Tutorial - PostProcessing

George Mason University
Department of Civil, Environmental and Infrastructure Engineering
Dr. Celso Ferreira
Exercise Topic: HEC – GeoRAS Post-Processing
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Objectives: This tutorial is designed to walk you through the process of creating flood maps products from a HEC-RAS simulation
including extracting flood delineation polygons, water depths and velocity rasters. It also includes running a simple steady flow
simulation with HEC-RAS from a previously created HEC-GeoRAS set-up.
**Refer to the HEC-GeoRAS User Manual for definitions and context of the steps and tools in this tutorial, found in the Help Menu of the GeoRAS toolbar.**
Tutorial DEM obtained from GMU Campus Lidar file (provided)
Versions used for this tutorial: HEC-GeoRAS 10.1, ArcMap 10.2.2 (Student), ArcCatalog 10.2.2, HEC-RAS 4.1.0
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*Continued from Intro GeoRAS Tutorial
Modify GIS Data in HEC-RAS
1. Save imported project geometry.
2. Click the icon for
“Bridge/Culvert”.
3. Note that the bridge geometry
did not import properly (this is
common).
4. Click the icon for
“Deck/Roadway”.
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5. Enter the distance from the
upstream bridge face to the
closest upstream cross section.
6. Enter the bridge width.
7. Enter sample bridge deck
geometry data.
8. Click “OK”.
*Refer to the HEC-RAS tutorial for
details on each field.
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Ensure <500 Points Per Cross Section
1. Select “Cross Section Points
Filter” from the Tools menu in
the Geometric Data window.
2. Select the “Multiple Locations”
tab.
3. Select “All Rivers” from the River
drop-down menu.
4. Click the arrow to move the River
selection to the Selected
Locations box.
5. Click “Near and Colinear Filter”.
6. Confirm that the box for “more
than 500 points” is checked.
7. Click “OK”.
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Enter Flow Data and Boundary
Conditions
1. Select the “Steady Flow” icon
from the main window toolbar.
2. Enter sample flow data for each
reach.
3. Click “Reach Boundary
Conditions”.
4. Highlight the “Upstream” cell for
the first reach.
5. Click “Known W.S.” [water
surface].
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6. Enter a sample water surface
elevation.
7. Repeat Steps 4 through 6 for the
other two reaches.
8. Click “OK”.
9. Click “Apply Data”.
10. Close the Steady Flow Data
window.
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Run HEC-RAS Simulation
1. Select the “Steady Flow
Simulation” icon from the main
toolbar.
2. Select the geometry and flow
data.
3. Confirm that “Subcritical” flow is
selected.
4. Click “Compute”.
5. Click “Close” after the successful
simulation run.
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6. Click the Geometric Data icon.
7. Select the new Simulation Run
data from the WS Extents dropdown menu.
8. Observe the water boundaries
within each reach resulting from
the sample flow data.
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Export HEC-RAS Results
1. Select “Export GIS Data” from the
main File menu.
2. Confirm that all reaches (3/3) are
selected.
3. Confirm that the “Water
Surfaces” is checked.
4. Confirm that the new Simulation
Run profile data is selected.
5. Confirm that the River
Centerlines are selected.
6. Check the box for “User Defined
Cross Sections”.
7. Select the desired output
parameters (Reach Lengths, Bank
Stations, Ineffective Areas,
Blocked Obstructions, Manning’s
n).
8. Click “Export Data”.
9. Click “OK”.
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ArcGIS – Convert Export to XML
1. Open ArcGIS and enable the HECGeoRAS toolbar.
2. On the GeoRAS toolbar, click the
“Import RAS SDF File” icon.
3. Select the file that was exported
from HEC-RAS.
4. Click “Open”.
5. Click “OK”.
6. Click “OK” upon successful
conversion to XML format.
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Setup New Project
1. Select “Layer Setup” from the
RAS mapping drop-down menu.
2. Select “New Analysis” and assign
a file name.
3. Select the XML file containing the
RAS export.
4. Select the radio button for
“GRID” and select the original
GMU DEM.
*The DEM must be saved to the
same folder as the exported data
(current workspace).
5. Select the folder location of the
current workspace.
*Must be folder, not a
geodatabase.
6. Click “OK”.
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Populate New Project
1. Select “Import RAS Data” from
the RAS Mapping drop-down
menu.
2. Confirm that the exported XML
file is selected.
3. Click “OK”.
4. Click “OK” upon successful
import.
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Create Water Surface Layer
1. Select “Water Surface
Generation” from the RAS
Mapping > Inundation Mapping
drop-down menu.
2. Select the imported Simulation
Run profile.
3. Click “OK”.
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Calculate Water Extents
1. Select “Floodplain Delineation
Using Rasters” from the RAS
Mapping > Inundation Mapping
drop-down menu.
2. Select the imported Simulation
Run profile.
3. Click “OK”.
4. Click “OK” upon successful
mapping.
**Discontinuities in the flow are
expected. Only a sample bridge was
drawn during this exercise, but all real-life
bridges and culverts still exist in the DEM.
They have a surface elevation higher than
the simplified flow path imported from
RAS.
As long as the flow volume does not
exceed bridge and culvert capacities,
there is no impact to the model results
shown at right.
To be technically correct, or to accurately
model extremely high flow volumes, all
bridges and culverts should be drawn.
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