WinDAM B Earthen Embankment Overtopping Analysis Software

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WinDAM B Earthen Embankment Overtopping Analysis Software

WinDAM B EarthenEmbankment OvertoppingAnalysis SoftwareKarl Visser, PEHydraulic EngineerFort Worth, TXNatural Resources Conservation ServiceNat’l Design Construction & Soil Mechanics Center


Co-AuthorsARS – Stillwater, OK• Dr. Gregory Hanson, Retired• Dr. Darrel Temple, Retired• Ronald Tejral, Ag EngineerKSU – Manhattan, KS• Dr. Mitchell NeilsenFeb 2013 FEMA NDS 20 - WinDAM B Software 2


What does WinDAM Bdo?Why would I use it?


WinDAM B Capability• Hydraulics• Route 1 hydrograph through 1 dam• Estimate erosion• 1-3 earth or vegetated aux spillways• Overtopping erosion of earthenembankmentFeb 2013 FEMA NDS 20 - WinDAM B Software 5


Overtopping Erosion• Earthen embankment• Homogenous fill, not zoned• Slope protection• Bare soil• Grass• RiprapFeb 2013 FEMA NDS 20 - WinDAM B Software 6


Hydrology• User-supplied hydrograph• 1 input hydrograph per runFeb 2013 FEMA NDS 20 - WinDAM B Software 7


Hydraulics• 1 hydrograph routed• 1 dam• Principal spwy• Aux spwys (veg or earth)• OvertoppingFeb 2013 FEMA NDS 20 - WinDAM B Software 8


Tailwater Rating TableTailwater f(Outflow)Tailwater f(Outflow)Feb 2013 FEMA NDS 20 - WinDAM B Software 9


Aux Spillway Erosion• 0, 1, 2, or 3 auxiliary spillways• Vegetated or earthenDamFeb 2013 FEMA NDS 20 - WinDAM B Software 10


WinDAM VersionsWinDAM A+WinDAM BWinDAM C(proposed)WinDAM D(proposed)WinDAM E(proposed)Overtopping analysis(Slope protection evaluation)Homogenous embankmentovertopping & erosion analysisInternal erosion (piping)homogenous fill embankmentPotential failure initiation @ toe/berms/groinsAlternative embankment slope protection(ACB’s, reinforced vegetation)Zoned fill embankment overtopping erosionFeb 2013 FEMA NDS 20 - WinDAM B Software 11


Erosion & HydraulicsAuxiliary SpillwayEstimates 2D erosionof weakest unit widthAux spillway flowunaffected by erosionHydraulics & aux spwyerosion – not coupledEmbankmentOvertoppingEstimates 3D erosion ofhomogenous earthfillLateral widening &deepening headcuterosion increases outflowHydraulics & embankmenterosion coupledFeb 2013 FEMA NDS 20 - WinDAM B Software 12


Aux Spwy Erosion -2D EstimateGeologic materials,naturally formed &weathered, variedUnit WidthAug 2012 WinDAM B Purpose & Policy 13


Embankment Erosion -3D EstimateHomogenousengineered earth fill,uniform propertiesAug 2012 WinDAM B Purpose & Policy14


Download WinDAM B?1. http://go.usa.gov/8Oq2. http://www.damsafety.info/3. Search for“NRCS WinDAM download”Feb 2013 FEMA NDS 20 - WinDAM B Software 15


WinDAM B Input


WinDAM B InputsPrincipal spillwayInflow hydrographsAuxiliary spillway(s)Analysis MethodsDam crest embankmentFeb 2013 FEMA NDS 20 - WinDAM B Software 17


Input Screens• Project Information• Model Properties• Dam SurfaceDescription• Structure Table• Hydrograph DataTable• Principal SpillwayType• Tailwater RatingTable• Aux Spillways• Aux Spwy RatingTable: #• Aux SpwyProperties: #• Headcut ModelFeb 2013 FEMA NDS 20 - WinDAM B Software 18


Geotechnical Input forEmbankment ErosionTemple/HansonEnergy ModelErodibilityCritical shear stressAdvance ratecoefficientHanson/RobinsonStress ModelErodibilityCritical shear stressUndrained shearstrengthTotal unit weightFeb 2013 FEMA NDS 20 - WinDAM B Software 19


Output


Outputs• Breach & Dam• Emb Headcut• Hydrographs & Resv• Overtopping• Tailwater & RatingsFeb 2013 FEMA NDS 20 - WinDAM B Software 21


Output Types1) Summary Table2) Graphical Plots3) Text Output• Dam embankment - overtopping• Aux Spillway 1• Aux Spillway 2• Aux Spillway 3Feb 2013FEMA NDS 20 - WinDAM B Software 22


Summary TableViewSummary TblFeb 2013FEMA NDS 20 - WinDAM B Software 23


Summary Tbl EntriesInput Data Flow DamPS/AS Crest Peak Total RCI - Veg CoverTop of Dam Peak PS/AS Maintenance CodeLength of Dam Peak Overtop/Breach Max Gross Hydrograph Label Max Overtop Depth % Allowable Gross Peak Inflow Overtop Duration % Allowable Eff Start Routing Elev Max Overtop/Breach q % Allowable Unit qFeb 2013FEMA NDS 20 - WinDAM B Software 24


Summary Tbl Entries(cont’d)BreachSlope Prot. Failure T Breach Init. TDam Breach Model Breach formation TFill Total Unit Weight Final Breach WidthFill Erodibility # ErrorsUndrained Shear # WarningsCritical Shear Fill Advance Rate CoeffFeb 2013FEMA NDS 20 - WinDAM B Software 25


Plots: DamFeb 2013FEMA NDS 20 - WinDAM B Software 26


Headcut/Breach WidthHow wide isembankmentbreach duringevent?Feb 2013FEMA NDS 20 - WinDAM B Software 27


Dam Cross SectionWhat is dam crosssection?Feb 2013FEMA NDS 20 - WinDAM B Software 28


Dam Crest ProfileWhat is elevation of dam crestbetween abutments?Feb 2013FEMA NDS 20 - WinDAM B Software 29


Headcut AdvanceDam X-secHeadcut PositionSoil SurfacePlan viewHeadcut WidthFeb 2013HrsTime sliderFEMA NDS 20 - WinDAM B Software 30


Headcut PositionWhere is upstreamedge of breach?Feb 2013FEMA NDS 20 - WinDAM B Software 31


Max Overtop/BreachUnit Discharge (cfs/ft)What is unitovertoppingflow?Feb 2013FEMA NDS 20 - WinDAM B Software 32


Max Overtop HeadHow deep isovertoppingflow?Feb 2013FEMA NDS 20 - WinDAM B Software 33


Overtopping Stress% Allowable 100% AllowErosionWhen doessurfaceprotection fail?Gross veg & soilEff – soil onlyFeb 2013FEMA NDS 20 - WinDAM B Software 34


Plots – Aux Spwy• Geology• Erosion Max/Mean/Min• Hydrograph• Spillway Rating• Rate Equations• Threshold EquationsFeb 2013FEMA NDS 20 - WinDAM B Software 35


Text Output• Dam• WinDAM output• Breach Progression Table• Breach Details• Auxiliary spillway 1/2/3• Spillway outputFeb 2013FEMA NDS 20 - WinDAM B Software 37


Dam: WinDAM Output• Input data• Warnings• Summary output• Stress on Embankment Slope• Hydraulic Routing Detail Table• Spillway and Overtop Discharge Rating• Listing of Tabular Data-Expanded VolFeb 2013FEMA NDS 20 - WinDAM B Software 38


Dam:Breach Progress TblFeb 2013FEMA NDS 20 - WinDAM B Software 39


Dam: Breach DetailsFeb 2013FEMA NDS 20 - WinDAM B Software 40


Aux Spwy: Spwy Output• Aux spwy flow hyd• Aux spwy inputs• Profile• Materials• Surface Conditions Summary by Reach• Integrity Analysis• Reach Surface Performance Summary• Headcut Erosion Damage SummaryFeb 2013FEMA NDS 20 - WinDAM B Software 41


Does NRCS allow damovertopping?


NRCS Allow Overtopping?• NRCS Policy -TR-60• Overtopping duringdesign stormnot allowed• WinDAM B• Technical tool• Not policy• Examine “what if”Feb 2013 FEMA NDS 20 - WinDAM B Software 43


Use WinDAM BOvertopping for . . .Prioritize dam rehab projectsBreach analysis - emergencyaction plansHazard class - existing damsNew design & rehab designs(designed overtopping)Feb 2013 FEMA NDS 20 - WinDAM B Software 44


How can I prioritizedam safety rehabprojects?


AvailablefundingDam SafetyRehabilitationProject NeedsFeb 2013 FEMA NDS 20 - WinDAM B Software 46


Potential OvertoppingDamage AssessmentInflow hydrograph(e.g. WinTR‐20/HEC‐HMS)OvertoppingoutflowhydrographWinDAM BEstimatedownstreamdamages (affectedpeople &structures)Hydraulic routingdownstream(e.g. HEC‐RAS)Feb 2013 FEMA NDS 20 - WinDAM B Software 47


Greatest OvertoppingDamageFeb 2013 FEMA NDS 20 - WinDAM B Software 48


Overtopping Basics• What qualitative answers shouldI expect from WinDAM B?• How can I check forreasonableness?Feb 2013 FEMA NDS 20 - WinDAM B Software 49


Dam Height vs ErosionErosionDam HeightFeb 2013 FEMA NDS 20 - WinDAM B Software 50


Stored Volume vs ErosionErosionStored VolumeFeb 2013 FEMA NDS 20 - WinDAM B Software 51


Overtopping Duration vsErosionErosionOvertopping DurationFeb 2013 FEMA NDS 20 - WinDAM B Software 52


Drainage Area vs ErosionErosionDrainage AreaFeb 2013 FEMA NDS 20 - WinDAM B Software 53


Cohesiveness vs ErosionErosionNon-cohesiveembankmentCohesiveembankmentFeb 2013 FEMA NDS 20 - WinDAM B Software 54


Factors that increaseerosion• Higher dam height• Greater stored volume• Longer overtopping duration• Larger drainage area• More erodible embankment materialFeb 2013 FEMA NDS 20 - WinDAM B Software 55


WinDAM B Results• Erosion Estimate• Suite of answers vs “the answer”• Order of magnitude - inputsFeb 2013 FEMA NDS 20 - WinDAM B Software 56


Corps of EngineersCorps of EngineersLevees & CanalsCan I use WinDAM B for levee andcanal overtopping?Feb 2013 FEMA NDS 20 - WinDAM B Software 57


WinDAM B Limitations –Levees & Canals• No internal erosion• No seepage/underflow component• No erosion estimate at levee toe (justbackslope of embankment)• Modify inflow hydrograph/capacitytable to model river stageFeb 2013 FEMA NDS 20 - WinDAM B Software 58


Questions?ND National Guard – Lake LaMoure 2009Feb 2013 FEMA NDS 20 - WinDAM B Software 59

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