ASTM_D_7512_-_09_2015.pdf

Designation:D751209(Reapproved 2015)Standard Guide forMonitoring of Suspended-Sediment Concentration in OpenChannel Flow Using Optical Instrumentation1This standard is issued under the fixed designation D7512;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 guide covers the equipment and basic proceduresfor installation,operation,and calibration of optical equipmentas a surrogate for the continuous determination of suspended-sediment concentration(SSC)in open channel flow.1.2 This guide emphasizes general principles for the appli-cation of optical measurements to be used to estimatesuspended-sediment concentration(SSC)in water.Only in afew instances are step-by-step instructions given.Continuousmonitoring is a field-based operation,methods and equipmentare usually modified to suit local conditions.The modificationprocess depends upon the operator skill and judgment.1.3 This guide covers the use of the output from an opticalinstrument,such as turbidity and suspended-solids meters,torecord data that can be correlated with suspended-sedimentconcentration.It does not cover the process of collecting datafor continuous turbidity record,which would require additionalcalibration of the turbidity readings to the mean turbidity of themeasurement cross section.For the purposes of this method itis assumed that the dependent variable will be mean cross-sectional suspended-sediment concentration data.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 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:2D3977 Test Methods for Determining Sediment Concentra-tion in Water SamplesD4411 Guide for Sampling Fluvial Sediment in MotionD7315 Test Method for Determination of Turbidity Above 1Turbidity Unit(TU)in Static Mode3.Terminology3.1 Definitions:3.1.1 calibration drift,nthe error that is the result of driftin the sensor reading from the last time the sensor wascalibrated,and is determined by the difference betweencleaned-sensor readings in calibration standards and the true,temperature-compensated value of the calibration standards.3.1.2 continuous,adjrefers to a time series of unit valuesthat are close enough in time to simulate a continuous record.3.1.2.1 DiscussionGenerally,in studies of open-channelflow,15-minute intervals are used and are adequate to esti-mated continuous record.However,the time interval maybe aslittle as a minute or as great as an hour.3.1.3 fouling,nthe error that can result from a variety ofsources(such as biological growth on the sonde and coveringof the probe with sediment),and is determined by the differ-ence between sensor measurements in the environment beforeand after the sensors are cleaned.3.1.4 sonde,npart of the monitoring equipment that con-tains the measurement sensors.3.1.4.1 DiscussionA sonde may be either a single param-eter sensor or a combination of different sensors of differentparameters.4.Summary of Guide4.1 This guide covers the equipment and basic proceduresfor installation,operation,and calibration of optical equipmentas a surrogate for the continuous or near continuous determi-nation of SSC in open channel flow.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.07 on Sediments,Geomorphology,and Open-Channel Flow.Current edition approved Jan.15,2015.Published February 2015.Originallyapproved in 2009.Last previous edition approved in 2009 as D7512 09.DOI:10.1520/D7512-09R15.2For 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 4.2 This guide emphasizes general principles for one par-ticular application of optical measurements in water.Thisguide covers the use of nephelometers and backscatter typeturbidity meters to record data that can be correlated with SSC.5.Significance and Use5.1 This guide is general and intended as a planning guide.To satisfactorily monitor a specific site,an investigator mustsometimes design specific installation structures or modifythose given in this guide to meet the requirements of the site inquestion.Because of the dynamic nature of the sedimenttransport process,the extent to which characteristics such a