ISO 4363:2002

INTERNATIONAL ISO
STANDARD 4363
Third edition
2002-12-01
Measurement of liquid flow in open
channels — Methods for measurement of
characteristics of suspended sediment
Mesure de débit des liquides dans les canaux découverts — Méthodes de
mesurage des caractéristiques des sédiments en suspension

Reference number
©
ISO 2002
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ii © ISO 2002 – All rights reserved

Contents Page
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Units of measurement. 2
5 Selection of site. 3
6 Selection of samplers . 3
7 Measurement methods and frequencies . 3
7.1 Principle for measurement of cross-sectional mean sediment mass concentration . 3
7.2 Principle for measurement and calculation of cross-sectional mean particle size distribution . 4
7.3 Conventional method. 4
7.4 Simplified method. 7
7.5 Distribution and requirements of measurements. 8
7.6 Additional information. 8
7.7 Source and control of errors. 9
8 Calculation. 10
8.1 Sediment discharge and mass concentration. 10
8.2 Calculation of particle size distribution. 11
9 Estimation of random uncertainty and systematic error for measurement of suspended
sediment. 12
9.1 General. 12
9.2 Sources of error . 13
9.3 Estimation of component errors. 13
9.4 Total random uncertainty for measurement of cross-sectional mean sediment mass
concentration. 13
9.5 Total systematic error for one measurement of cross-sectional mean sediment mass
concentration. 14
Annex A (informative) Data collection for determining the error in measurement of cross-sectional
mean sediment mass concentration and estimation of errors. 15
Annex B (informative) Procedures and examples of methods for combining samples collected in a
cross-section . 22

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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 4363 was prepared by Technical Committee ISO/TC 113, Hydrometric determinations, Subcommittee SC 6,
Sediment transport.
This third edition cancels and replaces the second edition (ISO 4363:1993), which has been technically revised.
Annexes A and B of this International Standard are for information only.
iv © ISO 2002 – All rights reserved

Introduction
Sediment has been defined generally as solid particles that are moved or might be moved, by stream flow in a
channel. Sediment transportation creates numerous problems such as soil erosion, local scour, degradation and
aggradation of streams, siltation in irrigation canals and navigation channels, loss of capacity of reservoirs,
meandering of streams, damages to hydraulic machinery, etc. For solving varied sediment related issues arising
out of human endeavours for development and management of water resources, a comprehensive knowledge of
the mechanism of sediment transport and methods of determination of sediment load is highly essential.
Erosion is caused by water, wind, ice and human activities such as cultivation urbanization, mining, etc. Clods and
aggregates of soil in the catchment area are broken down into small particles which are thrown into suspension
and carried away as sediment. Not all the eroded material enters the stream channel. The total amount of eroded
material which travels from a source to a downstream measuring point is termed as sediment yield.
The purpose for making measurements on suspended sediment is to determine the variation of the cross-sectional
mean mass concentration and mean particle size distribution of suspended sediment in sediment transport
processes using appropriate methods at a suitable frequency; then to determine the characteristic values of
suspended sediment transport such as sediment load, mean particle size distribution, and sediment load of various
particle sizes in various periods by jointly using the data of water stage, discharge, and suspended sediment.

INTERNATIONAL STANDARD ISO 4363:2002(E)

Measurement of liquid flow in open channels — Methods for
measurement of characteristics of suspended sediment
1 Scope
This International Standard specifies conventional and simplified methods for the measurement of cross-sectional
mean suspended sediment mass concentration and mean particle size distribution. The conventional method is
used for routine measurements in periods of stable or slowly varied flow. The simplified method is mainly used for
sediment measurements for the purpose of observing the variation process of sediment transport and can be
performed under difficult conditions. Empirical relationships are established between the cross-sectional mean
suspended sediment mass concentrations and mean particle size distributions measured by conventional and
simplified methods.
The methods specified in this International Standard are applicable to suspended sediment measurements at
hydrological stations.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 31 (all parts), Quantities and units
ISO 748, Measurement of liquid flow in open channels — Velocity-area methods
ISO 772, Hydrometric determinations — Vocabulary and symbols
ISO 1000, SI units and recommendations for the use of their multiples and of certain other units
ISO 3716, Liquid flow measurement in open channels — Functional requirements and characteristics of suspended
sediment load samplers
ISO 4365, Liquid flow in open channels — Sediment in streams and canals — Determination of concentration,
particle size distribution and relative density
3 Terms and definitions
For the purposes of this International Standard, the terms and definitions given in ISO 772 and the following apply.
3.1
suspended sediment discharge
mass of suspended sediment passing through a specific cross-section of streams or canals per unit time
3.2
suspended sediment load
total mass of suspended sediment, generally expressed in mass or volume of dry sediment, passing through a
specific cross-section of streams or canals in a given period of time
3.3
vertical average sediment mass concentration
ratio of the suspended sediment discharge per unit width (q ) to the flow discharge per unit width (q) in a vertical
s
3.4
cross-sectional mean sediment mass concentration
ratio of the cross-sectional suspended sediment discharge (Q ) to the cross-sectional flow discharge (Q )
A,s A
3.5
method for combining samples collected in a cross-section
method for measurement of cross-sectional mean sediment mass concentration in accordance with the segmental
discharge-weighted principle
NOTE The method involves dividing a cross-section by verticals into several segments with equal water surface width, or
equal flow area or equal discharge. Samples are taken by a specific method in each vertical passing through each segment
centre. (The flow velocity at a sediment sampling point should be measured simultaneously with the taking of the sediment
sample or as soon as practicable after the collection of the sediment sample. In rivers subjected to rapidly changing stage, it is
strongly recommended that the sediment sample be taken at the same time as the measurement of flow velocity.) Then the
sediment mass concentration of the combined samples is determined as the cross-sectional mean sediment mass
concentration.
3.6
particle size analysis
entire technological operation for determining the ratio of sediment mass of each size group to the total sediment
mass of a sample as specified in ISO 4365
3.7
particle size distribution
distribution in ratios of sediment mass of each size group to the total sediment mass of a sample
NOTE It is generally expressed in ratios of mass of sediment coarser or finer than a given diameter to the total sediment
mass of the sample.
3.8
cross-sectional mean size distribution of suspended sediment
conceptual characteristic value representing the ratios of sediment mass of each size group to the total suspended
sediment mass in the cross-section
4 Units of measurement
4.1 The Inter
...