HEC-RAS LAB #1 TRIANGULAR OPEN CHANNEL Page 1 of 10 Project File: LAB_1.PRJ HEC-RAS input files for example problem with single triangular open channel. Input data for open channel, copy cross sections, and interpolate cross sections.. Generate program files, perform analysis and review output. Discussion of output formats available from HEC-RAS (e.g., charts, tables, figures). Problem Statement: One river reach (River TREEO, Reach Main) discharges into a downstream basin outlet. The peak discharge has been calculated at 50 cfs, using other methodology for input into HEC-RAS. The reach is 800 feet long. To Do: Prepare a backwater profile analysis along the creek. NOTE: Projects consist of multiple files with multiple file extensions. Extension: PRJ G** F** P** R** O** File Description Main Project File Geometry File Steady Flow File Plan File Run File (contains results) Output File (used to create graphs and tables) HEC-RAS LAB #1 TRIANGULAR OPEN CHANNEL Page 2 of 10 Lab #1 Steps to Develop the HEC-RAS Model: 1. Open HEC-RAS Go to Windows Start, Programs, HEC, and click on the HEC-RAS icon. 2. Enter Project Information Select File, New Project Create Directory: Problems (enter) Enter Short Project ID and Project Filename (extension is added automatically) Short Project ID: RAS LAB 1 Project Filename: RASLAB1 (extension is added automatically) Add Project Description: RAS LAB # 1 (optional information) HEC-RAS 3. LAB #1 TRIANGULAR OPEN CHANNEL Page 3 of 10 Begin building model. Start Geometric Data Select Edit, Geometric Data Reaches Cross Sections 4. Add Reaches and Cross Sections Draw Reach by Selecting the Reach Button (Click Once) Move over screen to draw reach Define Reach proceeding from upstream to downstream With cursor in draw screen, click mouse button once to start Move cursor, click mouse button once to add point, change direction At downsteam point, doubleclick mouse button to end HEC-RAS 4. LAB #1 TRIANGULAR OPEN CHANNEL Page 4 of 10 continued Enter River Name (TREEO) and Reach Name (MAIN) 5. Add Cross Sections to Reach Select Cross Section Button (click once) (optional) follows: Select Options, Add a new Cross Section Enter Station Location (1.0)and Cross Section Description Station must be numerical value and are defined as lower station downstream, higher stations upstream HEC-RAS LAB #1 TRIANGULAR OPEN CHANNEL Page 5 of 10 Cross Section Data Cross Sections typically enter left to right looking downstream Cross Section Stationing in left column Elevation Data in right column Triangular Channel Station Elevation 0 7 30 6 50 4 70 6 90 7 THIS IS A TRIANGULAR CHANNEL,10:1 SIDE SLOPE Enter downstream reach lengths for main channel and overbanks No downstream reach lengths for most downstream section Furthest downstream section defined by boundary conditions Add Manning’s n value for main channel and overbanks .04 .035 .04 Outer Banks are outside Main Channel. Must correspond to a cross section station. Left Main Channel Bank at 30 Right Main Channel Bank at 70 Repeat for additional Cross Sections Use Add, Copy, Interpolate Copy - Define New Cross Section Name: 9.0 Adjust Elevation: +4 feet (1/2 percent slope) Revise Downstream Reach Lengths: 800 feet Exit Cross Section Data Editor Interpolate - On main geometry screen Tools, XS Interpolation, Within a Reach Maximum distance: 100 feet Interpolate XSs, Close Interpolated Cross Sections have “*” by station name Interpolated Cross Sections can be made permanent by editing the name in the cross section editor and removing the asterisk HEC-RAS LAB #1 TRIANGULAR OPEN CHANNEL SAVE GEOMETRIC DATA, file name automatically assigned 6. Start Steady Flow Data Select Edit, Steady Flow Data Page 6 of 10 HEC-RAS LAB #1 TRIANGULAR OPEN CHANNEL Page 7 of 10 Enter the Flow for the River TREEO and Reach Main : (this is the flow at the upstream cross section of each) 50 cfs Enter Boundary Conditions Most Downstream Channel - use Known Water Surface Elevation - Critical Depth, determined by size of channel - Normal Depth defined by channel shape, slope, and flow - Rating Curve (user defined) - HEC-RAS will normally set these automatically Normal Depth, slope = 0.005 SAVE STEADY FLOW DATA, file name automatically assigned HEC-RAS 7. LAB #1 TRIANGULAR OPEN CHANNEL Page 8 of 10 Simulate Backwater Analysis Select Run, Simulate Select Geometry File: TREEO LAB 1 Select Steady Flow File Save Steady Flow Analysis File Description: TREEO LAB 1 8. Short Form: LAB 1 COMPUTE Options within this segment allow for error checking, precision, etc. See FINISHED COMPUTATION screen for errors and warnings. Close Window EXIT STEADY FLOW ANALYSIS HEC-RAS 9. LAB #1 TRIANGULAR OPEN CHANNEL Page 9 of 10 View Results View Graphics Cross Sections Profiles Rating Curves (multiple profiles) X-Y-Z Perspective (3-D) View, X-Y-Z Perspective Plot View, Water Surface Profile print using File, Print from screen or copy to Windows clipboard HEC-RAS LAB #1 TRIANGULAR OPEN CHANNEL Page 10 of 10 View Tables Cross Sections/Culverts/Bridges Profile Table Summary Errors/Warnings print using File, Print from screen or copy to Windows clipboard Cross Section 2.0: Water Surface Elevation = 5.94 feet 10. Generate Report - File, Generate - Select Filename SAVE PROJECT, file name assigned in step 1.