ASTM_D_4410_-_16.pdf

Designation:D441016Terminology forFluvial Sediment1This standard is issued under the fixed designation D4410;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 These terms are to be used by persons involved incollecting,reporting,and interpreting information pertaining tosedimentation and hydrologic processes as they apply in thedevelopment,use,control,and conservation of water and landresources.1.2 Some listed terms and definitions are from other ASTMstandards and the source document is given in bold type at theend of the definition.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.2.Referenced Documents2.1 ASTM Standards:2D5614 Test Method for Open Channel Flow Measurementof Water with Broad-Crested WeirsD5640 Guide for Selection of Weirs and Flumes for Open-Channel Flow Measurement of WaterD5674 Guide for Operation of a Gaging StationD6855 Test Method for Determination of Turbidity Below 5NTU in Static ModeD6698 Test Method for On-Line Measurement of TurbidityBelow 5 NTU in WaterD7937 Test Method for In-situ Determination of TurbidityAbove 1 Turbidity Unit(TU)in Surface Water3.Terminology3.1 Terms and Definitions:accelerated erosion,nerosion at a rate greater than geologicor natural erosion.DISCUSSIONAccelerated erosion is usually associated with anthro-pogenic activities and usually reduces plant cover and increases runoff.accretion,na process of sediment accumulation.agglomeration or flocculation,nthe coalescence of dis-persed suspended matter into large flocs or particles whichsettle rapidly.aggradation,nthe geologic process by which stream beds,flood plains,and the bottoms of other water bodies are raisedin elevation by the deposition of material eroded andtransported by water from other areas.alluvial channel,nsee alluvial stream.alluvial deposit,nsediment deposited by the action ofmoving water.alluvial fans,nsediment deposited in the shape of a segmentof a cone formed because of a sudden flattening of a streamgradient especially at debouchures of tributaries on mainstream flood plains.alluvial stream,na stream whose boundary is composed ofappreciable quantities of the sediments transported by theflow and which generally changes its bed forms as the rate offlow changes.alluviation,nthe process of accumulating sediment depositsat places where the flow is retarded.alluvium,na general term for all fluvial deposits resultingdirectly or indirectly from the sediment transport of(mod-ern)streams,thus including the sediments laid down inriverbeds,flood plains,lakes,fans,and estuaries.ambient light,nlight or optical path or both that does notoriginate from the light source of a turbidimeter.D7937antidunes,nbed forms that occur at a velocity higher thanthat velocity which forms dunes and plane beds.DISCUSSIONAntidunes commonly move upstream,and are accom-panied by,and in phase with,waves on the water surface.armoring,nthe formation of a resistant layer of relativelylarge particles by erosion of the finer particles.attenuation,nthe amount of incident light that is scatteredand absorbed before reaching a detector,which is geometri-cally centered at 180 relative to the centerline of theincident light beam.D7937DISCUSSIONAttenuation is inversely proportional to transmittedsignal.1This terminology 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.1,2016.Published February 2016.Originallyapproved in 1984.Last previous edition approved in 2010 as D4410 10.DOI:10.1520/D4410-16.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Attenuated Turbidity5 Absorbed Light1Scattered Light(1)DISCUSSIONThe application of attenuation in this test method is asa distinct means of measuring turbidity.When measured in the FAU orAU mode,the turbidity value is a combination of scattered(attenuated)light plus absorbed light.The scattered light is affected by particle sizeand is a positive response.The absorption due to color is a negativeresponse.The sum of these two responses results in the turbidity valuein the appropriate unit.automatic power control(APC),nthe regulation of lightpower from a source such that illumination of the sampleremains constant with time and temperature.D7937avulsion,na sudden,natural change of a stream channel,sothat the water flows elsewhere than in its previous co