ISO 8368:2019

INTERNATIONAL ISO
STANDARD 8368
Third edition
2019-11
Hydrometric determinations — Flow
measurements in open channels using
structures — Guidelines for selection
of structure
Déterminations hydrométriques — Mesure de débit dans les canaux
découverts au moyen de structures — Lignes directrices pour le choix
des structures
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 Types of structure . 2
5.1 General . 2
5.2 Thin-plate weirs . 3
5.3 Broad-crested weirs . 3
5.4 Triangular-profile weirs. 3
5.4.1 General. 3
5.4.2 Streamlined triangular-profile weirs . 4
5.4.3 Flat-V weirs . 4
5.5 Trapezoidal-profile weirs . 4
5.6 Flumes . 4
5.7 End-depth method . 4
5.8 Vertical underflow gates and radial gates . 5
5.9 Compound gauging structures . 5
5.10 Fish passes . 5
6 Factors affecting choice . 5
6.1 General . 5
6.2 Intended purpose of the structure . 6
6.3 Range of flow to be measured .14
6.4 Accuracy to which the flow is to be measured .15
6.5 Consideration of afflux and potential for submergence .15
6.6 Size and nature of channel .15
6.7 Channel slope and sediment load .16
6.8 Operation, maintenance and repair .16
6.9 Passage of fish .17
6.10 Whole life cost .17
7 Recommendations .18
7.1 Thin-plate weirs .18
7.1.1 General.18
7.1.2 Rectangular weirs .18
7.1.3 V-notch weirs .18
7.2 Broad-crested weirs .18
7.2.1 General.18
7.2.2 Round-nose weirs .18
7.2.3 Rectangular horizontal weirs.18
7.2.4 V-shaped weirs .18
7.2.5 Trapezoidal-profile weirs .19
7.3 Triangular-profile weirs.19
7.3.1 General.19
7.3.2 Streamlined triangular-profile weirs .19
7.3.3 Flat-V weirs .19
7.4 Flumes .19
7.4.1 General.19
7.4.2 Rectangular flumes .19
7.4.3 Trapezoidal flumes . . .20
7.4.4 U-throated flumes .20
7.4.5 Parshall and SANIIRI flumes .20
7.4.6 End-depth method .20
7.5 Compound gauging structures .20
7.6 Vertical underflow gates and radial gates .20
7.7 Larinier fish passes .20
8 Parameters governing choice of structures .20
Bibliography .23
iv © ISO 2019 – All rights reserved

Foreword
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URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 113, Hydrometry, Subcommittee SC 2,
Flow measurement structures.
This third edition cancels and replaces the second edition (ISO 8368:1999), which has been technically
revised.
The main changes from the previous edition are:
— the list of types of structure included in the text has been reviewed and the details of any structure
that is no longer recommended for use have been removed;
— the technical d
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