HEC-RAS Version 3.1HEC-RAS Version 3.1OverviewOverview

Presented by:Presented by:

HEC-RAS

US Army Corps of Engineers’

Hydraulic Engineering Center

River Analysis System

Version 2.0 (Windows 3.1 or later) - April 1997

Version 2.1 (Windows 95/98 or NT(4.0)) - October 1997

Version 2.2 (Windows 95/98 or NT(4.0)) - September 1998

Version 3.0 (Windows 95/98 or NT(4.0)) - 2001

Version 3.1 (Windows 95 or higher) January 2003

NRCS is adopting the Corps of Engineer's HEC-RAS (River Analysis System) for computation of water surface profiles. Use of the NRCS program WSP2 is being phased out as NRCS engineers become trained and experienced with HEC-RAS.

National Bulletin No. 210-01September 30, 2000

• NRCS will no longer support our WSP2.• Announce adoption of Hydrology Engineering Center-

River Analysis (HEC-RAS).• HEC-RAS Leadership - National Water and Climate

Center and NRCS HEC-RAS Team

Beltsville, MD Bill Merkel 301-504-3956Beltsville, MD Quan D. Quan 301-504-3952ForthWorth, TX Jon Fripp 817-509-3771Michigan Tom Bourdon 517-324-5240Minnesota Pete Cooper 651-602-7884NewMexico Dan Murray 505-761-4436NewYork Clyde Giaquinto 315-477-6540NorthDakota Dennis Reep 701-530-2091Oklahoma Gary Utley 405-742-1229Portland, OR Dan Moore 503-414-3054Washington John McClung 509-323-2952Iowa Matt Seidl 515-323-2239

Email the entire HEC-RAS Team: hecrasteam@wcc.nrcs.usda.gov

HEC-RAS Team

HEC-RAS is software that allows the user to perform one dimensional steady and unsteady flow river hydraulics calculations

go to: www.hec.usace.army.mil

Hydraulic Information - It’s Important

• Water surface profiles

• Hydraulic Parameters

Hydraulic Parameters

• Velocity

• Depth

• Shear

• Width

• Area

• etc

Hydraulic Computer Models: Why do we care?

• Direct Measurements: hard, expensive, dangerous

• Analytical: predictive

Hydraulic Models Steady Flow

– WSPRO (FHA)

– WSP2

– HEC-2 (last one out in 1991)

– HEC-RAS (released 1995)

Unsteady Flow

– UNET

– DAMBREAK

– HEC-RAS

Comparison of HEC-2 and HECRAS

• Improved conveyance calculations.

• Mixed flow - supercritical, subcritical

• Bridge hydraulics - more options

• Culvert hydraulics - more options

• Junctions - both energy and momentum

• Others - interpolation, unsteady flow, more section definition, etc

Comparison of WSP2 and HEC-RAS

• DOS command line - batch jobs

• One dimensional steady flow

• Subcritical and critical flows

• No graphics

• Windows graphical interface for Win3.1, Win95/98, and WinNT

• One dimensional steady flow

– floodway encroachments

– unsteady flow

– sediment transport

• Subcritical, critical, mixed and supercritical flows

• Graphical display of all geometric data and output including 3D views

WSP2 HEC-RAS

Comparison of WSP2 and HEC-RAS

• Uses friction slope from upstream x-section only (i.e. upstream x-section represents entire reach).

• Uses average of friction slope from upstream and downstream x-sections.

WSP2 HEC-RAS

• Hydraulic Analysis Components

• Graphical User Interface– Data Input

– Output

Hydraulic Capabilities

• Steady flow water surface profiles - single reach, dendritic, mixed flow regime.

• Unsteady flow simulation- full network of open channels, adapted from UNET

• Sediment transport/Movable boundary- long term trends of scour and deposition (not ready, only bridge scour)

• Flows

• Geometry– Cross Section– Spacing– Structures

• Manning’s n

• Calibration Data

• Graphical

• Tabular

• Profile

• Section

Other Applications and Capabilities

• Bridge Scour• Culverts• Drop Structures• Hydraulic Jumps• Split Flow• Lateral Weirs• In Channel Weirs• Gated Spillways and Weirs• Vertical Variation in Roughness• GIS import and export features (HEC-GeoRAS 3.1 with

ArcView)

How do you get HEC-RAS?

The HEC-RAS software and manual are available for free download from HEC at the following internet address:

http://www.hec.usace.army.mil/

Also available through NRCS CCE and NWCC web site.

HEC-RAS - Documentation

User’s Manual: provides an introduction and overview of the modeling system, installation instructions, how to get started, a simple example, detailed descriptions of each of the major modeling components, and how to view graphical and tabular output

Hydraulic Reference Manual: describes the theory and data requirements for hydraulic calculations

Applications Guide: contains a series of examples that demonstrate various aspects of HEC-RAS.

Hardware & Software Requirements for HEC-RAS

• IBM compatible machine with 486 or higher• 10 MB free space on hard drive (20 recommended)• 16 MB of RAM for Windows95/98 and 24 MB for

Windows NT (32 or more is recommended)• Mouse• Windows95/98 or Windows NT (4.0 or higher)• Color VGA or better video display

Limitations

• Flow is constant with respect to time (unsteady is optional)

• Flow is gradually varied with distance

• Dominant flows in x direction (1-D)

• Channel slopes less than 1:10H

Where do you go for help?• On line help• HEC-RAS documentation• HEC-RAS Support Team from NRCS

(email: hecrasteam@wcc.nrcs.usda.gov)

The HEC-RAS software is an engineering tool.

Not a replacement for sound engineering.

Agenda

• Tuesday: Hydraulics Review, Basic I/O, Bridges• Wednesday: Culverts, Tributaries, weir and drop

structures• Thursday: Other features, Channel Modification,

Unsteady Flow

The EndThe End