Objective - This tutorial will take the user through a guided tour of HEC-RAS, identifying key capabilities such as downloading an example model and how to report a bug.

Data Files

The data for this tutorial is provided below.

Cabin.7z

These data are for demonstration purposes only and should not be used for engineering analysis.


Steps

Step 1: Installation

Download RAS 2025 from the URL provided in the class. This is an as-yet unreleased build for the class, so the latest alpha from our website won't work.

Extract to a directory of your choice.

For maximum compatibility with Windows (and various anti-virus products) this should not be in your user profile (e.g. do not put it under C:\Users).

When you launch the software, you should see a first-launch screen with a few settings to choose from.

You can change these default settings if you'd like. If your default project directory is under a corporate-managed OneDrive location, it may be useful (for performance and data-management) to move it out of that directory. Very large models can have a hard time backing up reliably to such locations.

Step 2: Login

In this step, we're going to authenticate with the HEC servers. This will give you access to the models used in the class workshops.

From the main RAS launch screen, open the Settings pane (button in the lower-right corner) and click Credentials. Credentials will be provided in the classroom, and will be valid for the duration of the class. Log in with the credentials provided.

If the login was successful, you should immediately launch into our Development Tools page. If you select the Model Library tab on the left, you should have access to the >class folder.

Once you're authenticated, the Development Tools will always be available from the main launch screen.

Development Tools require logging in to a credentialed account.  If you don't see the Development Tools button, login.

Now, let's make sure we're on the class-build version of the software. In the upper-right corner, click the Update Available button.

In the dropdown for your installation, select the Nightly channel, then select class-build. Click Update To Latest to update RAS. This is a helpful test of our new updater system, so let us know if you run into any issues!

We may update RAS 2025 several times throughout the class as we fix bugs and improve the software. The updater will be available from the main splash screen....you'll see!

Step 3: Download a Dataset

Go to the Development Tools, select the Model Library tab and download class/workshops/intro-to-ras-2025 by right-clicking it, and selecting open.

This will download a .zip of the model to your machine, extract it, and put it in your default project folder. The dataset will open automatically.

Let's explore the dataset. The easiest way to understand the contents of the model is to click the Project Browser tab, docked in the map window.

The Project Browser is a full catalog of all layers and data-files that the model owns or knows about. Expand and explore the layers in the tree, and answer the following questions. (There may be multiple ways to answer some of these questions).

  1. What projection is the model in? What is the unit system?
  2. How many Geometries, Boundary Conditions, and Plans does the model have?
  3. When (approximately) was the model built?
  4. How many terrain files are there? What are the cell size(s)?
  5. What n-values are being used? Where are these values coming from?

Step 4: The Map

Let's investigate the model visually, to see what's in it. If it's not already on, turn on the Terrain layer.

The Layer tab (docked to the right by default) has visualization information for the currently-selected layer. Tweak the terrain visualization how you see fit.

Selecting the layer in the Model tree (on the left) will make the Components and Layer tabs reflect various properties about that layer. Select different layers to see what settings are available. Broadly, the Components tab is for data (anything that affects the computations), and the Layer tab is for visualization and symbology.

Step 4.1: Base Maps

The globe icon in the map control bar has base maps. Play around with these settings to see what's available. With USGS Hillshade and Open Street Maps on, you should be able to see a nice shaded relief map of the surrounding area.

Once you're satisfied with the base map symbology, zoom around the area to see where we are.

Make sure to play with the Satellite Imagery and the associated Opacity.

Step 4.2: Map Hover

Turning on a layer in the Model tree will render it in the map window, and will also enable mouse-hover sampling. 

Turn on Terrain, N Values, and Classifications separately, then all at once. Hover the map to see the values sampled under your mouse.

Select the N Values layer in the tree. What n-values are being used here? Where are they coming from?

Step 4.4: Zoom Extents

The Extents tab allows you to save your current zoom-extent and get back there later. Save a few Views, name them (via double-click), and zoom back and forth to different areas in your model.

Step 5: Model Errors

The modeler who built this is clearly very inexperienced, and has made some key mistakes. Let's try to identify them with the tools available.

Map the result that was run as Plan 2. Turn it on in the tree, then animate with the profile slider up at the top of the screen.

The modeler said it was just a simple hydrograph that ramped up and down over 24 hours, but something doesn't seem right as you scrub through time. One of the mapped time steps looks much deeper than the others. What time did this happen?

To see how the result changed through time, the easiest way to see this is by right-clicking anywhere on the map (while your result is mapping) and clicking Query Result Time Series.

Step 5.1: Boundary Condition Fail

In the previous step, you should have seen a big spike in the depth time-series. This doesn't look right.

You can see what Boundary Condition that Plan 2 is associated with by selecting it, then looking at the Components pane.

You can see information about your boundary condition data in the Boundary Condition Editor. All editors can be accessed by right-clicking the layer of interest, or via a double-click on that layer. The Boundary Condition Editor has different layouts depending on how narrow your screen is. You can make it wider to show a chart side-by-side with the table, or click the Chart tab when it's in compact mode.

Select both boundary condition lines. Does something look wrong with either of them?

After you figure out what's wrong, fix the issue how you see fit.

Let's do a little cleanup. Rename the boundary condition lines to something more meaningful by double-clicking them in the list on the left.

Step 5.2: What LIDAR?

Despite the modeler telling us they grabbed LIDAR data, the terrain looks terrible. Find out what they did wrong, and fix it.

The Terrain Editor has good ways to visualize this by selecting the individual files in the Layers list.


If you need to see how big your terrain cells are, don't forget you can use the Measure Tool and the Scale Bar in the map window to get a sense of scale.

When you find the issue, go to the next step to cut a profile line across the channel and plot it (before and after) to show the difference/improvement.

Step 5.3: Cut a Profile Line

Let's see what the terrain and results look like. Draw a Profile Line by selecting the pre-made Profile Lines layer and using the Edit Tool.

To modify any layer with the editing tools, that layer has to be selected in the Model tree, and the Edit Tool icon must be selected.

  • To create a new line
    • double-click to start a line
    • single-click to append
    • double-click to end the line
  • To edit an existing line
    • double-click to start editing
    • click and drag to move a vertex
    • click to insert a new vertex 
    • double-click to end editing

Plot a Terrain Profile. The Profile Lines layer must be selected to interact with it on the map. While you're there, practice docking it in the map window by clicking and dragging the tab header.

Zoom into the terrain profile to see what the approximate cell-size is. Does it match what you expect?

You can also draw a Profile Line across the channel and query a Flow Time Series. Remember that flow convention in RAS is that positive flow means left to right looking downstream. Does the flow match your expected values?

Step 5.4: Interesting Mesh...

The modeler clearly built their mesh very... enthusiastically. It's got resolution in the wrong spots and it's using some poor modeling practices. Let's roll it back to a different point in time.

Go to the Project Browser. Expand out Base Geometry and its Backups. Select each backup, mapping it in the main screen to see what they've worked on. This will only show the Conceptual Mesh (wireframe), not the full computational mesh. Backups are saved for you automatically every few minutes while you're editing.

Restore the backup named Backup-200ft-tri. Click the Save as New Geometry button to pull it into your main model.

Currently we can't restore it over the top of your current geometry, so you'll have to save it as a new geometry. You're free to rename your backups on disk - we're in the process of creating better tooling around this.

Backups are stored with the bare minimum of information needed - just the conceptual mesh. Regenerate the mesh for this backup.

The mesh from this backup should be a simple coarse TIN with 1-2 triangles across the channel - good enough for routing flow. We don't need anything more accurate for this model.

Give Base Geometry - Backup-200ft-tri a better name before we move on.

Geometries that are restored from backup do not have associations immediately mapped. Select the new geometry layer, and change these associations (in the Components pane).

 

Step 6: Report a Bug

In the incredibly unlikely event of a bug (cough), we want to make sure you know how to report them.

The bug reporter is available in two places: the launch screen in the lower-right corner, and the Help menu in the main RAS window when you have a project open.

Submit a bug report. Please start the title with "CLASS - " so we can find it easily in our tracking system. 

If you found an actual bug, please describe it fully and submit. If not - submit a bug report anyways. Tell us something about yourself.