ISO 11657:2014
(Main)Hydrometry — Suspended sediment in streams and canals — Determination of concentration by surrogate techniques
Hydrometry — Suspended sediment in streams and canals — Determination of concentration by surrogate techniques
ISO 11657:2014 specifies methods for determination of the concentrations and particle-size distributions of suspended sediment in streams and canals by surrogate techniques. ISO 11657:2014 covers brief description of the operating principle of each method and details of some of the instruments available.
Hydrométrie — Sédiments en suspension dans les cours d'eau et dans les canaux — Détermination de la concentration par des techniques de substitution
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DRAFT INTERNATIONAL STANDARD ISO/DIS 11657
ISO/TC 113/SC 6 Secretariat: BIS
Voting begins on Voting terminates on
2012-12-03 2013-03-03
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Sediment in streams and canals — Determination of
concentration by surrogate techniques
Sédiments dans les cours d'eau et dans les canaux — Détermination de la concentration par des techniques
de substitution
ICS 17.120.20
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© International Organization for Standardization, 2012
ISO/DIS 11657
Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as permitted
under the applicable laws of the user’s country, neither this ISO draft nor any extract from it may be
reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic,
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ii © ISO 2012 – All rights reserved
ISO/DIS 11657
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Units of measurement.2
5 Measuring principles.2
5.1 Transmission .2
5.2 Scattering .2
5.3 Transmission – Scattering .3
6 Properties of sediment.4
6.1 General .4
6.2 Properties of individual particles.4
6.3 Bulk characteristics .4
7 Methods for determination of suspended-sediment concentration by surrogate
techniques.4
7.1 General .4
7.2 Bulk Optics.5
7.3 Laser Diffraction (LD).6
7.4 Acoustic Back Scatter (ABS) .7
8 Particle size analysis.7
8.1 Expression of particle-size distribution.7
9 Calibration and validation.7
10 Summary.10
Annex A Determination of the concentration of suspended sediment .11
Annex B Determination of the concentration of suspended sediment .15
Annex C Determination of the concentration of suspended sediment by acoustic back scatter .17
Bibliography.20
ISO/DIS 11657
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11657 was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 6, Sediment
Transport.
iv © ISO 2012 – All rights reserved
ISO/DIS 11657
Introduction
Sedimentation and sediment transport in rivers, streams and reservoirs is a world-wide
environmental, engineering, and agricultural issue. Success in managing and solving sedimentation
problems requires comprehensive knowledge of sediment movement, reliable methods of
estimation of sediment load, and improvement in data quality. The amount of sediment-transport
data being collected, however, has steadily declined in recent decades largely due to difficulty and
costs associated with field methods used for data collection. High temporal resolution data are
needed to better understand and more adequately describe many sedimentation processes.
The bed load and suspended load broadly constitute total sediment load. However, the scope of this
standard is confined to the measurement of suspended sediment. Conventional methods for
measurement of suspended-sediment concentrations and particle-size distributions in streams rely
on the principle of collecting samples of water-sediment mixture at various points in time and space
using suitable sampling equipment and deployment methods, and analyzing the samples in
laboratory for estimating the concentrations and particle-size distributions. These methods of
collecting sediment data are labour intensive and expensive and can be hazardous. Moreover, the
accuracy of these methods in estimating the sediment concentration of rivers and streams over a
period of time may not be dependable due to the large spatial and temporal variability associated
with the transport of suspended sediment.
Continuous and accurate estimation of suspended-sediment concentration is essential in certain
situations such as:
a) in hydropower projects for the safety of the turbines and other machinery, and
b) water-supply projects for monitoring water quality
c) storm water run-off from urban areas
d) long-term monitoring of sediment transport in rivers and streams, in order to obtain reliable base
lines that can be used for decision making
In such situations, automatic and cost-effective techniques are essential to collect high-quality data
on suspended-sediment concentrations and particle sizes.
Recent technological advances in the fields of optics and acoustics have provided new sediment-
surrogate technologies and methods to determine fluvial suspended-sediment fluxes and
characteristics. Some of these methods can be used to measure suspended sediment concentration
at higher resolution, with greater automation and potentially lower cost than traditional methods.
These methods involve calculating the concentration of suspended sediment from detectable optical
backscatter, laser diffraction and acoustic backscatter.
DRAFT INTERNATIONAL STANDARD ISO/DIS 11657
Hydrometry — Suspended Sediment in streams and canals -
Determination of concentration by surrogate techniques
1 Scope
1.1 This International Standard specifies methods for determination of the concentrations and
particle-size distributions of suspended sediment in streams and canals by surrogate techniques.
Methods based on bulk-optical principle of water such as transmission, nephelometry and optical
backscatter are the most commonly used surrogates for determining suspended-sediment
concentrations (SSC). Instruments and techniques based on acoustic attenuation and/or acoustic
backscatter principles are also in use for measurement of suspended-sediment concentration.
Instrumentation based on the laser diffraction principle is also used for the measurement of particle
size distribution. This Standard covers brief description of the operating principle of each method
and details of some of the instruments available.
1.2 The detailed method and principle of Nephelometry, Optical Back Scatter (OBS), Laser
Diffraction technique (LD) and Acoustic Back Scatter technique (ABS) with their limitations are
described in annexure A, B and C respectively.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of the
referenced document (including any amendments) applies.
ISO 772, Hydrometry – Vocabulary and symbols.
ISO 4363, Measurement of liquid flow in open channels – Methods for measurement of
characteristics of suspended sediment.
ISO 13320-2009, Particle size analysis – laser diffraction methods
3 Terms and definitions
For the purpose of this international standard, the definitions given in ISO 772, ISO 4363 and ISO
13320 apply, together with the following:
3.1
surrogate technique
An indirect method in which a surrogate/substitute object or property is used for measurement in
place of the original object or property.
NOTE – Optical and acoustic properties of water-sediment mixture such as optical transmission, acoustic
scattering, and laser diffraction are some of the surrogates for measurement of suspended sediment
concentration.
ISO/DIS 11657
3.2
nephelometry
Any method for estimating the concentration of particles in suspension by measuring the
intensity of scattered light (turbidity), often at right angles to the incident beam.
NOTE Light scattering depends upon number, size distribution, colour, composition (as manifested in the
complex index of refraction) and shape characteristics of the particles.
4 Units of measurement
The units of measurement used in this International Standard are SI units in accordance with
the appropriate parts of ISO 80000.
5 Measuring principles
Optical and acoustical methods are used for continuous measurement of sediment
concentration. The measuring principles for the above surrogate techniques are similar and
can be classified in three categories as follows (refer Figure 1):
5.1 Transmission
The source and detector are placed opposite to each other at a distance l as shown in figure
1 A. The sediment particles in the measuring volume reduce the beam intensity resulting in a
reduced detector signal. The relationship between the detector signal (l ) and the sediment
t
[23]
concentration ( c ) is following Beer’s Law :
−k cl
l = l e (1)
t o
where
l is the transmitted light through a sample of length l in water of sediment concentration
t
...
INTERNATIONAL ISO
STANDARD 11657
First edition
2014-07-01
Hydrometry — Suspended sediment in
streams and canals — Determination
of concentration by surrogate
techniques
Hydrométrie — Sédiments en suspension dans les cours d’eau et dans
les canaux — Détermination de la concentration par des techniques
de substitution
Reference number
©
ISO 2014
© ISO 2014
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Measuring principles . 2
4.1 Transmission . 2
4.2 Scattering . 2
4.3 Transmission — Scattering . 3
4.4 Diffraction . 3
5 Properties of sediment of importance for sediment surrogate techniques .3
5.1 General . 3
5.2 Particle size . 4
5.3 Particle colour . 4
6 Methods for determination of suspended sediment concentration by
surrogate techniques . 4
6.1 General . 4
6.2 Bulk optics . 4
6.3 Laser diffraction (LD) . 5
6.4 Acoustic back scatter (ABS) . 5
7 Calibration and validation . 6
Annex A (informative) Determination of the concentration of suspended sediment by
optical techniques . 9
Annex B (informative) Determination of the concentration of suspended sediment by laser
diffraction technique .12
Annex C (informative) Determination of the concentration of suspended sediment by acoustic
back scatter .14
Bibliography .18
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information.
The committee responsible for this document is ISO/TC 113, Hydrometry, Subcommittee SC 6, Sediment
transport.
iv © ISO 2014 – All rights reserved
Introduction
Sedimentation and sediment transport in streams, rivers, reservoirs and estuaries are key parameters
in many scientific, environmental, engineering, and agricultural problems. Success in managing and
solving sedimentation problems requires comprehensive knowledge of sediment movement. This
requires reliable methods of estimation of sediment load with high-quality data. The amount of sediment
transport data being collected, however, has steadily declined in recent decades largely due to difficulty
and costs associated with field methods used for data collection. High temporal resolution data of high
quality are needed to better understand and more adequately describe many sedimentation processes.
The bed load and suspended load broadly constitute total sediment load. However, the scope of this
International Standard is confined to the measurement of suspended sediment. Conventional methods
for measurement of suspended sediment concentrations in streams rely on the principle of collecting
samples of water-sediment mixture at various points in time and space using suitable sampling
equipment and deployment methods and analysing the samples in laboratory for estimating the sediment
concentration. These methods are labour intensive, expensive and can be hazardous. Moreover, the
accuracy of these methods in estimating the sediment concentration of rivers and streams over a period
of time may not be dependable due to the large spatial and temporal variability associated with the
transport of suspended sediment.
Continuous and accurate estimation of suspended sediment concentration is essential in certain
situations such as:
a) in hydropower projects for the safety of the turbines and other machinery, reservoir silting and
flushing;
b) water-supply projects for monitoring water quality;
c) storm water run-off from urban areas;
d) silting of wetlands; and
e) long-term monitoring of sediment transport in rivers and streams, in order to obtain reliable base
lines that can be used for decision making.
In such situations, automatic and cost-effective techniques are essential to collect high-quality data on
suspended sediment concentrations and particle sizes.
Recent technological advances in the fields of optics and acoustics have provided new sediment-
surrogate technologies and methods to determine suspended sediment fluxes and characteristics.
Some of these methods can be used to measure suspended sediment concentration at higher resolution,
with greater automation and potentially lower cost than traditional methods. These methods involve
surrogate technologies that derive the suspended sediment concentration from measurements of optical
backscatter, laser diffraction and acoustic backscatter.
The measurement of suspended sediment concentration (SSC) in the water samples can be carried out
with the help of nephelometry, transmission, laser diffraction and acoustic back scatter techniques. The
working principles, applications, advantages and disadvantages, limitations and usable instruments of
the above techniques are elaborated in this International Standard. The optical backscatter technique
is readily available and relatively inexpensive. Optical backscatter sensor sensitivity depends on grain
size, colour and composition. The advantages are small size and small sample volume, linear and
high frequency response, insensitive to ambient light, large measuring range and low cost. The laser
diffraction (LD) technique is also readily available and cost effective. The acoustic backscatter is another
technique for measurement of SSC in the aquatic ecosystems. Measurements are possible for a range of
sediment sizes that is dependent on the acoustic frequency. The available maximum sampling depth will
be limited at high concentrations.
INTERNATIONAL STANDARD ISO 11657:2014(E)
Hydrometry — Suspended sediment in streams and canals
— Determination of concentration by surrogate techniques
1 Scope
This International Standard specifies methods for determination of the concentrations and particle-size
distributions of suspended sediment in streams and canals by surrogate techniques. Methods based on
bulk-optical principle of water such as transmission and nephelometry are the most commonly used
surrogates for determining suspended sediment concentrations (SSC). Instruments and techniques
based on acoustic attenuation and/or acoustic backscatter principles are also in use for measurement of
suspended sediment concentration. Instrumentation based on the laser diffraction principle is also used
for the measurement of particle size distribution. This International Standard covers brief description
of the operating principle of each method and details of some of the instruments available.
The detailed method and principle of optical and acoustical transmission, nephelometry, and optical
back scatter (OBS), laser diffraction technique (LD) and acoustic back scatter technique (ABS) with their
limitations are described in Annex A, Annex B and Annex C respectively.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 772, Hydrometry — Vocabulary and symbols
ISO 4363, Measurement of liquid flow in open channels — Methods for measurement of characteristics of
suspended sediment
ISO 13320, Particle size analysis — Laser diffraction methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 772, ISO 4363 and ISO 13320
and the following apply.
3.1
surrogate technique
indirect method in which a substitute object or property is used for measurement in place of the original
object or property
Note 1 to entry: Optical and acoustic properties of water-sediment mixture such as optical transmission, acoustic
scattering and laser diffraction are some of the surrogates for measurement of suspended sediment concentration.
3.2
nephelometry
any method for est
...
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