AS 3778.3.5-1990

1 - AS 3778.3.5-1990 MEASUREMENT OF WATER FLOW IN OPEN CHANNELS - VELOCITY-AREA METHODS - INVESTIGATION OF TOTAL ERROR
4 - PREFACE
6 - 0 Introduction
6 - 1 Scope and field of application
6 - 2 Symbols
8 - Section one : Procedure and types of errors
8 - 3 General principles of velocity- area methods and accuracy requirements
8 - 4 Composition of total error
9 - 5 Errors in mean flow velocity and depth
9 - 5.1 General
9 - 5.2 Error type I
10 - 5.3 Error type II
11 - 5.4 Error type III
12 - 6 General conclusions and recommendations
12 - 6.1 General
12 - 6.2 Error type I
12 - 6.2.1 Conclusions
13 - 6.2.2 Recommendations
13 - 6.3 Error type II
13 - 6.3.1 Conclusion
13 - 6.3.2 Recommendation
13 - 6.4 Error type III
13 - 6.4.1 Conclusions
13 - 6.4.2 Recommendations
13 - 6.5 General conclusions
15 - Section two : Recommendations for the collection of data for investigation of errors
15 - 7 Measurements and data
15 - 7.1 Individual point velocity
15 - 7.2 Mean velocity in the vertical
15 - 7.3 Finite number of verticals in the cross-section
15 - 7.4 General data
16 - 8 Data processi ng
16 - 8.1 General
16 - 8.2 Error type I
16 - 8.2.1 Finite measuring time and distribution of results
16 - 8.2.2 Correction for non-steady conditions
17 - 8.2.3 Standard deviation of velocity fluctuations
17 - 8.2.4 Autocorrelation function
18 - 8.2.5 Effect of measuring time on standard deviation-Method 1
18 - 8.2.6 Effect of measuring time on standard deviation-Method 2
18 - 8.2.7 Compilation of results
18 - 8.3 Error type II
18 - 8.3.1 Determination of mean velocity in the vertical
19 - 8.3.2 Computation rules
19 - 8.3.3 Sampling error due to velocity fluctuations
19 - 8.3.4 Sampling error due to computation rule
20 - 8.4 Error type III
20 - 8.4.1 True discharge
20 - 8.4.2 Omission of verticals
20 - 8.4.3 Mean and standard deviations of errors
21 - 8.4.4 Criteria used in choosing verticals
22 - 8.5 Total stochastic error
23 - Annex A - Characteristics of rivers from which data were collected
25 - Annex B - Example of calculation of total stochastic error
25 - B.1 Basic equation
25 - B.2 Parameters
26 - B.3 Calculation
27 - B.4 Conclusion
28 - Annex C - Effect of increasing measuring time on error
29 - Annex D - Some critera used in choosing verticals
29 - D.1 Bed profile in the cross-section
29 - D.2 Verticals equidistant
29 - D.3 Sections of equal flow
30 - Bibliography

Summarizes the results of investigations of the total error in measurements of flow by velocity-area methods. It describes the procedures used and types of errors and also gives recommendations for the collection of data for investigation of errors. It is technically identical with and reproduced from ISO/TR 7178:1983.

This Technical Report summarizes the results of investigations of the total error in measurements of flow by velocity-area methods. It describes the procedure used and types of errors (section one), and gives recommendation for the collection of data for investigations of errors (section two) with a view to supplementing the information given in ISO 1088.