Objective - This tutorial will take the user through a guided tour of HEC-RAS 2025, 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

This data is for demonstration purposes only and should not be used for analysis.

Steps

Step 1: Installation

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)
  • Click Credentials.
  • Log in with the credentials provided
    • Credentials will be provided in the classroom, and will be valid for the duration of the class.

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.


Step 3: Download a Dataset

  • Go to Development Tools
  • Select the Model Library tab
  • Download class/workshops/1_3_intro-to-ras-2025 by right-clicking it, and selecting open.
    • This is the same dataset linked at the top of the workshop. If you already downloaded it above, you don't need to download it again.

This will download a .zip of the model to your machine, automatically 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)
  • 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 the created Views (via double-click)
  • Zoom back and forth to different areas in your model using the Views

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 and make sure the result is also selected.
    • 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?

For the easiest way to see how a result changed through time:

  • Right-click anywhere on the floodmap (while your result is turned on and shows up in the map)
  • Click 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 the Plan 2 Plan (not Plan 2 result), 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.

Try utilizing the terrain editor to visualize the multiple raster comprising our terrain:

  • Open the Terrain Editor by right-clicking the terrain and clicking Open Editor
  • Select USGS_Resampled30m
  • Select Lidar


If you need to see how big your terrain cells are, get a sense of scale. Back in the main map, try using:

  • The Measure Tool (in the top left of the main map window)
  • The Scale Bar (in the bottom right of the main map window)

Identify the issue with the modeler's terrain utilizing the terrain editor, measure tool, and scale bar.

When you figure out the issue, go to the next step to use profile lines and understand the improvement/difference you've made.

Step 5.3: Cut a Profile Line

Let's see what the terrain and results look like. Start by drawing a profile line:

  • Select the Profile Lines layer 
  • Select the Edit Tool (pencil icon)

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 intermediate points
    • double-click to end the line
  • To edit an existing line
    • double-click to start editing
    • single-click and drag to move a vertex
    • single-click to insert a new vertex 
    • double-click or click Escape to end editing

Plot a Terrain Profile:

  • Select the Profile Lines layer (it must be selected to interact with it in the map)
  • Right-click your line from earlier
  • Click Plot, then Terrain Profile.
  • When the chart opens, try 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...

  • Expand the geometry in your model
  • Turn on the Conceptual Mesh and Mesh nodes.

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 Geometries, then Base Geometry, then Backups.
  • Select each backup: you will see a preview map in the main screen to see what was done previously.
    • Note: This will only show the Conceptual Mesh (wire frame), 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 by clicking the Save as New Geometry button.
    • The restored backup will now show in the model tab

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 newly created geometry layer
  • Change its 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.