HEC-RAS Online Help

Introduction

 

 

 

Welcome to the U.S. Army Corps of Engineers River Analysis System (HEC-RAS) developed by the Hydrologic Engineering Center. This software allows you to perform one-dimensional steady flow, unsteady flow calculations. Sediment transport computations will be added in a future version.

 

The HEC-RAS modeling system was developed as a part of the Hydrologic Engineering Center's "Next Generation" (NexGen) of hydrologic engineering software. The NexGen project encompasses several aspects of hydrologic engineering, including: rainfall-runoff analysis; river hydraulics; reservoir system simulation; flood damage analysis; and real-time river forecasting for reservoir operations.

 

This chapter discusses the general philosophy of HEC-RAS and gives a brief overview of the capabilities of the modeling system. Documentation for HEC-RAS is discussed, as well as an overview of this manual.

 

 

Contents

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General Philosophy of the Modeling System

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Overview of Program Capabilities

 

 

General Philosophy of the Modeling System

Overview of Program Capabilities
Introduction
General Philosophy of the Modeling System
Overview of Program Capabilities
User Interface
Hydraulic Analysis Components
Data Storage and Management
Graphics and Reporting
Installing HEC-RAS
Hardware and Software Requirements
Installation Procedure
Uninstall Procedure
Working With HEC-RAS - An Overview
Starting HEC-RAS
Steps in Developing a Hydraulic Model with HEC-RAS
Starting a New Project
Entering Geometric Data
Entering Flow Data and Boundary Conditions
Performing the Hydraulic Computations
Viewing and Printing Results
Importing HEC-2 Data
What You Should Know First
Steps for Importing HEC-2 Data
Reproducing HEC-2 Results
Getting and Using Help
Example Application
Starting a New Project
Entering Geometric Data
Drawing the Schematic of the River System
Entering Cross Section Data
Entering Junction Data
Saving the Geometry Data
Entering Steady Flow Data
Performing the Hydraulic Calculations
Viewing Results
Printing Graphics and Tables
Sending Graphics Directly to the Printer
Sending Graphics to the Windows Clipboard
Sending Tables Directly to the Printer
Sending Tables to the Windows Clipboard
Exiting the Program
Working With Projects
Understanding Projects
Elements of a Project
Plan Files
Run Files
Output Files
Geometry Files
Steady Flow Data Files
Unsteady Flow Data Files
Sediment Data Files
Hydraulic Design Data Files
Creating, Opening, Saving, Renaming, and Deleting Projects
Project Options
Entering and Editing Geometric Data
Developing the River System Schematic
Building The Schematic
Adding Tributaries into an Existing Reach
Editing The Schematic
Interacting With The Schematic
Background Pictures.
Cross Section Data
Entering Cross Section Data
Editing Cross Section Data
Cross Section Options
Plotting Cross Section Data
Stream Junctions
Entering Junction Data
Selecting A Modeling Approach
Bridges and Culverts
Cross Section Locations
Contraction and Expansion Losses
Bridge Hydraulic Computations
Entering and Editing Bridge Data
Bridge Design Editor
Culvert Hydraulic Computations
Entering and Editing Culvert Data
Bridge and Culvert Options
Bridge and Culvert View Features
Multiple Bridge and/or Culvert Openings
Entering Multiple Opening Data
Defining The Openings
Multiple Opening Calculations
Inline Structures (Weirs and Gated Spillways)
Entering and Editing Inline Structure Data
Lateral Structures (Weirs, Gated Spillways, Culverts, and Diversion Rating Curves)
Entering and Editing Lateral Structure Data
Linear Routing Option
Storage Areas
Storage Area Connections
Pump Stations
Cross Section Interpolation
River Ice
Entering and Editing Ice Data
Entering Ice Data at a Cross Section
Entering Ice Data Through a Table
Entering Ice Data at Bridges
Setting Tolerances for the Ice Jam Calculations
Viewing and Editing Data Through Tables
Manning's n or k values
Reach Lengths
Contraction and Expansion Coefficients
Bank Stations
Levees
Ice Cover
River Stationing
Node Names
Node Descriptions
Picture File Associations
Bridge Width Table
Weir and Gate Coefficient Table
Importing Geometric Data
GIS Format
USACE Survey Data Format
HEC-2 Data Format
HEC-RAS Data Format
UNET Geometric Data Format
MIKE11 Cross-Section Data
Geometric Data Tools
Graphical Cross Section Editor
Reverse Stationing Data
Set Ineffective Areas to Permanent Mode
Cross Section Points Filter
Fixed Sediment Elevations
Pilot Channels
GIS Cut Line Check
View Reach Connectivity
Datum Adjustment
Fix Overlapping Ineffective Areas
GIS Coordinates
Plot GIS Reach Bounds
Attaching and Viewing Pictures
Saving the Geometric Data
Performing a Steady Flow Analysis
Entering and Editing Steady Flow Data
Steady Flow Data
Boundary Conditions
Steady Flow Data Options
Saving The Steady Flow Data
Importing Data From The HEC Data Storage System (HEC-DSS)
Performing Steady Flow Calculations
Defining A Plan
Saving The Plan Information
Simulation Options
Starting the Computations
Performing an Unsteady Flow Analysis
Entering and Editing Unsteady Flow Data
Unsteady Flow Data
Boundary Conditions
Flow Hydrograph:
Stage Hydrograph:
Stage and Flow Hydrograph:
Rating Curve:
Normal Depth:
Lateral Inflow Hydrograph:
Uniform Lateral Inflow Hydrograph:
Groundwater Interflow:
Time Series of Gate Openings:
Elevation Controlled Gate:
Navigation Dam:
Internal Observed Stage and Flow Hydrograph:
Initial Conditions
Unsteady Flow Data Options
Saving The Unsteady Flow Data
Performing Unsteady Flow Calculations
Defining A Plan
Selecting Programs to Run
Geometric Pre-Processor
Unsteady Flow Simulation
Post-Processor
Simulation Time Window
Computation Settings
Simulation Options
Saving The Plan Information
Starting the Computations
Calibration of Unsteady Flow Models
Observed Hydrologic Data
River and Floodplain Geometry
Roughness Coefficients
River and Floodplain Storage
Hydraulic Structure Coefficients
Steps To Follow in The Calibration Process
General Trends When Adjusting Model Parameters
Calibration Suggestions and Warnings
Model Accuracy, Stability, and Sensitivity
Model Accuracy
Model Stability
Model Sensitivity
Viewing Results
Cross Sections, Profiles, and Rating Curves
Viewing Graphics on the Screen
Graphical Plot Options
Plotting Velocity Distribution Output
Plotting One Variable Versus Another
Sending Graphics to the Printer or Plotter
Sending Graphics to the Windows Clipboard
Stage and Flow Hydrographs
X-Y-Z Perspective Plots
Tabular Output
Detailed Output Tables
Detailed Output Table Options
Profile Summary Tables
User Defined Output Tables
Sending Tables to the Printer
Sending Tables to the Windows Clipboard
Viewing Results From the River System Schematic
Viewing Ice Information
Viewing Graphical Ice Information on the Screen
Viewing Tabular Ice Information
Viewing Data Contained in an HEC-DSS File
Exporting Results To HEC-DSS
Performing a Floodplain Encroachment Analysis
General
Entering Floodplain Encroachment Data
Performing The Floodplain Encroachment Analysis
Viewing the Floodplain Encroachment Results
Floodway Encroachments With Unsteady Flow
Troubleshooting With HEC-RAS
Built in Data Checking
Checking the Data as it is Entered
Data Checking Before Computations are Performed
Errors, Warnings, and Notes
Log Output
Steady Flow Log Output
Unsteady Flow Log Output
Viewing The Log File
Reviewing and Debugging the Normal Output
Viewing Graphics
Viewing Tabular Output
The Occurrence of Critical Depth
Computational Program Does Not Run To Completion
Computing Scour at Bridges
General Modeling Guidelines
Entering Bridge Scour Data
Entering Contraction Scour Data
Entering Pier Scour Data
Entering Abutment Scour Data
Computing Total Bridge Scour
Performing Channel Modifications
General Modeling Guidelines
Entering Channel Modification Data
Performing the Channel Modifications
Comparing Existing and Modified Conditions
Using GIS Data With HEC-RAS
General Modeling Guidelines
Importing GIS or CADD Data Into HEC-RAS
Completing The Data and Performing The Computations
Completing The Geometric Data
Entering Additional Cross Section Data
Performing The Computations and Viewing Results
Exporting Computed Results To The GIS or CADD
Stable Channel Design Functions
General Modeling Guidelines
General Command Buttons
Uniform Flow Computations
Solving for Slope, Discharge, or W/S Elevation
Solving for Bottom Width
Applying Uniform Flow Data to the Geometry File
Saving Uniform Flow Data
Stable Channel Design
Copeland Method
Regime Method
Tractive Force Method
Sediment Transport Potential
Advanced Features for Unsteady Flow Routing
Mixed Flow Regime
Dam Break Analysis
Entering Dam Break Data
Estimating Dam Break Parameters
HEC-RAS Output For Dam Break Analyses
Levee Overtopping and Breaching
Modeling Pump Stations
Navigation Dams
Pool Only Control
Hinge Point Only Control
Hinge Point and Minimum Pool Operations
Hinge Point and Minimum and Maximum Pool Control
Appendix A References
Appendix B
Supported HEC-RAS Data Exchange
The Import/Export Data File Structure
Records and Keywords
Values
Data Groups
Comments
HEC-RAS Channel Geometry Import File
Header
Stream Network
Cross Sections
HEC-RAS Model Results Export File
Water Surface Bounding Polygon
Import/Export Guidelines
Defining The Stream Network
Defining Cross Sections
Sample HEC-RAS Geometry Import File
Sample HEC-RAS Geographic Data Export File
Appendix C

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