HEC-RAS LAB #1 Page 1 of 10TRIANGULAR OPEN CHANNEL

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: File Description

PRJ Main Project FileG** Geometry FileF** Steady Flow FileP** Plan FileR** Run File (contains results)O** Output File (used to create graphs and tables)

HEC-RAS LAB #1 Page 2 of 10TRIANGULAR OPEN CHANNEL

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 InformationSelect File, New Project

Create Directory: Problems (enter)Enter Short Project ID and Project Filename (extension is added automatically)Short Project ID: RAS LAB 1Project Filename: RASLAB1 (extension is added automatically)

Add Project Description: RAS LAB # 1 (optional information)

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3. Begin building model.Start Geometric Data

Select Edit, Geometric Data

4. Add Reaches and Cross SectionsDraw Reach by Selecting the Reach Button (Click Once)

Move over screen to draw reachDefine Reach proceeding from upstream to downstream

With cursor in draw screen, click mouse button once to startMove cursor, click mouse button once to add point, change directionAt downsteam point, doubleclick mouse button to end

Reaches

Cross Sections

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4. continued

Enter River Name (TREEO) and Reach Name (MAIN)

5. Add Cross Sections to Reach

Select Cross Section Button (click once)

Select Options, Add a new Cross Section Enter Station Location (1.0)and Cross Section Description

(optional) Station must be numerical value and are defined as follows:

lower station downstream, higher stations upstream

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Cross Section DataCross Sections typically enter left to right looking downstream

Cross Section Stationing in left columnElevation Data in right column

Triangular ChannelStation Elevation0 730 6 THIS IS A TRIANGULAR 50 4 CHANNEL,10:1 SIDE SLOPE70 690 7

Enter downstream reach lengths for main channel and overbanksNo downstream reach lengths for most downstream sectionFurthest 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 SectionsUse Add, Copy, Interpolate

Copy - Define New Cross Section Name: 9.0Adjust Elevation: +4 feet (1/2 percent slope)Revise Downstream Reach Lengths: 800 feetExit Cross Section Data Editor

Interpolate - On main geometry screenTools, XS Interpolation, Within a Reach

Maximum distance: 100 feetInterpolate XSs, Close

Interpolated Cross Sections have “*” by station nameInterpolated Cross Sections can be made permanent by editing the name in the cross section editor and removing the asterisk

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SAVE GEOMETRIC DATA, file name automatically assigned

6. Start Steady Flow Data

Select Edit, Steady Flow Data

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Enter the Flow for the River TREEO and Reach Main : 50 cfs (this is the flow at the upstream cross section of each)

Enter Boundary ConditionsMost 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

SAVE STEADY FLOW DATA, file name automatically assigned

Normal Depth,slope = 0.005

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7. Simulate Backwater Analysis

Select Run, Simulate

Select Geometry File: TREEO LAB 1Select Steady Flow File

Save Steady Flow Analysis FileDescription: TREEO LAB 1 Short Form: LAB 1

8. COMPUTEOptions within this segment allow for error checking, precision, etc.

See FINISHED COMPUTATION screen for errors and warnings.Close Window

EXIT STEADY FLOW ANALYSIS

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9. View Results

View GraphicsCross SectionsProfilesRating 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

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View TablesCross Sections/Culverts/BridgesProfile TableSummary 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.