HEC-RAS Hydraulic Reference Manual
HEC-RAS Hydraulic Reference Manual
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HEC-RAS Hydraulic Reference Manual
Welcome to the HEC-RAS Hydraulic Reference Manual.
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Topics
Front Matter
Forward
Introduction
Theoretical Basis for One-Dimensional and Two-Dimensional Hydrodynamic Calculations
1D Steady Flow Water Surface Profiles
1D Unsteady Flow Hydrodynamics
2D Unsteady Flow Hydrodynamics
Basic Data Requirements
Geometric Data
Steady Flow Data
Unsteady Flow Data
Overview of Optional Capabilities
Multiple Profile Analysis
Multiple Plan Analysis
Optional Friction Loss Equations
Cross Section Interpolation
Mixed Flow Regime Calculations
Modeling Stream Junctions
Flow Distribution Calculations
Split Flow Optimization
Pressurized Pipe Flow
Estimating Ungaged Area Inflows
Modeling Precipitation and Infiltration
Modeling Bridges
General Bridge Modeling Guidelines
Hydraulic Computations through the Bridge
Selecting a Bridge Modeling Approach
Unique Bridge Problems and Suggested Approaches
Modeling Culverts
General Culvert Modeling Guidelines
Culvert Hydraulics
Culvert Data and Coefficients
Modeling Multiple Bridge and Culvert Openings
General Modeling Guidelines
Multiple Opening Approach
Divided Flow Approach
Modeling Gated Spillways, Weirs and Drop Structures
General Modeling Guidelines for Inline Structures
Hydraulic Computations through Gated Spillways
Uncontrolled Overflow Weirs
Modeling Lateral Structures
Drop Structures
Floodplain Encroachment Calculations
Encroachment Methods
Bridge, Culvert, and Multiple Opening Encroachments
General Modeling Guidelines for Floodway Analysis
Estimating Scour at Bridges
Computing Contraction Scour
Computing Local Scour at Piers
Computing Local Scour at Abutments
Total Scour Depths Inside The Bridge
Modeling Ice-covered Rivers
Modeling Ice Covers with Known Geometry
Modeling Wide-River Ice Jams
Stable Channel Design Functions
Uniform Flow Computations
Stable Channel Design
Sediment Transport Capacity
Performing a Dam Break Study with HEC-RAS
Inflow Flood Routing a Through Reservoir
Estimating Dam Breach Parameters
Downstream Flood Routing/Modeling Issues
Computational Time Step
Manning’s Roughness Coefficients
Downstream Storage, Tributaries, and Levees
Modeling Bridge and Culvert Crossings
Modeling Steep Streams
Drops in the bed Profile
Initial Conditions and Low Flow
Downstream Boundary Condition Considerations
Using 2D Flow Areas for Dam Break Analyses
References
Appendix
Flow Transitions in Bridge Backwater Analysis
Computational Differences Between HEC-RAS and HEC-2
Computation of the WSPRO Discharge Coefficient and Effective Flow Length
Sediment Transport Functions – Sample Calculations