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WinDAM C Software

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Estimating Erosion of Earthen Embankments and Auxiliary Spillways of Dams

piping failure photo of water over spillway

Q:  What is the purpose of WinDAM C software?

A:    WinDAM C  models erosion in earthen embankments as well as erosion in earthen auxiliary spillways of dams. The three-phase erosion model 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 development of concentrated flow.

2)    Phase two is downward erosion in the area of concentrated flow, resulting in headcut formation.

3)    Phase three is downward and upstream movement of the headcut, potentially breaching the spillway or embankment.

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.

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Q:  Where can I download WinDAM C software?

              A. click here: download button   for WinDAMC

Q:  Where can I download WinDAM C manuals?

             A. click here: download button    for zipped file

Q:  How do I start using WinDAM C?

A:    Here are steps to start using WinDAM C and viewing example input files:

1)    Download WinDAM C software and WinDAM C example files
        Install WinDAM C software.
        Then unzip the WinDAM C example files onto your computer.

2)    Run WinDAMC.exe.
        Picture of earth dam and reservoir appears.
        Screen title is: WinDAM C

3)    Create a new project directory for the WinDAM C input examples.
        (File-->New Project--> browse and type in a new project name)

4)    Import unzipped *.wdc example input files into the newly-created WinDAM C project.
        (File-->Import File-->  browse and select *.wdc example input files)

5)    Run the example files now located in the WinDAM C project directory.
        (Run-->Simulate All Files)  

6)    View the example files output summary in WinDAM C.
        (View-->Summary Table)

7)    To view graphs or additional text output of the example output:
        Left-click a filename in summary table.
        Column becomes highlighted in blue.
        Click bottom-row buttons to View Graphs/View Text/View Aux Spillway #.

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Q: Where can I download some example data sets?
        A:  Fifteen sample data sets, combined in one download file, demonstrate some of the WinDAM C features.
                    They are described in the table below the download button.

                click here: download button    for
WinDAM C Example Filename Example File Description
   01-PSwDD.WDC  Principal spillway routing with drawdown
   02-SDHstability.WDC  Earth spillway stability or integrity design
   03-TH-Overtop.WDC  Embankment overtopped, but not breached, Maintenance Code 1, Temple/Hanson energy model
   04-HR-Overtop.WDC  Embankment overtopped, but not breached, Maintenance Code 1, Hanson/Robinson stress model
   05-HR-OvertopBreach.WDC  Embankment overtops & breaches, Maintenance Code 3, Hanson/Robinson
   stress model
   06-HR-OvertopBreach.WDC  Embankment overtops & breaches, Maintenance Code 3, Temple/Hanson
   energy model
   07-FBIntegrity.WDC  Integrity Design, Maintenance Code 2
   08-FBIntegritywBarrier.WDC  Integrity Design, Maintenance Code 2
 Integrity design, no barrier, sandy auxiliary spillway (RTside) breaches.
  Auxiliary spillway BREACH halts auxiliary spillway erosion computations,
  however, hydraulic computations continue.
   10-FBIntegrity2AuxSpwy.WDC  Stability/integrity design, two auxiliary spillways
 Stability/integrity design, two auxiliary spillways, tailwater added
   12-FBIntegrity2AS1Structural.WDC  Two auxiliary spillways, one auxiliary spillway is a structural spillway
   13-IE-slowKd005.WDC   Internal erosion, low erodibility (Kd = 0.05 ft/hr/psf)
   14-IE-medKd050.WDC   Internal erosion, medium erodibility (Kd = 0.50 ft/hr/psf)
   15-IE-fastKd500.WDC   Internal erosion, high erodibility (Kd = 5 ft/hr/psf)

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Q:  What hydrology methods are included in WinDAM C?

A:    WinDAM C does not create a reservoir inflow hydrographs.  The reservoir inflow hydrograph must be created outside of WinDAM B and imported or pasted into the input screen.  Software from NRCS such as SITES or WinTR-20 can create the needed hydrograph.  Software from other agencies or vendors such as Corps of Engineers HEC-HMS can also be used to create the reservoir inflow hydrograph.

WinDAM C hydraulically routes a single inflow hydrograph through the dam’s riser/conduit, auxiliary spillway, and over the embankment to create an outflow hydrograph.

Q:  How is WinDAM C different from SITES software?

A:    WinDAM C software does not check the design for compliance with NRCS design criteria.  The user must check the design.  WinDAM C estimates the erosion in an earthen auxiliary spillway as well as the erosion from overtopping the earthen embankment.  WinDAM C does not create a reservoir inflow hydrograph, it only imports an existing hydrograph. SITES software checks the site design against existing USDA-NRCS design criteria found in USDA-NRCS National Engineering Handbook Part 630 – Hydrology, Technical Release 60, and National Conservation Practice Standard 378 – Pond.  SITES software estimates erosion in an earthen auxiliary spillway, but does not analyze embankment overtopping.  SITES can create a hydrograph from basic hydrologic information such as: rainfall depth, rainfall distribution, rainfall duration, drainage area, and runoff curve number.

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Q:  Will WinDAM C replace SITES?

A:    No, WinDAM C will not replace SITES.  New features will continue to be added to the WinDAM series.  SITES will be maintained (though not enhanced) as a design tool for NRCS engineers and others who want to use it.

Q:  Who created WinDAM C software?

A:    WinDAM C was developed cooperatively by US Department of Agriculture-Agricultural Research Service, USDA-Natural Resources Conservation Service, and Kansas State University.

Q:  What kind of geotechnical information do I need for a WinDAM C analysis?

A:    For a complete erosion estimate including the auxiliary spillway and earthen embankment, the geotechnical composition of these two features of the dam must be characterized.  Typical parameters such as representative particle size, percent clay fraction, plasticity index, total unit weight, undrained shear strength, and critical shear stress.  Specific to WinDAM C software, the headcut erodibility index (Kh) and detachment coefficient (Kd) also need to be estimated. 

Q:  What fees or licensing is required to use WinDAM C software?

A:    None.  The Natural Resources Conservation Service, the Agricultural Research Service, and Kansas State University used government funds to develop the WinDAM C software. It may be downloaded for use and copying at no additional expense or license requirements.

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Q:  Who can I contact for additional information about WinDAM C software?

A: These NRCS employees can help answer your questions:

    Gregg Hudson, Geologist     817/509-3761
    Karl Visser, Hydraulic Engineer     817/509-3763

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Q:  What is the current version WinDAM C?

A:    Version 1.1.12 was released May 2021.

Q:  My earth embankment dam doesn’t have grass growing on it.  Can I still use WinDAM C software?

A:    WinDAM C can estimate erosion if the dam slope is protected by vegetation, riprap, or is simply bare earth.  WinDAM C does not handle other erosion protection measures such as articulated concrete blocks (ACB’s) or erosion matting products.

Q:  I want to analyze internal erosion (piping) of my dam.  Can I use WinDAM C software?

A:    Yes.  WinDAM C has the capability to analyze internal erosion through an earthen embankment, as well as overtopping erosion.

Q:  WinDAM C software analyzes dam overtopping flows.  Does NRCS policy allow overtopping?

A:    WinDAM C earthen embankment overtopping software and manuals do not contain NRCS policy regarding NRCS design for dams and ponds. However, policy regarding NRCS dam design and dam safety is contained in the following documents:

WinDAM C software is a useful tool for prioritizing dam rehabilitation projects for existing dams. WinDAM C software can also be used to design dams to comply with NRCS policy.

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