Objective This tutorial will teach the user how to create a new RAS project, set a projection in HEC-RAS, download terrain data, create a RAS Terrain model, and reorder terrain tiles.

Data Files

The data for this tutorial are provided below.

BaseData.zip

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

Steps

Start a New HEC-RAS Project for the Merced River

  1. Open HEC-RAS
  2. Create a New Project for the Merced River
  3. Set the Folder
  4. Provide a Project Name

  5. Set the projection by dragging and dropping the projection.prj file onto the space "Drop a file here".

    The Projection area will update with the projection information
  6. Press the Create button to create your new RAS project


Download Data

  1. Create a new Terrain by pressing the Add button next to the Terrains group
     
  2. Provide a Name and press Create
  3. Zoom to the Area of Interest - the Merced River, Yosemite Valley, CA
    1. Drag-drop the shapefile for the area of interest - aoi.shp 
    2. Zoom to the shapefile extent
  4. Press the +Add button next to the new Terrain layer and select the USGS Importer

Import Using the Download Data Option

  1. Verify the view extents in the USGS Importer and Zoom/Pan as necessary
  2. Press the Query Area button

    This window will fill with the outlines of the tiles available for the area of interest
  3. Press the Filter button
  4. Select the Original data


    You can also type "orig" (or anything else) into the filter/search text option. Sometimes USGS metadata can be finicky, so filtering by filename substring can be very helpful.
  5. Download tiles of interest.  This can be preformed by individually or in bulk.
    1. Individually Download
      1. Press the Download Button for each individual tile.  As the tile downloads, you will see it turn green and show a small progress bar. When it finishes downloading, a colorized terrain tile will be displayed.
    2. Bulk Download
      1. Holding the Shift key, draw a box
      2. Holding the Control key, click on the tile to add or remove tiles
      3. Press the Download Selected button to download all selected tiles

  6. Press the Settings button
  7. Set the Rounding to 1/16 and leave the Merge Tiles option On
  8. Press the Import button

Import Data Files (Alternative to Download)

If the USGS Importer fails due to server error or poor internet connectivity, load the terrain manually.

  1. Select the Terrain layer
  2. Press the +Add button next to the new Terrain layer and select Import File option
  3. Navigate to your project directory
  4. Select the USGS_Original.tif file
  5. Press the Import button
  6. Zoom to the extents of the new Terrain layer.

Investigate Terrain

  1. Select the RAS Terrain layer
  2. Select the Open Editor button at the top of the Model panel 

    If you had multiple terrain resolutions, the Importer would show multiple layers.  In the example below, the "Merged" dataset is the USGS Original Data.  The "Merged (1)" dataset is USGS 1-meter data.  As you click on each layer, that data is highlighted in the editor.

    If you want to remove a dataset, press the Delete button next to the layer.

  3. Activate the Layer tab and investigate the Raster Symbology Settings for the Terrain layer
    1. Toggle on/off Grayscale
    2. Interact with the Opacity with the Open Streetmap background data
    3. Interact with the Hillshade parameters
    4. Toggle on/off Plot Contours and enter an Interval
  4. Turn on Satellite Imagery and interact with the Opacity
  5. Create your own color ramp
    1. Zoom into an area of interest
    2. Use the cursor to get an understanding for the range elevation values
    3. Choose Linear for the Interpolation method
    4. Set the Min and Max values in symbology
    5. Zoom in and experiment with the Update to View button which maximizes the resolution of the color scale to the maximum and minimum of the zoomed elevations instead of the elevations of the whole terrain.


Cut a Profile

  1. Zoom to an area of interest
  2. Select the Profile Lines layer and turn in on
  3. Select the Edit Tool
    1. Double-click to start the line and double-click to finish the line
  4. Right-click on the line and choose the Plot | Terrain Profile menu option

    A window with a profile plot will be opened 


Start a New HEC-RAS Project for the Potomac River

  1. Following the steps above, create a new Project for the Potomac River
    1. Use the USGS_Albers_Equal_Area.prj in the 'Potomac' directory for the projection.

Create a New Terrain From Files

  1. Create a new Terrain.
  2. Select the Terrain layer
  3. Press the +Add button next to the new Terrain layer and select Import File option
  4. Navigate to the Potomac/Terrain Data directory
  5. Select all 5 of the the tif files
  6. Press the Import button
  7. Zoom to the extents of the new Terrain layer.

Reorder the terrain tiles to make a more detailed terrain

The 5 terrain tiles include:

  • lidar of varying quality
  • channel bathymetry
  • floodwalls
  1. Right-click the Terrain and open the Terrain Editor:
  2. In the Terrain Editor select each of tiles to visualize their extents.
  3. Reorder the tiles by drag-dropping the tiles to make the most detailed terrain possible. 
  4. When you are done setting the order, close the Terrain Editor and explore the terrain in the map window.