George Mason University Department of Civil, Environmental and Infrastructure Engineering. Dr. Celso Ferreira

Transcription

1 George Mason University Department of Civil, Environmental and Infrastructure Engineering Dr. Celso Ferreira Exercise Topic: HEC GeoRAS Post-Processing 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 (Student), ArcCatalog , HEC-RAS

2 *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. 2

3 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. 3

4 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. 4

5 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]. 5

6 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. 6

7 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. 7

8 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. 8

9 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. 9

10 ArcGIS Convert Export to XML 1. Open ArcGIS and enable the HEC- GeoRAS 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. 10

11 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. 11

12 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. 12

13 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. 13

14 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. 14