map tab check the box next to Annotations and click the Options button. In the Arc Annotation Options dialog, turn on Show arc direction arrow. Doing this will add arrows to the arc, pointing toward the end. This makes it easy to look at the arcs and see which ones are facing the wrong direction, at which point you can use the same steps as above to reverse the arc direction.

Head over to SMS and use this guide to help your SRH-2D model run more smoothly today!

When using the Groundwater Modeling System (GMS), it is important to understand how cells work in MODFLOW models, especially with conceptual models. Conceptual MODFLOW models are defined using feature objects such as points, arcs, and polygons on a grid. GMS processes each feature object separately, and occasionally there may be more than one feature object in a cell. MODFLOW is able to handle more than one boundary condition in a cell simultaneously, however, there are some things you should note.

The use of coordinates is essential to GMS as a whole, but not to MODFLOW. GMS uses coordinates to keep track of the exact location of feature objects relative to each other, as well as relative to the grid and other model data. Because the cell is the smallest unit of measurement in MODFLOW models, it only cares about the contents of the cell and not the specific location within it. All feature objects within the cell are mapped to the cell center and used for the cell calculations simultaneously.

When importing MODFLOW data that wasn't created in GMS, there are no coordinates tied to that data, so GMS uses the cell center as a reference and places all points there. This poses a problem as GMS requires that all points are assigned to unique coordinates, so GMS will generate an error message if any two or more points share an x, y, and z location. The way to fix this is pretty straightforward, although it can become tedious depending on the number of points on your grid. To solve this problem, follow these steps:

1. Open the Attribute Table dialog by double-clicking on a point in the Graphics Window.
2. Make sure the Feature type is set to "Points", and the Show dropdown is set to "All".
3. Check the box next to Show coordinates.

Now you can identify which points share the same coordinates and make the necessary changes. GMS only cares if more than one point has exactly the same coordinates in the x, y, and z directions. Offsetting a point even slightly in one of the three directions is enough for GMS to no longer have a problem, and the calculations will come out the exact same as long as the point remains within the original cell.

Head over to GMS and use these tips to make sure your MODFLOW simulation runs smoothly!

You may have already used the Hydraulic Toolbox to define a culvert for an SRH-2D model, but did you know its suite of calculators can assist you in many ways when creating a simulation in the Surface-water Modeling System (SMS)? The Hydraulic Toolbox is a software developed for the FHWA by Aquaveo, and there are many uses for the calculators, but today we’ll go over one example today to give you an idea of what you can do.

The Hydraulic Toolbox can assist you with calculations for other simulations, such as an SHR-2D urban hydraulics project in SMS. One of the main calculators that can be used for urban modeling with SRH-2D is the Curb and Gutter flow analysis.This calculator examines flow across storm drain inlets for various curb and gutter openings.

The Hydraulic Toolbox includes a macro that opens the Curb and Gutter Analysis calculator, or you can access it through the Calculators menu at the top of the window. This adds it to the Project Explorer under a “Project” folder. Once it has been added to the Project Explorer, double-click on the tool to open the calculator’s dialog. There are three main parts to the calculator: Gutter, Inlet, and a Parameters table. The Gutter section contains values for the gutter dimensions. This includes, but is not limited to, the gutter width, design flow, width of spread, etc.. The Inlet section is where factors defining the inlet location, inlet type, grate type, etc. are included. The Parameters table displays all the inlet data after it has been calculated by using the “Compute Inlet Data” button.

The Hydraulic Toolbox is separate from SMS, so as of SMS 13.3, data from the calculator will need to be entered manually into the relevant portions of SMS. The calculated data can easily be viewed from the calculator dialog itself, or you can export a document that contains a list of all of the data from the calculator. The Create Report function can be performed by right-clicking on the project folder in the Project Explorer, clicking the “Create Report” macro, or finding the Create Report option under the Calculators menu.

You can also attach notes to the project in the Hydraulic Toolbox. The options that allow you to create notes are found in the same three locations as the Create Report function, detailed above.

More in depth information about how the Curb and Gutter calculator, as well as the Hydraulic Toolbox in general, works can be found in the User’s Manual, which is accessed through the Help menu in the Hydraulic Toolbox. The Hydraulic Toolbox can be downloaded from this link.

The Curb and Gutter analysis calculator is just one example of how you can use the Hydraulic Toolbox with SMS. Head over to SMS and the Hydraulic Toolbox to explore the variety of calculators and how they can help you with your project today!