ASTM_D_5243_-_92_2013.pdf

Designation:D524392(Reapproved 2013)Standard Test Method forOpen-Channel Flow Measurement of Water Indirectly atCulverts1This standard is issued under the fixed designation D5243;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the computation of discharge(the volume rate of flow)of water in open channels or streamsusing culverts as metering devices.In general,this test methoddoes not apply to culverts with drop inlets,and applies only toa limited degree to culverts with tapered inlets.Informationrelated to this test method can be found in ISO 748 and ISO1070.1.2 This test method produces the discharge for a floodevent if high-water marks are used.However,a completestage-discharge relation may be obtained,either manually orby using a computer program,for a gauge located at theapproach section to a culvert.1.3 The values stated in inch-pound units are to be regardedas the standard.The SI units given in parentheses are forinformation only.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3858 Test Method for Open-Channel Flow Measurementof Water by Velocity-Area Method2.2 ISO Standards:3ISO 748 Liquid Flow Measurements in Open Channels-Velocity-Area MethodsISO 1070 Liquid Flow Measurements in Open Channels-Slope-Area Methods3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1129.3.2 Several of the following terms are illustrated in Fig.1.3.3 Definitions of Terms Specific to This Standard:3.3.1 alpha()a velocity-head coefficient that adjusts thevelocity head computed on basis of the mean velocity to thetrue velocity head.It is assumed equal to 1.0 if the cross sectionis not subdivided.3.3.2 conveyance(K)a measure of the carrying capacity ofa channel and having dimensions of cubic feet per second.3.3.2.1 DiscussionConveyance is computed as follows:K 51.486nR2/3Awhere:n=the Manning roughness coefficient,A=the cross section area,in ft2(m2),andR=the hydraulic radius,in ft(m).3.3.3 cross sections(numbered consecutively in down-stream order):3.3.3.1 The approach section,Section 1,is located oneculvert width upstream from the culvert entrance.3.3.3.2 Cross Sections 2 and 3 are located at the culvertentrance and the culvert outlet,respectively.3.3.3.3 Subscripts are used with symbols that representcross sectional properties to indicate the section to which theproperty applies.For example,A1is the area of Section 1.Items that apply to a reach between two sections are identifiedby subscripts indicating both sections.For example,hf12is thefriction loss between Sections 1 and 2.1This test method is under the jurisdiction of ASTM Committee D19 onWaterand is the direct responsibility of Subcommittee D19.07 on Sediments,Geomorphology,and Open-Channel Flow.Current edition approved Jan.1,2013.Published January 2013.Originallyapproved in 1992.Last previous edition approved in 2007 as D5243 92(2007).DOI:10.1520/D5243-92R13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.3.4 cross sectional area(A)the area occupied by thewater.3.3.5 energy loss(hf)the loss due to boundary frictionbetween two locations.3.3.5.1 DiscussionEnergy loss is computed as follows:hf5 LSQ2K1K2Dwhere:Q=the discharge in ft3/s(m3/s),andL=the culvert length in ft(m).3.3.6 Froude number(F)an index to the state of flow inthe channel.In a rectangular channel,the flow is subcritical ifthe Froude number is less than 1.0,and is supercritical if it isgreater than 1.0.3.3.6.1 DiscussionThe Froude number is computed asfollows:F 5V=gdmwhere:V=the mean velocity in the cross section,ft/s(m/s),dm=the average depth in the cross section,in ft(m),andg=the acceleration due to gravity(32 ft/s2)(9.8 m/s2).3.3.7 high-water marksindications of the highest stagereached by water including,but not limited to,debris,stains,foam lines,and scour marks.3.3.8 hydraulic radius(R)the area of a cross section orsubsection divided by the wetted perimeter