Hydrometry -- Acoustic Doppler profiler -- Method and application for measurement of flow in open channels from a moving boat

Hydrométrie -- Profileurs acoustiques à effet Doppler -- Méthode et application pour le mesurage de l'écoulement à surface libre sur un bateau mobile

General Information

Status

Published

ICS

17.120.20 - Flow in open channels

Technical Committee

ISO/TC 113/SC 1 - Velocity area methods

Drafting Committee

ISO/TC 113/SC 1/WG 11 - Revision of ISO/TR 24578

Current Stage

5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat

Start Date

07-Oct-2020

Completion Date

07-Oct-2020

Ref Project

RELATIONS

Revised

ISO/TR 24578:2012 - Hydrometry -- Acoustic Doppler profiler -- Method and application for measurement of flow in open channels

Effective Date

06-Feb-2016

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Standards Content (sample)

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 24578
ISO/TC 113/SC 1
Hydrometry — Acoustic Doppler
Secretariat: BIS
profiler — Method and application for
Voting begins on:
20201007 measurement of flow in open channels
from a moving boat
Voting terminates on:
20201202
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
ISO/FDIS 24578:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2020
---------------------- Page: 1 ----------------------
ISO/FDIS 24578:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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
CP 401 • Ch. de Blandonnet 8
CH1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 24578:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principles of the boat mounted ADCP method ...................................................................................................................... 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Doppler principle applied to moving objects ............................................................................................................... 4

4.3 Acoustic Doppler current profiler techniques ............................................................................................................. 5

4.3.1 General...................................................................................................................................................................................... 5

4.3.2 Pulse incoherent............................................................................................................................................................... 5

4.3.3 Pulsetopulse coherent ............................................................................................................................................. 6

4.3.4 Broadband (Spread spectrum) ............................................................................................................................ 6

4.4 Measurement of velocity profile .............................................................................................................................................. 6

4.4.1 General...................................................................................................................................................................................... 6

4.4.2 Measurement of relative velocity ...................................................................................................................... 6

4.4.3 Measurement of boat velocity .............................................................................................................................. 6

4.4.4 Near boundary data collection ............................................................................................................................ 8

4.5 Speed of sound in water ...............................................................................................................................................................10

5 Flow determination ........................................................................................................................................................................................11

5.1 General method ...................................................................................................................................................................................11

5.2 Measurement procedure .............................................................................................................................................................13

5.3 Method dealing with moving-bed condition without GNSS system ......... ..............................................15

5.3.1 General...................................................................................................................................................................................15

5.3.2 Stationary moving-bed method .......................................................................................................................15

5.3.3 Azimuth method ............................................................................................................................................................16

5.3.4 Subsection correction method ..........................................................................................................................16

5.3.5 Loop method ....................................................................................................................................................................17

5.3.6 Midsection method ...................................................................................................................................................19

6 Site selection ..........................................................................................................................................................................................................19

6.1 General ........................................................................................................................................................................................................19

6.2 Siteselection criteria .....................................................................................................................................................................20

7 ADCP Deployment procedure ..............................................................................................................................................................21

7.1 Deployment techniques................................................................................................................................................................21

7.1.1 General...................................................................................................................................................................................21

7.1.2 Manned boat mounted .............................................................................................................................................21

7.1.3 Tethered boat ...................................................................................................................................................................21

7.1.4 Deployment on a remote-control craft ......................................................................................................22

7.1.5 Data retrieval modes .................................................................................................................................................22

7.2 Operation of boat ...............................................................................................................................................................................22

7.2.1 Boat path ..............................................................................................................................................................................22

7.2.2 Boat speed ..........................................................................................................................................................................23

7.3 Field procedures .................................................................................................................................................................................23

7.3.1 Pre-field procedures ..................................................................................................................................................23

7.3.2 Field setup ..........................................................................................................................................................................23

7.3.3 Reviewing ADCP data during measurement .........................................................................................26

7.3.4 Post measurement requirements ...................................................................................................................26

7.4 Ancillary equipment ........................................................................................................................................................................27

7.5 Other consideration .........................................................................................................................................................................27

7.5.1 Edge distances ................................................................................................................................................................27

7.5.2 Depth measurements at sites with high sediment concentrations ...................................27

7.5.3 GNSS compass .................................................................................................................................................................28

7.6 Maintenance and ADCP checks ..............................................................................................................................................28

7.6.1 General...................................................................................................................................................................................28

7.6.2 Builtin diagnostic check ........................................................................................................................................28

7.6.3 Periodic major service in the manufacturer .........................................................................................28

7.6.4 Periodic ADCP performance check ...............................................................................................................28

7.6.5 Physical maintenance ...............................................................................................................................................28

7.6.6 Beamalignment test .................................................................................................................................................29

7.7 Training ......................................................................................................................................................................................................29

8 Uncertainty ..............................................................................................................................................................................................................29

8.1 General ........................................................................................................................................................................................................29

8.2 Definition of uncertainty .............................................................................................................................................................29

8.3 Uncertainties in ADCP measurements — General considerations .........................................................30

8.4 Sources of uncertainty ...................................................................................................................................................................30

8.5 Minimizing uncertainties ............................................................................................................................................................31

Annex A (informative) Velocity distribution theory and the extrapolation of velocity profiles .........32

Annex B (informative) Determination of edge discharges .........................................................................................................34

Annex C (informative) Example of an equipment check list .....................................................................................................36

Annex D (informative) Example of ADCP gauging field sheets ...............................................................................................38

Annex E (informative) Beam alignment test ..............................................................................................................................................42

Annex F (informative) Uncertainty evaluation methods ..............................................................................................................44

Bibliography .............................................................................................................................................................................................................................45

iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 24578:2020(E)
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 nongovernmental, 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 of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 113 Hydrometry, Subcommittee SC 1

Velocity area methods.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/FDIS 24578:2020(E)
Introduction

The term acoustic Doppler current profilers (ADCP) has been adopted as a generic term for a technology

that is manufactured by various companies worldwide. They are also called acoustic Doppler velocity

profilers (ADVPs) or acoustic Doppler profilers (ADPs).

To use this document effectively, it is essential that users are familiar with the terminology and

functions of their own ADCP equipment. Users should also be familiar with additional requirements.

vi © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 24578:2020(E)
Hydrometry — Acoustic Doppler profiler — Method and
application for measurement of flow in open channels
from a moving boat
1 Scope

This document gives guidelines for the use of boat-mounted acoustic Doppler current profilers (ADCPs)

for determining flow in open channels. It describes a number of methods of deploying ADCPs to

determine flow. Although, in some cases, these measurements are intended to determine the stage-

discharge relationship of a gauging station, this document deals only with single determination of

discharge.

ADCPs can be used to measure a variety of parameters, such as current or stream flow, water velocity

fields, and channel bathymetry. As a potential application, an idea of bedload discharge can be

obtained applying the bottom track velocity, while suspended sediment flow can be obtained applying

the acoustic backscatter and the sonar equation. This document is generic in form and contains no

operational details specific to particular ADCP makes and models.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 772 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
transducer depth
ADCP depth
draft
depth of the ADCP transducers below the water surface during deployment (3.6)
Note 1 to entry: The ADCP depth should be measured manually.
3.2
bin
depth cell

truncated coneshaped volume of water at a known distance and orientation from the transducers

Note 1 to entry: The ADCP determines an estimated velocity for each cell using a centre-weighted averaging

scheme, which takes account of the water not only in the bin itself but also in the two adjacent bins.

© ISO 2020 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/FDIS 24578:2020(E)
3.3
blanking distance
blank

distance travelled by the signal when the vibration of the transducer during transmission prevents the

transducer from receiving echoes or return signals

Note 1 to entry: This is the distance immediately below the ACDP transducers in which no measurement is taken.

Note 2 to entry: The distance should be the minimum possible. However, care should be taken not to make the

distance too short in order to avoid signal contamination by ringing or bias due to flow disturbance.

Note 3 to entry: If software allows it, blanking distance may be set to zero to reduce the blanking distance.

During postprocessing, user has option to choose to keep or reject this value near ADCP. This is useful when

depth is very low.
3.4
bottom tracking

acoustic method used to measure boat speed and direction by computing the Doppler shift of sound

reflected from the stream bed relative to the ADCP

Note 1 to entry: With no moving bed, the discharge can be computed with bottom velocity and water velocity data

because this is done in ADCP coordinates not earth coordinates. With moving bed, the use of a Global Navigation

Satellite System (GNSS) or loop-corrected data using a calibrated compass is required.

3.5
real-time mode

mode in which the ADCP relays information to the operating computer as it gathers it

Note 1 to entry: The ADCP and computer are connected (physically or wireless) throughout the deployment (3.6)

in this mode.
3.6
deployment

ADCP initialized and activated to collect data while the ADCP is propelled across the section to

record data

Note 1 to entry: A deployment typically includes several pairs of transects (3.11) or traverses across a river or

estuary.
3.7
deployment method
technique used to propel the ADCP across a watercourse

Note 1 to entry: One of three different deployment methods is used: a manned boat; a tethered boat; or a remote-

controlled boat.
3.8
ensemble
profile
single measurement of the water column

Note 1 to entry: A column of bins (3.2) is equivalent to a vertical in conventional current meter gauging.

3.9
ping

entirety of the sound generated by an ADCP transducer for a single measurement cycle

Note 1 to entry: Sound pulses transmitted by the ADCP for a single measurement.
2 © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/FDIS 24578:2020(E)
3.10
self-contained mode
autonomous mode

data retrieval mode in which the ADCP stores the information it gathers within its own memory and

then downloaded to a computer after deployment (3.6)

Note 1 to entry: This method is generally not used by majority of ADCP practitioners nor recommended by the

majority of hydrometric practitioners.
3.11
transect
pass
one sweep across the watercourse during an ADCP deployment (3.6)

Note 1 to entry: In the self-contained mode (3.10), a deployment can consist of any number of transects.

4 Principles of the boat mounted ADCP method
4.1 General

The ADCP is a device for measuring current velocity and direction, throughout the water column, in

an efficient and non-intrusive manner. It can produce an instantaneous velocity profile through the

water column while disturbing only the top few decimetres. ADCPs nominally work using the Doppler

principle (see 4.2). An ADCP is usually a cylinder with a transducer head on the end (see Figure 1). The

transducer head is typically a ring of three or more acoustic transducers with their faces angled to

the horizontal and at specified angles to each other. Some ADCPs use phased array transducers, which

contain many elements that can form multiple beams at various angles, depending on transducer

design. A single phased array transducer can form the three or more beams needed for an ADCP.

Key
1 forward
2 port or left
3 starboard or right
4 aft or backward

NOTE ADCP can work in any position or orientation; this figure is an indicative illustration.

Figure 1 — Example sketch illustrating typical ADCP with four transducers
© ISO 2020 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO/FDIS 24578:2020(E)

The ADCP, which was originally developed for oceanographic work, has since been developed for use in

estuaries and rivers. An ADCP can be mounted on a boat, flotation collar, or raft, and propelled across

a river (see Figure 2). The ADCP collects velocity data, direction of flow, depth data, and boat speed,

direction, and position. With such information, discharge values are independent of the path; in other

words, the route taken does not need to be straight or perpendicular to the bank.

Key
1 start
2 path of boat
3 path of boat on river bottom
4 flow velocity vectors
5 finish
Figure 2 — Sketch illustrating moving — Boat ADCP deployment principles
4.2 Doppler principle applied to moving objects

The ADCP uses ultrasound to measure water velocity using a principle of physics discovered by

Christian Doppler. The reflection of sound waves from a moving particle causes a change in frequency

to the reflected sound wave. The difference in frequency between the transmitted and reflected sound

wave is known as the Doppler shift (see Figure 3).

It should be noted that only components of velocity parallel to the direction of the sound wave produce

a Doppler shift. Thus, particles moving at right angles to the direction of the sound waves (i.e. with no

velocity components in the direction of the sound wave) will not produce a Doppler shift.

4 © ISO 2020 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/FDIS 24578:2020(E)

Figure 3 — Reflection of sound — Waves by a moving particle results in an apparent change in

the frequency of those sound waves

Doppler’s principle relates the change in frequency to the relative velocities of the source (reflector)

and the observer. In the case of most ADCPs, the transmitted sound is reflected off particulates or air

bubbles in the water column and reflected back to the transducer. It is assumed that the particulates

move at the same velocity as the water and, from this, the frequency shift can be translated to a velocity

magnitude and direction. The particulates in the river are generally suspended sediments (SS). Too

low SS concentration results in no data because of no back signal, while too high SS disrupt the signal,

and also results in no data. Therefore, ADCP frequency shall be chosen according to these criteria. The

more suspended sediment that are in water, the lower the ADCP operating frequency should be. In

addition to that, it should also be noted that excessive air bubbles can cause distortion in, or loss of, the

returned signal. Furthermore, air bubbles naturally rise and therefore are likely not to be travelling in a

representative magnitude and direction.
4.3 Acoustic Doppler current profiler techniques
4.3.1 General

There are three general types of ping configuration and processing algorithms used in ADCPs:

— pulse incoherent (including narrowband) — Doppler shift long pulse,
— pulsetopulse coherent — Doppler shift short pulse, and
— broad band (spread spectrum) — phase shift on two short pulses.
Reference should be made to the ADCP manual to determine the type being used.
4.3.2 Pulse incoherent

An incoherent ADCP transmits a single, relatively long, pulse of sound and measures the Doppler shift,

which is used to calculate the velocity of the particles along the path of the acoustic beam. The velocity

measurements made using incoherent processing are very robust over a large velocity range, although

they have a relatively high short-term (single ping) uncertainty. To reduce the uncertainty, multiple

pulses are transmitted over a short time period; these are then averaged before reporting a velocity.

“Narrowband” is used in the industry to describe a pulse-to-pulse incoherent ADCP. In a narrowband

ADCP, only one pulse is transmitted into the water per beam per measurement (ping), and the resolution

of the Doppler shift shall take place during the duration of the received pulse. The narrowband acoustic

pulse is a simple monochromatic wave and can be processed quickly.
© ISO 2020 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO/FDIS 24578:2020(E)
4.3.3 Pulse-to-pulse coherent

Coherent ADCP systems are the most accurate of the three, although they have significant range

limitations. Coherent systems transmit one, relatively short pulse, record the return signal, and then

transmit a second short pulse when the return from the first pulse is no longer detectable. The ADCP

measures the phase difference between the two returns and uses this to calculate the Doppler shift.

Velocity measurements made using coherent processing are very precise (low short-term uncertainties),

but they have significant limitations. Coherent processing will work only in limited depth ranges and

with a significantly limited maximum velocity. If these limitations are exceeded, velocity data from a

coherent Doppler system are effectively meaningless.
4.3.4 Broadband (Spread spectrum)

Like coherent systems, broadband ADCP systems transmit two pulses and look at the phase change of the

return from successive pulses. However, with broadband systems, both acoustic pulses are within the

profiling range at the same time. The broadband acoustic pulse is complex; it has a code superimposed

on the waveform. The code is imposed on the wave form by reversing the phase and creating a

...

DRAFT INTERNATIONAL STANDARD
ISO/DIS 24578
ISO/TC 113/SC 1 Secretariat: BIS
Voting begins on: Voting terminates on:
2019-10-10 2020-01-02
Hydrometry — Acoustic Doppler profiler — Method and
application for measurement of flow in open channels

Hydrométrie — Profils Doppler acoustiques — Méthode et application pour le mesurage du débit en

conduites ouvertes
ICS: 17.120.20
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 24578:2019(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2019
---------------------- Page: 1 ----------------------
ISO/DIS 24578:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DIS 24578:2019(E)
Contents Page

4 Principles of the boat mounted ADCP method ...................................................................................................................... 3

4.2 Doppler principle applied to moving objects ............................................................................................................... 5

4.3 Acoustic Doppler Current Profiler techniques ............................................................................................................ 6

4.3.1 Introduction ......................................................................................................................................................................... 6

4.3.2 Pulse incoherent............................................................................................................................................................... 6

4.3.3 Pulse-to-pulse coherent ............................................................................................................................................. 7

4.3.4 Broadband (Spread spectrum) ............................................................................................................................ 7

4.4 Measurement of velocity profile .............................................................................................................................................. 7

4.4.1 General...................................................................................................................................................................................... 7

4.4.2 Measurement of relative velocity ...................................................................................................................... 7

4.4.3 Measurement of boat velocity .............................................................................................................................. 7

4.4.4 Near boundary data collection ............................................................................................................................ 9

4.5 Speed of sound in water ...............................................................................................................................................................11

5.2 Method dealing with moving-bed condition without GNSS system ......... ..............................................14

5.2.1 Introduction ......................................................................................................................................................................14

5.2.2 Stational method ...........................................................................................................................................................14

5.2.3 Section-by-section method ..................................................................................................................................15

5.2.4 Loop method ....................................................................................................................................................................15

5.2.5 Subsection correction method ..........................................................................................................................17

5.2.6 Azimuth method ............................................................................................................................................................18

5.3 Measurement procedure .............................................................................................................................................................18

6.2 Site-selection criteria .....................................................................................................................................................................21

7 ADCP Deployment procedure ..............................................................................................................................................................21

7.1 Deployment techniques................................................................................................................................................................21

7.1.1 Manned Boat mounted ............................................................................................................................................21

7.1.2 Tethered boat ...................................................................................................................................................................22

7.1.3 Deployment on a remote-control craft ......................................................................................................22

7.1.4 Boat path ..............................................................................................................................................................................22

7.1.5 Boat speed ..........................................................................................................................................................................23

7.1.6 Data retrieval modes .................................................................................................................................................23

7.2 Field procedures .................................................................................................................................................................................23

7.2.1 Pre-field procedures ..................................................................................................................................................23

7.2.2 Field setup ..........................................................................................................................................................................24

7.2.3 Reviewing ADCP data during measurement .........................................................................................25

7.2.4 Configuration parameters .....................................................................................................................................26

7.2.5 Post measurement requirements ...................................................................................................................27

7.3 Ancillary equipment ........................................................................................................................................................................27

7.4 Others ...........................................................................................................................................................................................................28

7.4.1 Edge distances ................................................................................................................................................................28

7.4.2 Depth measurements at sites with high sediment concentrations ...................................28

7.4.3 GNSS compass .................................................................................................................................................................28

7.5 Maintenance and ADCPchecks ...............................................................................................................................................28

7.5.1 General...................................................................................................................................................................................28

7.5.2 Built-in diagnostic check ........................................................................................................................................28

7.5.3 Periodic major service .............................................................................................................................................28

7.5.4 Periodic ADCP check..................................................................................................................................................28

7.5.5 Physical maintenance ...............................................................................................................................................29

7.5.6 Beam-alignment test .................................................................................................................................................29

7.6 Training ......................................................................................................................................................................................................29

8.2 Definition of uncertainty .............................................................................................................................................................30

8.3 Uncertainties in ADCP measurements – General considerations ............................................................31

8.4 Sources of uncertainty ...................................................................................................................................................................31

8.5 Minimizing uncertainties ............................................................................................................................................................32

Annex A (informative) Velocity distribution theory and the extrapolation of velocity profiles .........33

Annex B (informative) Determination of discharge between banks and the area of

measured discharge .......................................................................................................................................................................................36

Annex C (informative) Example of an equipment check list .....................................................................................................39

Annex D (informative) Example of ADCP gauging field sheets ...............................................................................................41

Annex E (informative) Beam alignment test ..............................................................................................................................................44

Annex F (informative) Uncertainty evaluation methods ..............................................................................................................46

iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/DIS 24578:2019(E)
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.

In exceptional circumstances, when a technical committee has collected data of a different kind from

that which is normally published as an International Standard (“state of the art”, for example), it may

decide by a simple majority vote of its participating members to publish a Technical Report. A Technical

Report is entirely informative in nature and does not have to be reviewed until the data it provides are

considered to be no longer valid or useful.

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/DIS 24578 was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 1,

Velocity area methods.
© ISO 2019 – All rights reserved v
---------------------- Page: 5 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 24578:2019(E)
Hydrometry — Acoustic Doppler profiler — Method and
application for measurement of flow in open channels
1 Scope

This Standard deals with the use of boat-mounted acoustic Doppler current profilers (ADCPs) for

determining flow in open channels. It describes a number of methods of deploying ADCPs to determine

flow. Although, in some cases, these measurements are intended to determine the stage-discharge

relationship of a gauging station, this Standard deals only with single determination of discharge.

The term ADCP has been adopted as a generic term for a technology that is manufactured by various

companies worldwide. They are also called acoustic Doppler velocity profilers (ADVPs) or acoustic

Doppler profilers (ADPs). ADCPs can be used to measure a variety of parameters, such as current

or stream flow, water velocity fields, and channel bathymetry. As a potential application, an idea of

bedload discharge can be obtained applying the bottom track velocity, while suspended sediment flow

can be obtained applying the acoustic backscatter and the sonar equation. This Standard is generic in

form and contains no operational details specific to particular ADCP makes and models. Accordingly, to

use this document effectively, it is essential that users are familiar with the terminology and functions

of their own ADCP equipment. Users should also be familiar with additional requirements particular to

their own country or agency.

Most of time the discharge value measured with an ADCP consist in averaging two or more pairs of

transects depending on the river width and the expected uncertainty. The result of an ADCP gauging

consists of a discharge value with the associated uncertainty.
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 748, Hydrometry — Measurement of liquid flow in open channels using current-meters or floats

3 Terms and definitions

For the purpose of this document, the terms and definitions given in ISO 772 and the following apply:

3.1
ADCP depth
transducer depth
draft
depth of the ADCP transducers below the water surface during deployment
Note 1 to entry: The ADCP depth should be measured manually.
3.2
bin
depth cell

truncated cone-shaped volume of water at a known distance and orientation from the transducers

Note 1 to entry: The ADCP determines an estimated velocity for each cell using a center-weighted averaging

scheme, which takes account of the water not only in the bin itself but also in the two adjacent bins.

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3.3
blank
blanking distance

distance travelled by the signal when the vibration of the transducer during transmission prevents the

transducer from receiving echoes or return signals

Note 1 to entry: This is the distance immediately below the ACDP transducers in which no measurement is taken.

Note 2 to entry: The distance should be the minimum possible. However, care must be taken not to make the

distance too short in order to avoid signal contamination by ringing or bias due to flow disturbance.

Note 3 to entry: If software allows it, blanking distance may be set to zero to reduce the blanking distance.

During post-processing, user has option to choose to keep or reject this value near ADCP. This is useful when

depth is very low.
3.4
bottom tracking

this acoustic method is used to measure boat speed and direction by computing the Doppler shift of

sound reflected from the stream bed relative to the ADCP

Note 1 to entry: With no moving bed, the discharge can be computed with bottom velocity and water velocity data

because this is done in ADCP coordinates not earth coordinates. With moving bed, the use of a Global Navigation

Satellite System (GNSS) or loop-corrected data using a calibrated compass is required.

3.5
data retrieval mode
real-time mode

mode in which the ADCP relays information to the operating computer as it gathers it

Note 1 to entry: The ADCP and computer are connected (physically or wireless) throughout the deployment in

this mode.
3.6
deployment

ADCP initialized and activated to collect data while the ADCP is propelled across the section to

record data

Note 1 to entry: A deployment typically includes several pairs of transects or traverses across a river or estuary.

Note 2 to entry: When cross section measurements are not possible, the section by section method can be used.

3.7
deployment method
technique used to propel the ADCP across a watercourse

Note 1 to entry: One of three different deployment methods is used: a manned boat; a tethered boat; or a remote-

controlled boat.
3.8
ensemble
profile
single measurement of the water column

Note 1 to entry: A column of bins is equivalent to a vertical in conventional current meter gauging.

3.9
ping

a ping is the entirety of the sound generated by an ADCP transducer for a single measurement cycle

Note 1 to entry: Sound pulses transmitted by the ADCP for a single measurement.
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3.10
profiling mode
ADCP settings for type pattern of sound pulses

Note 1 to entry: Some types of equipment allow settings to be selected by the user.

Note 2 to entry: Different modes are suitable for different flow regimes, e.g. fast or slow, deep or shallow.

3.11
self-contained mode
autonomous mode

data retrieval mode in which the ADCP stores the information it gathers within its own memory and

then downloaded to a computer after deployment.

Note 1 to entry: This method is generally not used by majority of ADCP practitioners nor recommended by the

majority of hydrometric practitioners.
3.12
transect
pass
one sweep across the watercourse during an ADCP deployment

Note 1 to entry: In the self-contained mode, a deployment can consist of any number of transects.

4 Principles of the boat mounted ADCP method
4.1 General

The ADCP is a device for measuring current velocity and direction, throughout the water column, in

an efficient and non-intrusive manner. It can produce an instantaneous velocity profile through the

water column while disturbing only the top few decimetres. ADCPs nominally work using the Doppler

principle (see 4.2). An ADCP is usually a cylinder with a transducer head on the end (see Figure 1).

The transducer head is typically a ring of three or more acoustic transducers with their faces angled

to the horizontal and at specified angles to each other. Some ADCPs use phased array transducers,

which contain many elements that can form multiple beams at various angles, depending on transducer

design. A single phased array transducer can form the three or more beams needed for an ADCP.

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Key
1 forward
2 port
3 starboard
4 aft

Note ADCP can work in any position or orientation; this figure is an indicative illustration.

Figure 1 — Example sketch illustrating typical ADCP with four transducers

The ADCP was originally developed for use in the study of ocean currents – tracking them and

producing velocity profiles – and other oceanographic work. It has since been developed for use in

estuaries and rivers. An ADCP can be mounted on a boat, flotation collar, or raft, and propelled across

a river (see Figure 2). The ADCP collects measurements of velocity and direction of flow, depth, and

speed/direction/position of boat as it goes. With such information, discharge values are independent

of the path; in other words, the route taken does not need to be straight or perpendicular to the bank.

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Key
1 start
2 path of boat
3 path of boat on river bottom
4 flow velocity vectors
5 finish
Figure 2 — Sketch illustrating moving - boat ADCP deployment principles
4.2 Doppler principle applied to moving objects

The ADCP uses ultrasound to measure water velocity using a principle of physics discovered by

Christian Doppler. The reflection of sound-waves from a moving particle causes a change in frequency

to the reflected sound wave. The difference in frequency between the transmitted and reflected sound

wave is known as the Doppler shift.

It should be noted that only components of velocity parallel to the direction of the sound wave produce

a Doppler shift. Thus, particles moving at right angles to the direction of the sound waves (i.e. with no

velocity components in the direction of the sound wave) will not produce a Doppler shift.

Figure 3 — Reflection of sound - waves by a moving particle results in an apparent change in

the frequency of those sound waves

Doppler’s principle relates the change in frequency to the relative velocities of the source (reflector)

and the observer. In the case of most ADCPs, the transmitted sound is reflected off particulates or air

bubbles in the water column and reflected back to the transducer. It is assumed that the particulates

move at the same velocity as the water and from this the frequency shift can be translated to a velocity

magnitude and direction. The particulates in river is generally suspended sediments. Too low SS

concentration results no data because of no back signal, while too high SS disrupt the signal resulting

not data. Therefore, ADCP frequency has to be chosen according with this criteria. The more suspended

sediment that are in water, the lower the ADCP operating frequency has to be. In addition to that, it

should also be noted that excessive air bubbles can cause distortion in, or loss of, the returned signal.

Furthermore, air bubbles naturally rise and therefore are likely not to be travelling in a representative

magnitude and direction. Likewise, excessive sediment in water can disrupt the signal.

4.3 Acoustic Doppler Current Profiler techniques
4.3.1 Introduction

There are three general types of ping configuration and processing algorithms used in ADCPs:

— pulse incoherent (including narrowband) – Doppler shift long pulse,
— pulse-to-pulse coherent – Doppler shift short pulse,
— broad band (spread spectrum) – phase shift on two short pulses.
Reference should be made to the ADCP manual to determine the type being used.
4.3.2 Pulse incoherent

An incoherent ADCP transmits a single, relatively long, pulse of sound and measures the Doppler shift,

which is used to calculate the velocity of the particles along the path of the acoustic beam. The velocity

measurements made using incoherent processing are very robust over a large velocity range, although

they have a relatively high short-term (single ping) uncertainty. To reduce the uncertainty, multiple

pulses are transmitted over a short time period; these are then averaged before reporting a velocity.

“Narrowband” is used in the industry to describe a pulse-to-pulse incoherent ADCP. In a narrowband

ADCP, only one pulse is transmitted into the water per beam per measurement (ping), and the resolution

of the Doppler shift must take place during the duration of the received pulse. The narrowband acoustic

pulse is a simple monochromatic wave and can be processed quickly.
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4.3.3 Pulse-to-pulse coherent

Coherent ADCP systems are the most accurate of the three, although they have significant range

limitations. Coherent systems transmit one, relatively short, pulse, record the return signal, and then

transmit a second short pulse when the return from the first pulse is no longer detectable. The ADCP

measures the phase difference between the two returns and uses this to calculate the Doppler shift.

Velocity measurements made using coherent processing are very precise (low short-term uncertainties),

but they have significant limitations. Coherent processing will work only in limited depth ranges and

with a significantly limited maximum velocity. If these limitations are exceeded, velocity data from a

coherent Doppler system are effectively meaningless.
4.3.4 Broadband (Spread spectrum)

Like coherent systems, broadband ADCP systems transmit two pulses and look at the phase change of the

return from suc
...

PROJET DE NORME INTERNATIONALE
ISO/DIS 24578
ISO/TC 113/SC 1 Secrétariat: BIS
Début de vote: Vote clos le:
2019-10-10 2020-01-02
Hydrométrie — Profileurs acoustiques à effet Doppler
— Méthode et application pour le mesurage du débit en
canaux ouverts

Hydrometry — Acoustic Doppler profiler — Method and application for measurement of flow in open

channels
ICS: 17.120.20
CE DOCUMENT EST UN PROJET DIFFUSÉ POUR
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Le présent document est distribué tel qu’il est parvenu du secrétariat du comité.

DES UTILISATEURS, LES PROJETS DE NORMES
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ISO/DIS 24578:2019(F)
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Avant-propos ................................................................................................................................................................... v

1 Domaine d'application .................................................................................................................................. 1

2 Références normatives .................................................................................................................................. 1

3 Termes et définitions ..................................................................................................................................... 2

4 Principes de la méthode d'utilisation d'ADCP depuis un bateau ................................................... 4

4.1 Généralités ......................................................................................................................................................... 4

4.2 Principe de l'effet Doppler appliqué aux objets en mouvement .................................................... 6

4.3 Techniques des profileurs acoustiques de courant à effet Doppler ............................................. 7

4.3.1 Introduction ...................................................................................................................................................... 7

4.3.2 Pulse incoherent .............................................................................................................................................. 8

4.3.3 Pulse-to-pulse coherent ................................................................................................................................ 8

4.3.4 Broadband (spread spectrum) ................................................................................................................... 8

4.4 Mesurage du profil de vitesse ..................................................................................................................... 8

4.4.1 Généralités ......................................................................................................................................................... 8

4.4.2 Mesurage de la vitesse relative .................................................................................................................. 9

4.4.3 Mesurage de la vitesse du bateau .............................................................................................................. 9

4.4.4 Collecte de données proche de la limite ............................................................................................... 11

4.5 Vitesse du son dans l'eau ........................................................................................................................... 13

5 Détermination du débit.............................................................................................................................. 14

5.1 Méthode générale ......................................................................................................................................... 14

5.2 Méthode de traitement en cas de fond mobile sans système GNSS ............................................ 16

5.2.1 Introduction ................................................................................................................................................... 16

5.2.2 Méthode stationnaire ................................................................................................................................. 17

5.2.3 Méthode des verticales successives ....................................................................................................... 17

5.2.4 Méthode de la boucle .................................................................................................................................. 18

5.2.5 Méthode de correction de sous-section ............................................................................................... 20

5.2.6 Méthode azimutale ...................................................................................................................................... 20

5.3 Mode opératoire de mesurage ................................................................................................................. 22

6 Sélection de sites .......................................................................................................................................... 24

6.1 Généralités ...................................................................................................................................................... 24

6.2 Critères de sélection des sites.................................................................................................................. 25

7 Mode opératoire de déploiement de l'ADCP ...................................................................................... 26

7.1 Techniques de déploiement ..................................................................................................................... 26

7.1.1 Utilisation depuis un bateau à équipage .............................................................................................. 26

7.1.2 Utilisation depuis un bateau attaché .................................................................................................... 26

7.1.3 Déploiement à partir d'un navire commandé à distance .............................................................. 27

7.1.4 Trajectoire du bateau ................................................................................................................................. 28

DOCUMENT PROTÉGÉ PAR COPYRIGHT

7.1.5 Vitesse du bateau ......................................................................................................................................... 28

7.1.6 Modes de récupération de données ....................................................................................................... 28

7.2 Modes opératoires de terrain .................................................................................................................. 29

7.2.1 Modes opératoires préalables aux opérations sur le terrain ...................................................... 29

publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,

7.2.2 Configuration sur le terrain ...................................................................................................................... 29

y compris la photocopie, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut

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