11

44thth International Symposium on Flood Defence International Symposium on Flood Defence: : Managing Flood Risk, Reliability and Managing Flood Risk, Reliability and Vulnerability, Toronto, Ontario, Canada, May 6-8, 2008Vulnerability, Toronto, Ontario, Canada, May 6-8, 2008

J. Chen, J. Fooks and H. GoertzJ. Chen, J. Fooks and H. Goertz

Water Survey Division Water Survey Division Environment CanadaEnvironment Canada

2008.052008.05

Stage-Discharge Rating Stage-Discharge Rating with ADCP Measurementswith ADCP Measurements

22

IntroductionIntroduction

Discharge measurement techniquesDischarge measurement techniques

ADCP data analysis ADCP data analysis

Stage-discharge ratingStage-discharge rating

ConclusionsConclusions

Presentation OutlinePresentation Outline

33

Water Survey of CanadaWater Survey of Canada

44

Discharge Measurement Discharge Measurement with Traditional Techniques with Traditional Techniques

55

Limitations of Current Limitations of Current Meter MeasurementMeter Measurement

Discrete points and assumed vertical Discrete points and assumed vertical

velocity profilevelocity profile

Limited range of velocity (>6 cm/s)Limited range of velocity (>6 cm/s)

Time consumingTime consuming

Safety concernsSafety concerns

66

Discharge Measurement Discharge Measurement with Acoustic Techniques with Acoustic Techniques

77

Advantages of Acoustics Advantages of Acoustics TechniquesTechniques

Continuous velocity profiling with Continuous velocity profiling with directional capabilitydirectional capability Extended range of velocity measurementExtended range of velocity measurement Shortened field measurement timeShortened field measurement time Ability to correct data files in post-Ability to correct data files in post-processingprocessing Safety concerns decreasedSafety concerns decreased

88

Discharge Measurement Discharge Measurement with ADCPwith ADCP

From USGS report

99

Discharge Measurement Discharge Measurement with ADCP with ADCP (Cont’d)(Cont’d)

1010

Velocity Magnitude ContourVelocity Magnitude Contour

Discharge Measurement June 11, 2002

1111

Discharge Measurement Discharge Measurement with ADCP – 5 Components with ADCP – 5 Components

Top subsection

Bottom subsection

Channel subsection measurablewith an ADCP

Right banksubsection

Left banksubsection

1212

Percentage of ADCP Percentage of ADCP Measured Component QMeasured Component Q

0.08

21.1

65.66

10.31

2.85

0

10

20

30

40

50

60

70

Left Q Top Q Measured Q Bottom Q Right Q

(%)

Left Q

Top Q Measured Q

Bottom Q Right Q

1313

Correlation Among Correlation Among Component Discharges (Q-Q)Component Discharges (Q-Q)

Qtotal Qleft Qtop Qm Qbottom Qright

Qtotal -

Qleft 0.655 -

Qtop 0.936 0.851 -

Qm 0.997 0.626 0.914 -

Qbottom 0.981 0.753 0.981 0.964 -

Qright 0.503 0.310 0.473 0.471 0.538 -Pearson Correlation

1414

Correlation Analysis of Correlation Analysis of Component Discharge (H-Q)Component Discharge (H-Q)

0.622

0.479

0.9190.969 0.997 0.998

0

0.10.2

0.3

0.40.5

0.6

0.7

0.80.9

1

left Right Top Bottom Measured Total

1515

Discharge Computation Discharge Computation MethodsMethods

Standard stage-discharge ratingStandard stage-discharge rating Non-standard methods for discharge Non-standard methods for discharge

computationcomputation Index-velocity ratingIndex-velocity rating Flow-velocity distributionFlow-velocity distribution

1616

Stage vs. Measured Q RatingStage vs. Measured Q Rating

Qm = -0.5731H2 + 19.18H - 98.925

R2 = 0.996

0

9

18

27

36

5 6 7 8 9 10H (m)

Qm(m

3/s

)

1717

Stage vs. Estimated Top, Stage vs. Estimated Top, Bottom Components Q RatingBottom Components Q Rating

Qtop = 0.3512H2 - 3.8141H + 11.617

R2 = 0.9615

0

2

4

6

8

5 6 7 8 9 10H (m)

Qto

p(m

3 /s)

Qbottom = 0.1357H2 - 0.6302H - 1.1768

R2 = 0.9773

0

1

2

3

4

5

6

5 6 7 8 9 10H (m)

Qbo

ttom

(m3 /s

)

1818

Q = 0.1928H2 - 2.6567H + 9.2706

R2 = 0.9149

0

0.2

0.4

0.6

0.8

1

5 6 7 8 9 10H (m)

Qle

ft(m

3 /s)

Q = -0.2694H2 + 4.3744H - 16.973

R2 = 0.7534

0

0.2

0.4

0.6

0.8

1

5 6 7 8 9 10H (m)

Qrig

ht(m

3 /s)

Stage vs. Estimated Left, Stage vs. Estimated Left, Right Components Q RatingRight Components Q Rating

1919

Stage – Discharge RatingStage – Discharge RatingResults ComparisonResults Comparison

-30.00-20.00

-10.000.00

10.00

20.0030.00

40.0050.00

0.00 9.00 18.00 27.00 36.00 45.00Q (m3/s)

Erro

r %

Measured QUnmeasured QTop QBottom Q

2020

H&Q Rating with Single H&Q Rating with Single Transect MeasurementsTransect Measurements

Discharge measurement from each Discharge measurement from each transect is considered as an independent transect is considered as an independent measurement measurement

Significantly increase the number of Significantly increase the number of

measurements for rating curve measurements for rating curve

development development

2121

Q = -0.1647H2 + 16.482H - 96.292

R2 = 0.9994

0

9

18

27

36

45

5 6 7 8 9 10H (m)

Q(m

3 /s)

-10.00

-5.00

0.00

5.00

10.00

15.00

20.00

0.00 9.00 18.00 27.00 36.00 45.00

Q (m3/s)

Erro

r %

Verification Calibration

H&Q Rating with Single H&Q Rating with Single Transect MeasurementsTransect Measurements

2222

ADCP measurements with 5 components ADCP measurements with 5 components allow for exploration of disaggregated rating allow for exploration of disaggregated rating methodsmethods Component discharge ratingComponent discharge rating

It appears that H-Q rating quality does not vary It appears that H-Q rating quality does not vary significantly, regardless of whether discharge components significantly, regardless of whether discharge components are summed prior to rating calibration, or if individual are summed prior to rating calibration, or if individual component rating results are summedcomponent rating results are summed Component discharge percentages can provide future Component discharge percentages can provide future knowledge of error sources at particular sitesknowledge of error sources at particular sites

Conclusions Conclusions

2323

Single transect analysisSingle transect analysis Using an average of 4 transects or individual Using an average of 4 transects or individual transects does not significantly affect the H & Q transects does not significantly affect the H & Q rating accuracyrating accuracy Further study with rapidly changing stage Further study with rapidly changing stage could provide more depth to this analysiscould provide more depth to this analysis

Conclusions Conclusions (Cont’d)(Cont’d)

2424

Comments on Stage Comments on Stage Discharge RatingDischarge Rating

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

4 5 6 7 8 9 10 11 12Q (m3/s)

H (

m) Series1

Series2

Series3

Series4

2525

Comments on Stage Comments on Stage Discharge Rating Discharge Rating (Cont’d)(Cont’d)

15

16

17

18

19

20

21

22

23

10/27/2004 19:12

10/28/2004 0:00

10/28/2004 4:48

10/28/2004 9:36

10/28/2004 14:24

10/28/2004 19:12

10/29/2004 0:00

10/29/2004 4:48

Date/Time

V (

cm/s

)

0.57

0.575

0.58

0.585

0.59

0.595

0.6

0.605

0.61

H (m

etr

es)

Velocity Water Level