AS 3778.3.4-1990

Measurement of water flow in open channels Velocity-area methods - Collection and processing of data for determination of errors in measurement

Standards Australia

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1 - AS 3778.3.4-1990 MEASUREMENT OF WATER FLOW IN OPEN CHANNELS - VELOCITY-AREA METHODS - COLLECTION AND PROCESSING OF DATA...
4 - PREFACE
6 - 1 Scope and field of application
6 - 2 References
6 - 3 General
6 - 3.1 Principle
6 - 3.2 Occurrence of error
7 - 3.3 Sources of error
7 - 3.4 Determination of the individual components of the error
7 - 3.4.1 Errors in width
7 - 3.4.2 Errors in depth
7 - 3.4.3 Errors in determination of the mean velocity
8 - 3.4.4 Symbols
8 - 3.5 Description of the uncertainty
8 - 3.6 Total uncertainty in discharge
9 - 3.7 Evaluation of the error in the individual components
9 - 4 Data on the local point velocity
9 - 5 Data on the average velocity
9 - 5.1 Location of the vertical
9 - 5.2 Distribution of measuring points
10 - 5.3 Period of measurement of local point velocities
10 - 5.4 Number of measurements
10 - 5.5 Presentation of data
10 - 6 Data on the velocity-area method
10 - 6.1 Measurement at 0,6 times the depth
10 - 6.2 Velocity-distribution method
10 - 6.3 Presentation of data
10 - 6.4 General data
10 - 7 Integration method
11 - 8 Calibration curves
11 - 9 Distance measurements
11 - 10 Depth measurements
11 - 11 Data processing
11 - 11.1 General
11 - 11.2 Error-type I
11 - 11.2.1 Finite measuring time and distribution of results
11 - 11.2.2 Correction for non-steady conditions
12 - 11.2.3 Standard deviation of velocity fluctuations
12 - 11.2.4 Autocorrelation function
12 - 11.2.5 Effect of measuring time on standard deviation (1)
12 - 11.2.6 Effect of measuring time on standard deviation (2)
13 - 11.2.7 Compilation of results
13 - 11.3 Error-type II
13 - 11.3.1 Approximation of mean velocity in the vertical
13 - 11.3.2 Determination of the standard mean velocity in the vertical
13 - 11.3.3 Computation methods
13 - 11.3.4 Sampling error due to velocity fluctuations and computation rule
14 - 11.3.5 Sampling error due to computation rule
14 - 11.4 Error-type III
14 - 11.4.1 Restricted number of verticals
14 - 11.4.2 True discharge
14 - 11.4.3 Omission of verticals
14 - 11.4.4 Mean and standard deviations of error
15 - 11.4.5 Criteria applied in choosing the verticals
15 - 12 List of symbols
18 - Annex A - Local point velocity measurements - Report form
21 - Annex B - Average velocity measurements – Report form
24 - Annex C - Velocity-area method – Report form

Abstract

Specifies a standard basis for the collection and processing of data for the determination of individual components of the total error in the measurement of water flow in open channels by velocity-area methods. It is technically identical with and reproduced from ISO 1088:1985.

Scope

This International Standard specifies a standard basis for the collection and processing of data for the determination of individual components of the total error in the measurement of liquid flow in open channels by velocity-area methods.
For determining the discharge in open channels by the velocity-area method, components of the flow need to be measured. The total uncertainty in discharge is a combination of the uncertainties in these components. This International Standard specifies a standard basis for collecting and processing the data required to compute the component uncertainties for determining the total uncertainty in discharge. This International Standard may be used when carrying out an investigation of component uncertainties from data taken from a large sample of rivers in a basin or in a country or for international investigations.