Designation:D5243−92(Reapproved2013)StandardTestMethodforOpen-ChannelFlowMeasurementofWaterIndirectlyatCulverts1ThisstandardisissuedunderthefixeddesignationD5243;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthecomputationofdischarge(thevolumerateofflow)ofwaterinopenchannelsorstreamsusingculvertsasmeteringdevices.Ingeneral,thistestmethoddoesnotapplytoculvertswithdropinlets,andappliesonlytoalimiteddegreetoculvertswithtaperedinlets.InformationrelatedtothistestmethodcanbefoundinISO748andISO1070.1.2Thistestmethodproducesthedischargeforafloodeventifhigh-watermarksareused.However,acompletestage-dischargerelationmaybeobtained,eithermanuallyorbyusingacomputerprogram,foragaugelocatedattheapproachsectiontoaculvert.1.3Thevaluesstatedininch-poundunitsaretoberegardedasthestandard.TheSIunitsgiveninparenthesesareforinformationonly.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D1129TerminologyRelatingtoWaterD2777PracticeforDeterminationofPrecisionandBiasofApplicableTestMethodsofCommitteeD19onWaterD3858TestMethodforOpen-ChannelFlowMeasurementofWaterbyVelocity-AreaMethod2.2ISOStandards:3ISO748LiquidFlowMeasurementsinOpenChannels-Velocity-AreaMethodsISO1070LiquidFlowMeasurementsinOpenChannels-Slope-AreaMethods3.Terminology3.1Definitions—Fordefinitionsoftermsusedinthistestmethod,refertoTerminologyD1129.3.2SeveralofthefollowingtermsareillustratedinFig.1.3.3DefinitionsofTermsSpecifictoThisStandard:3.3.1alpha(α)—avelocity-headcoefficientthatadjuststhevelocityheadcomputedonbasisofthemeanvelocitytothetruevelocityhead...
