NRCS has adopted the Corps of Engineer's HecRas (River Analysis System) for computation of water surface profiles. Use of the NRCS program WSP2 has been phased out as NRCS engineers become trained and experienced with HecRAS. The major advantage of this program are Windows-based graphics for input and output, program technical and financial support at the Corps of Engineers Hydrologic Engineering Center, future enhancements expected, and its use by other government agencies and private engineers.
HecRAS program download
Visit the Corps of Engineers website: Hydrologic Engineering Center.
NRCS Empoyees take note: Your government computers require a CCE version which may be obtained from your IT support staff.
The HecRAS package includes several support documents, pdf files that are accessible from the program's main user interface. Separate copies may be downloaded here:
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HecRAS User's Manual is a guide to using HecRAS. The 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.
HecRAS Hydraulic Reference Manual describes the theory and data requirements for hydraulic calculations performed by HecRAS. Equations are presented along with the assumptions used in their derivation. Discussions are provided on how to estimate model parameters, as well as guidelines on various modeling approaches.
HecRAS Applications Guide contains a series of examples that demonstrate various aspects of HecRAS. Each example consists of a problem statement, data requirements, general outline of solution steps, displays of key input and output screens, and discussions of important modeling aspects.
WRAS is a conversion program developed by NRCS that takes existing WSP2 data sets and converts them in HecRAS format for import into HecRAS. Users should be aware that significant differences exist between HecRAS and WSP2 as to the way topography is represented by cross-sections. Users are urged to become fully informed of all differences between the two models by reading the user manuals.
WRAS is written in Visual Basic 6.0, and requires Windows 95 or higher. WRAS is CCE compatible, but also runs on non-CCE machines.
Download Version 1.1, dated 1/27/2004
TR-20 Rating Table Program
One reason for computing water surface profiles is to develop cross section rating tables used in the NRCS TR-20 program for flood routing of stream reaches. The WSP2 program developed these tables as an option. However, HecRAS does not automatically develop there tables in the correct format for TR-20. For this reason, a program (named Rating_Table.exe) was written by NRCS to take a HecRAS output file and develop rating tables formatted for input to TR-20. HecRAS has many optional output variables and allows the user to develop a customized table with certain desired information. This customized table, once created and saved, will be accessible for use whenever HecRAS is run on the various projects and plans organized by the user. The program was written based on output from HecRAS version 2.2. Download the zipped file Rating.zip.
Introduction to HecRAS Course
The introductory training course is designed for engineers with some knowledge of basic hydraulic principles and no prior experience with HecRAS. It was developed by NRCS as a three-day course and has been presented in several classroom settings. The materials may also be used for self-training. The Power Point presentations include views of various HecRAS data input screens and the examples include actual data for hands-on experience.
These files require a zip utility or Powerpoint.
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Download Overview (10 mb)
Download Water Surface Profiles (4 mb)
Download Basic Input (10 mb)
Download Bridges (11 mb)
Download Culverts (4 mb)
Download Other Features Part 1 (6 mb)
Download Other Features Part 2 (1.8 mb)
Download Junctions (1.4 mb)
Download Drop Structures (1.6 mb)
Download Inline Weirs (463 kb)
Download Trouble Shooting (1.1 mb)
Download Intro to Unsteady Flow (1.3 mb)
NRCS employees and conservation partners may contact the NRCS HecRAS Team with questions or to obtain further information. Email the HecRas Team.
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