AS 3778.4.1-1991

1 - AS 3778.4.1-1991 MEASUREMENT WATER FLOW IN OPEN CHANNELS - MEASUREMENT USING FLOW GAUGING STRUCTURES - THIN-PLATE WEIRS
4 - PREFACE
6 - 1 SCOPE AND FIELD OF APPLICATION
6 - 2 REFERENCES
6 - 3 DEFINITIONS
6 - 4 UNITS OF MEASUREMENT
6 - 5 PRINCIPLE
6 - 6 INSTALLATION
6 - 6.1 General
6 - 6.2 Selection of site
6 - 6.3 Installation conditions
6 - 6.3.1 General
6 - 6.3.2 Weir
6 - 6.3.3 Approach channel
8 - 6.3.4 Downstream channel
8 - 7 MEASUREMENT OF HEAD
8 - 7.1 Head measuring devices
8 - 7.2 Stilling well
8 - 7.3 Head-measurement section
8 - 7.4 Head-gauge datum (gauge zero)
8 - 8 MAINTENANCE
8 - 9 RECTANGULAR THIN-PLATE WEIR
8 - 9.1 Types
10 - 9.2 Specifications for the standard weir
10 - 9.3 Specifications for installation
10 - 9.4 Specifications for head measurement
10 - 9.4.1 General
10 - 9.4.2 Determination of gauge zero
10 - 9.5 Discharge formulae – General
12 - 9.6 Formulae for the basic weir form (all values of b/B)
12 - 9.6.1 Kindsvater-Carter formula
13 - 9.6.2 SIA formula
14 - 9.7 Formulae for full-width weirs (b/B=1,0)
14 - 9.7.1 Rehbock formula (1929)
14 - 9.7.2 IMFT formula
14 - 9.8 Accuracy of discharge coefficient – Rectangular weirs
14 - 10 TRIANGULAR- NOTCH THIN-PLATE WEIR
14 - 10.1 Specifications for the standard weir
16 - 10.2 Specifications for the installation
16 - 10.3 Specifications for head measurement
16 - 10.3.1 General
16 - 10.3.2 Determination of notch angle
16 - 10.3.3 Determination of gauge zero
16 - 10.4 Discharge formulae – General
17 - 10.5 Formula for all notch angles between pi/9 and 5 pi/9 radians (20° and 100°)
17 - 10.5.1 Evaluation of Ce and kh
18 - 10.5.2 Practical limitations on alpha, h/p, p/B, h and p
18 - 10.6 Formula for specific notch angles (fully-contracted weir)
19 - 10.7 Accuracy of discharge coefficients – Triangular-notch weirs
19 - 11 ACCURACY OF DISCHARGE MEASUREMENTS
19 - 11.1 General
19 - 11.2 Sources of error
19 - 11.3 Uncertainties due to different kinds of errors
19 - 11.4 Errors in recommended coefficients
20 - 11.5 Errors in quantities measured by the user
20 - 11.6 Combination of uncertainties
20 - 12 EXAMPLES OF UNCERTAINTY CALCULATIONS
20 - 12.1 Rectangular weir
21 - 12.1.1 Uncertainties given in this calculation
21 - 12.1.2 Uncertainties estimated by the user
21 - 12.1.3 Calculated uncertainties
21 - 12.2 Triangular-notch weir
21 - 12.2.1 Uncertainties given in this calculation
21 - 12.2.2 Uncertainties estimated by the user
21 - 12.2.3 Calculated uncertainties
31 - ANNEX - GUIDE FOR THE SELECTION OF WEIRS AND FLUMES FOR THE MEASUREMENTOF THE DISCHARGE OF WATER IN OPEN CHANNELS
31 - A.1 SCOPE AND FIELD OF APPLICATION
31 - A.2 TYPES OF STANDARD WEIRS AND FLUMES
31 - A.3 CRITERIA FOR THE SELECTION OF STANDARD WEIRS OR FLUMES

Specifies methods for the measurement of water flow in open channels using rectangular and triangular-notch (V-notch) thin-plate weirs. The flow conditions considered are limited to steady, free and fully ventilated discharge. It also specifies limitations of applicability related to weir and flow geometry for the recommended equations. It is technically identical with and reproduced from ISO 1438-1:1980.

First published as AS 3778.4.1-1991.