ASTM_D_4410_-_10.pdf

Designation:D441010Terminology 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 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.2.Terminology2.1 Definitions:accelerated erosionerosion at a rate greater than geologic ornatural erosion.DISCUSSIONAccelerated erosion is usually associated with anthro-pogenic activities and usually reduces plant cover and increases runoff.accretiona process of sediment accumulation.aggradationthe 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 depositsediment deposited by the action of movingwater.alluviationthe process of accumulating sediment deposits atplaces where the flow is retarded.alluviuma 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.armoringthe formation of a resistant layer of relatively largeparticles by erosion of the finer particles.avulsiona sudden,natural change of a stream channel,sothat the water flows elsewhere than in its previous course.bag samplera sampler that utilizes a collapsible bag as thesample collection container.base flowstream flow that is sustained by ground water andother delayed sources.bed-loadmaterial moving on or near the stream bed byrolling,sliding,and skipping.bed-load dischargethe quantity of bed-load passing a crosssection of a stream in a unit of time.bed-load samplera device for sampling the bed-load.bed materialthe sediment mixture of which the stream bedis composed.bed-material dischargethat part of the total sediment dis-charge composed of grain sizes occurring in appreciablequantities in the bed material.bed-material loadthat part of the total load which iscomposed of particle sizes present in appreciable quantitiesin the shifting portions of the stream bed.boulder size(fluvial sediment)larger than 256 mm indiameter.braided rivera wide-and shallow-river where the flowpasses through a number of small interlaced channelsseparated by bars or shoals.channela natural or artificial waterway that periodically orcontinuously contains moving water.clay size(fluvial sediment)0.00024 to 0.004 mm in diam-eter.cobble size(fluvial sediment)64 to 256 mm in diameter.cohesive sedimentsthat material whose resistance to initialmovement or erosion depends upon the strength of the bondbetween particles.colloids(fluvial sediment)smaller than 0.00024 mm indiameter.colluvial depositsthat material accumulated along valleymargins by mass movements from the adjacent hillsides.1This terminology is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.07 on Sediments,Geomor-phology,and Open-Channel Flow.Current edition approved Feb.1,2010.Published March 2010.Originallyapproved in 1984.Last previous edition approved in 2003 as D4410 03.DOI:10.1520/D4410-10.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 composite samplea sample formed by combining two ormore individual samples or representative portions of thesamples.concentration(volume)the ratio of the volume of drysediment to the volume of the water-sediment mixture.concentration of sediment(by mass)the ratio of the massof dry sediment in a water-sediment mixture to the mass ofthe mixture.critical flowopen channel flow in which the energy,ex-pressed in terms of depth plus velocity head,is a minimumfor a given flow rate and channel.The Froude number isunity at critical flow.D5614debrisas applied to geologic debris flows,a mixture ofloose,poorly-sorted rock fragments or soil material,or both,potentially ranging from clay to boulder-size particles thatmay include fragmental organic matter and other exoticdetritus.degradationthe geologic process by which stream beds,flood plains,the bottoms of other water bodies,and otherland surfaces are lowered in elevation by the removal ofmaterial by fluids.delivery rateuse sediment delivery ratio or sediment yield,whichever is meant.deltaa sediment deposit formed where moving water isslowed by a slower moving body of water.density currentthe movement of one fluid under,through,or over another fluid of differing density.