ASTM_D_5130_-_95_2014.pdf

Designation:D513095(Reapproved 2014)Standard Test Method forOpen-Channel Flow Measurement of Water Indirectly bySlope-Area Method1This standard is issued under the fixed designation D5130;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 representative cross-sectional characteristics,the water-surface slope,and coefficient of channel roughness as input togradually-varied flow computations.2,31.2 This test method produces an indirect measurement ofthe maximum discharge for one flow event,usually a specificflood.The computed discharge may be used to help define thehigh-water segment of a stage-discharge relation.1.3 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.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:4D1129 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:5ISO 748 Liquid Flow Measurements in Open ChannelsVelocity-Area MethodISO 1070 Liquid Flow Measurements in Open ChannelsSlope-Area Method3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 Several of the following terms are illustrated in Fig.1:3.2.2 alpha()a velocity-head coefficient that representsthe ratio of the true velocity head to the velocity headcomputed on the basis of the mean velocity.It is assumed equalto 1.0 if the cross section is not subdivided.For subdividedsections,is computed as follows:5(Ski3Ai2DKT3AT2where:K and A=the conveyance and area of the subsectionindicated by the subscript i,andKTand AT=the conveyance and area of the entire crosssection.3.2.3 conveyance(K)a measure of the carrying capacity ofa channel and has dimensions of cubic feet per second or cubicmetres per second.Conveyance is computed as follows:K 51.486nAR2/3where:n=the Manning roughness coefficient,A=the cross-section area,ft2(m2),andR=the hydraulic radius,ft(m).NOTE11.486=1.00 SI unit.3.2.4 cross sections(numbered consecutively in downstreamorder)representative of a reach of channel and are positioned1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.07 on Sediments,Geomorphology,and Open-Channel Flow.Current edition approved Jan.1,2014.Published March 2014.Originallyapproved in 1990.Last previous edition approved in 2008 as D5130 95(2008).DOI:10.1520/D5130-95R14.2This test method is similar to methods developed by the U.S.GeologicalSurvey and described in Refs(1-3).33The boldface numbers in parentheses refer to a list of references at the end ofthis standard.4For 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.5Available 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 as nearly as possible at right angles to the direction of flow.They must be defined by coordinates of horizontal distance andground elevation.Sufficient ground points must be obtained sothat straight-line connection of the coordinates will adequatelydescribe the cross-section geometry.If major breaks in thehigh-water profile are evident,cross sections should be locatedat the breaks.3.2.5 cross-section area(A)the area of the water belowthe high-water surface elevations that are computed by assum-ing a straight-line interpolation between elevations on eachbank.The area is computed as the summation of the productsof mean depth multiplied by the width between stations of thecross section.3.2.6 friction loss(hf)the loss due to boundary friction inthe reach and is equivalent to the following:h1hv2 khv!where:h=the fall in the reach,hv=the upstream velocity head minus the downstreamvelocity head,(khv)=the energy loss due to acceleration or decelerationand to eddies in a contracting or expanding re