HEC-RAS program that models the hyHEC-RAS is a computer program that draulics of water flow through natural rivers and other channels. channels. The program is one-dimensional one-dimensional,, meaning that there there is no direct direct modeling modeling of the hydrauli hydraulicc effect effect of cross section shape changes, bends, and other two- and three-dimensional aspects of flow. The program was developed by the US Department of Defense, Army Corps of Engineers in Engineers in order to manage the rivers, harbors, and other public works under their jurisdiction; it has found wide acceptance by many others since its public release in 1995.
adapted from Dr. Robert L. Barkau’s UNET package. HEC-RAS is equipped to model a network of channels, a dendritic system or a single river reach. Certain simplifications must be made in order to model some complex flow situations using the HEC-RAS one-dimensional approach. It is capable capable of modeling subcritical, subcritical, supercritisupercritical, and mixed flow regime flow along with the effects of bridges, bridges, culverts, culverts, weirs, and structures.
2
Use
HEC-RAS is a computer program for modeling water flowing through systems systems of open channels and computing water surface surface profiles. profiles. HEC-RAS finds particular particular commercial application in floodplain management and flood and flood insurance studies studies to evaluate evaluate floodway floodway encroachments. encroachments. Some of the additional additional uses are: bridge bridge and culvert culvert design and analysis, levee studies, and channel modification studies. studies. It can be used for for dam breach breach analysis, analysis, though though other modeling methods are presently more widely accepted for this purpose.
3
3D view
The Hydrologic Engineering Center [1] (HEC) in Davis, in Davis, California developed California developed the River Analysis System (RAS) to aid hydraulic aid hydraulic engineers in channel flow analysis and floodplain determina determination tion.. It includ includes es numerous numerous data entry entry capabilities, hydraulic analysis components, data storage and management capabilities, capabilities, and graphing and reporting capabilities.
1
Advanta antage gess
HEC-RA HEC-RAS S has meri merits, ts, notab notably ly itssupport itssupport by theUS Army Army Corps of Engineer Engineers, s, the future future enhance enhancemen ments ts in progress progress,, and its acceptance by many government agencies and private firms. It is in the public domain and peer-reviewed, and avail availab able le to downl download oad free of charg chargee from rom HEC’s HEC’s web web site. Various Various private companies companies are registered registered as official official “vendors” and offer consulting support and add on software. Some also distribute the software in countries that are not permitted permitted to access access US Army web sites. sites. However, the direct download from HEC includes extensive documentation, documentation, and scientists scientists and engineers versed in hydraulic analysis should have little difficulty utilizing the software.
How How it works rks
The basic basic computati computational onal procedur proceduree of HEC-RAS HEC-RAS for for stea stead dy flow flow is base based d on the the sol soluti ution of the the oneonedimensi dimensional onal energy energy equatio equation. n. Energy Energy losses losses are evalua evaluated ted by friction and contraction / expansion. The momentum equation may be used in situations where the water surface profile is rapidly varied. These situations include hydraulic jumps, hydraulics of bridges, and evaluating profiles at river river confluences. confluences.
4
Disa Disad dvant vantag ages es
Users may find numerical numerical instability problems problems during unsteady steady analyse analyses, s, especi especiall ally y in steep steep and/or and/or highly highly dynamic dynamic rive rivers rs and strea streams. ms. It is often often possib possible le to use HECRAS to overcome instability issues on river problems. HEC-RAS is a 1-dimensional hydrodynamic model and
For unsteady flow, HEC-RAS solves the full, dynamic, 1-D Saint Venant Equation using Equation using an implicit, finite difference ference method. The unsteady flow equation solver solver was 1
2
8
will therefore not work well in environments that require multi-dimensional modeling. However, there are built-in features that can be used to approximate multidimensional hydraulics.
5
WMS (Watershed Modeling System) provides pre and post-processing tools for use with HEC-RAS. The development of WMS was funded primarily by The United States Army Corps of Engineers. Commercial licenses to WMS are available from the developer, Aquaveo LLC.[3] Features include:
HEC-RAS programs •
5.1
Aquaterra
Aquaterra is a professional software for canals and river engineering works design. Seamless integration in CAD environment makes it very easy to learn and use. Engineers use Aquaterra to create detailed designs as well as for conceptual studies and designs. HEC-RAS interface is intended for communication between CAD environment and HEC-RAS. This module prepares the HECRAS geometric input file based on cross sections, banks and Manning coefficient data and transfers the resulting water levels back to Aquaterra.
5.2
•
•
•
ArcView
HEC-RAS can also be used in the GIS program ArcView (With 3-D analyst and Spatial Analyst extensions). ArcView can read-in AutoCAD drawings for backgrounds and can create a Digital Terrain Model (DTM). In a similar way to river CAD, Geo-RAS can be used to create cross sections and other geometric data for use in HECRAS and can be used to export water surface data from HEC-RAS back into ArcView to create flood maps with depths and extents of flooding.
5.3
EXTERNAL LINKS
5.6 •
Edit, merge, and create cross sections in a database for use with HEC-RAS and other hydraulic models. Delineate flood plains from water surface elevation data. Water surface elevations can be computed by HEC-RAS, defined interactively, or imported from a file. Link multiple simulations of HEC-1 to HEC-RAS to determine the uncertainty in modeling parameters on a delineated flood plain. Curve Number and Precipitation can be stochastically varied among HEC-1 parameters and Manning’s n value for HECRAS.
HEC-Archives HEC-Archives by Dodson & Associates, Inc. [4]
(needed: other vendors’ products)
6
RAS
HEC-RAS has a dll library that allows you to create an application for use without a user interface. This dll proved to be useful for advanced analysis such as Monte Carlo uncertainty. The freeware application ARAS[2] takes advantage of such capability, and allows to automate several tasks like running several plans of updating roughness. “RAS” : River Analysis System
Use feature objects (centerline, cross section lines) and a TIN to develop the geometry of a HEC-RAS model.
See also •
Hydraulic Engineering
•
WMS (hydrology software)
•
MASCARET (Software)
7
References
[1] HEC.usace.army.mil
5.4
AutoCAD
[2] Hometss.com [3] Aquaveo.com
HEC-RAS can be used along with AutoCAD. A digital terrain model (DTM) can be constructed in AutoCAD and sections can be cut from the DTM and imported into HEC-RAS.
5.5
WMS (Watershed Modeling System)
Main article: WMS (hydrology software)
[4] a Dodson-hydro.com, free download site for archived versions of HEC-RAS and HEC-2]
8
External links •
Aquaterra River Design Software
•
WMS River Modeling Software
3
•
•
•
ISIS River Modelling Software Hydrologic Engineering Center - Institute for Water Resources - U.S. Army Corps of Engineers HEC-RAS home page at the US Army Corps of Engineers, Hydrologic Engineering Center
•
The RAS Solution - HEC-RAS help site
•
Hands-On HEC-RAS Seminar on CD by Dodson
•
•
•
An out put video of an flood analysis that done with HEC-RAS and visualizaten in ArcGIS Freeware applications that automates HEC-RAS features, such as creating geometry files, updating roughness and running several plans HEC-RAS Users Group on LinkedIn
4
9
9
TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES
Text and image sources, contributors, and licenses
9.1 •
9.2 •
Text HEC-RAS Source: https://en.wikipedia.org/wiki/HEC-RAS?oldid=642817293 Contributors: Hooperbloob, Woohookitty, Mandarax, MZMcBride, SmackBot, Gilliam, Mwtoews, Dumelow, Sepidar, MCalamari, Igoldste, Thijs!bot, MarshBot, Dudshan, Akmani, Jarvus lunt, Rainier5, Remember the dot, Maxim, Michael Frind, Toddst1, Joshschr, Alexbot, BOTarate, Robdb2, Mitch Ames, Addbot, DanReinders, Lotje, Dodson & Associates, Inc., El vladyman, BattyBot, Tadej Kodric, VT DLA, MaiTaro, Fzao and Anonymous: 32
Images File:Hydraulics-3Dview.jpg Source: https://upload.wikimedia.org/wikipedia/en/c/c0/Hydraulics-3Dview.jpg License: CC-BY-SA-3.0 Contributors: I Rainier5 created this work entirely by myself. Original artist:
Rainier5 •
File:Question_book-new.svg Source: https://upload.wikimedia.org/wikipedia/en/9/99/Question_book-new.svg License: Cc-by-sa-3.0 Contributors: Created from scratch in Adobe Illustrator. Based on Image:Question book.png created by User:Equazcion Original artist: Tkgd2007
9.3 •
Content license Creative Commons Attribution-Share Alike 3.0
