Earthen/Vegetated Auxiliary Spillway Erosion Prediction for Dams
(version 2005.1.6) short url for this page: http://go.usa.gov/83z
NOTE: If Version 2005.1.5 is installed, it must be uninstalled. Version 2005.1.5 should not be used, due to errors in routing of long duration drawdowns.
The Natural Resources Conservation Service, the Agricultural Research Service, and Kansas State University used government funds to develop the Water Resources Site Analysis Program (SITES) computer program. It may be downloaded for use and copying at no additional expense or license requirements.
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History SITES User Guide Erosion Technology
Program Purpose Design Guidance Contact NRCS
Features Example Data Downloads
Integrated Development Training Materials Version 2005.1.6
The SITES software is a descendent of the DAMS2 program, a full-featured rainfall-runoff routing program developed for watershed dam design and analysis. In developing the SITES software, DAMS2 was recoded and the auxiliary (emergency) spillway analysis portion of the program was expanded to include technology developed for spillway performance evaluation through the joint efforts of the Agricultural Research Service (ARS) and the NRCS. The Integrated Development Environment (IDE) for the SITES software was developed cooperatively by NRCS, ARS, and Kansas State University. The SITES computer program can be used for both TR-60 watershed dams and 378 CO-01 dams.
SITES models erosion in earthen and vegetated auxiliary spillways of dams. The three-phase erosion model that SITES uses was jointly developed by the Agricultural Research Service (ARS) and the NRCS.
1) Phase one of the erosion or failure process is failure of the vegetal cover and
the development of concentrated flow.
2) Phase two is downward erosion in the area of concentrated flow, resulting in
3) Phase three is downward and upstream movement of the headcut, potentially
breaching the spillway.
Each phase is described by a set of threshold-rate relationships based on the process mechanics. A headcut erodibility index (Kh) describes the resistance of the exposed geologic materials to erosive attack during the third phase of the process. Aids for estimating this index are included in help screens and in supporting materials discussed below.
The Sites software has great flexibility in developing the auxiliary spillway rating and evaluating exit channel stability. SITES accepts vegetal retardance potential for flow resistance input as well as Manning's n, and flow resistance can vary from reach to reach in the spillway. SITES develops a spillway rating for subcritical exit channel flow. For both supercritical and subcritical flows, SITES evaluates exit channel stability using the allowable tractive stress approach.
When applied in design, the earth spillway erosion model incorporated into SITES is normally used to evaluate the potential for spillway breach under a freeboard hydrograph having at least 24 hours rainfall duration. Evaluation of the potential for extending the model for use in predicting breach rates is presently underway.
SITES Integrated Development Environment (IDE)
NRCS, ARS, and Kansas State University cooperatively developed the SITES IDE. SITES software (7.3 Mb) includes the IDE with help for input and output screens. The interface handles sites in series, but primarily analyzes the most downstream structure. SITES runs in Windows 98SE/2000/ NT/XP/Vista/Windows 7 operating systems (version 2000 or later recommended). Minimum recommend RAM is 32 Mb.
The IDE user interface guides the user through data input screens and output interpretation. Output includes a customizable summary table and graphical output showing hydrologic, structural, and hydraulic parameters. The IDE handles complex watersheds with upstream structures, sub-watersheds, and channel reaches through a watershed schematic screen.
SITES User Guide
The SITES User Guide (34.8 Mb) package contains SITES Water Resource Site Analysis Computer Program User’s Guide (210-9-8) documenting the capabilities and I/O requirements. Appendix A is a Quick Start guide for beginning users. The User's Guide describes use of the software through the integrated development environment as well as providing information to allow advanced users to access extended capabilities of the computational routine.
The design guidance package (3.7 Mb) contains Chapters 50, 51, and 52 of NRCS NEH 628, TR-60, and NHCP-378. Chapters 50, 51, and 52 of NRCS NEH-628 contain auxiliary spillway layout and design guidance, details of the auxiliary spillway performance model, and procedures for estimating the headcut erodibility index, respectively. TR-60 and NHCP-378 describe NRCS design criteria and are essential references for development of input data for application of SITES. A spreadsheet is available to assist in calculating the Headcut Erodibility Index, khcalc.xls, (also in the design guidance package). Instructions for its use are contained within the spreadsheet itself and on pages 31-33 of NEH-628 Chapter 52 of the design guidance package.
The example data package (15 Kb) includes example data for testing and becoming familiar with SITES. Data sets with the D2C extension may be imported into the IDE. Data sets with the DAT extension illustrate the extended capabilities of the computational routine for advanced users. These sample data sets are discussed in Appendix C of the SITES Water Resource Site Analysis Computer Program User’s Guide. The data sets were developed to illustrate program features only, and do not represent any real sites or conditions.
The training and tutorial package (20.9 Mb) contains Power Point® presentations and notes that may be used for training or as a self-study tutorial. These presentations were originally developed to train NRCS engineers and geologists in the use of the SITES software. A background in hydraulics and erosion mechanics is assumed. This package was developed for earlier versions of SITES and discussions may not reflect all capabilities of SITES 2005.
More Spillway Erosion Technology Information
The user is responsible to understand the complex spillway erosion processes, input variables required by the model, and the applicability of the model to design conditions. Publications documenting the underlying spillway erosion technology are available through the USDA ARS Hydraulic Engineering Research Unit in Stillwater, OK.
Karl Visser (ph: 817-509-3763 email: Karl.Visser@ftw.usda.gov)
Helen Fox Moody (301-504-3948 email: email@example.com)
SITES 2005 (version 2005.1.6) (7 Mb)
Sites 2005 Users Guide
Dam and Spillway Design Guidance Package (4 Mb)
Example Data (15 Kb)
Training/Tutorial Materials (21 Mb)
The use of trade names does not constitute endorsement by the developers or by the USDA.
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