Comparison of Discharge

Measurements Made Using the ADCP and Price Current Meters

David S. MuellerU.S. Geological SurveyOffice of Surface Water

Overview Purpose of Validation Instrument Check

Laboratory Tests Specialty Tests

Field Validation Cup meter – ADCP method comparison Collecting comparison measurements Results to date

Ongoing Work Summary and Conclusions

Purpose of Validation Assess accuracy

Requires knowledge of the true value What is the true discharge?

Assess repeatability Measurements Instruments

Data consistency and limitations Instruments (Acoustic, Mechanical, etc.) Users Field conditions

Laboratory Tests Advantages

Controlled conditions Traceable to standards Isolate specific conditions Repeatable experiments

Disadvantages Acoustic and magnetic interference Tow tank tests lack turbulence Backscatter material must be added Backscatter uniformity Flowing water – no traceable standard

Summary of ResultsMean %

DifferenceMfgr Instrument BT WT

TRDI BB-WM 1 0.96 -0.87

TRDI BB-WM 5 0.99 -0.70

TRDI Rio Grande -2.33 -0.78

SonTek ADP -1.50 -2.10

Specialty Tests Beam Alignment Test

Compare GPS to BT distance made good Acceptable ratio: 1.003 to 0.995

GPS vs BT discharges Compared where no moving bed Tests compass and bottom track

GPS vs BT ship tracks Lag in GPS data

Field Validation Advantages

Real conditions Turbulent flow Irregular bed

Difficulties Need variety of conditions Time consuming Repeatability / steady flow ??? What is the reference discharge?

Price meter or Rating

Difference in Methods AA meter

Measures water speed Direction assigned by user Discrete point measurements Velocity profile assumed

ADCP Measures 3-D velocity Profile measurements Velocity profile extrapolated at

top and bottom Continuous measurement

across stream Large spatial sampling area

`

Broadband Comparisons

12 gaging stations 9 states 31 ADCP measurements Reference

Primarily stable ratings Adjusted ratings 7 current-meter measurements to validate or

adjust ratings Characteristics

Width: 140 – 3,600 ft Mean Depth: 5 – 25 ft Mean Velocity: 0.7 – 3.8 ft/s Discharge: 758 – 59,800 cfs

Results 26 within 5% of reference All within 8% of reference

Morlock, S.E., 1996, Evaluation of acoustic Doppler current profiler measurements of river discharge, USGS WRIR 95-4218.

Initial Rio Grande Comparisons

Mississippi River at Chester, IL (9/18/2001)

102000

104000

106000

108000

110000

112000

114000

116000

118000

120000

9:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00

TIME (EDT)

DISC

HA

RG

E (c

fs)

RDI 600 BTRDI 600 GPSRDI 1200 BTRDI 1200 GPSCup Meas.Rating

Mueller, D.S., 2002, Field assessment of acoustic-Doppler based discharge measurements in ASCE Hydraulic Measurements and Experimental Methods 2002.

Initial Testing ResultsInstrument River Location Price AA Rating Meter Rating Meter RatingRDI 1,200 WM1 Mississippi Chester,Ill. -- 5,681 -- MB -- -6.6RDI 1,200 WM1 Mississippi Chester,Ill. -- 3,228 -- MB -- -4.9RDI 1,200 WM1 Kankakee Dunn Bridge, Ind. 22.62 22.45 1.2 2 -- --RDI 1,200 WM1 Missouri Hermann, Mo. -- 1,501 -- MB -- -3.3RDI 1,200 WM1 Missouri Hermann, Mo. -- 1,529 -- MB -- -2.9RDI 1,200 WM1 Kankakee Shelby, Ind. 29.79 28.32 -0.5 4.7 -- --RDI 1,200 WM1 Illinois Marseilles, Ill. 211.2 219.2 5.4 1.6 4.8 1RDI 1,200 WM1 Illinois Marseilles, Ill. 221.4 220 2.1 2.7 -0.3 0.3Average 2 2.7 2.2 -2.7RDI 1,200 WM5 Kankakee Dunn Bridge, Ind. 22.14 22.34 5.1 4.1 -- --RDI 1,200 WM5 Kankakee Shelby, Ind. 30.04 28.6 -0.8 4.2 -- --Average 2.2 4.2RDI 600 WM1 Mississippi Chester,Ill. 5,578 5,720 -2.8 -5.2 -3.9 -6.2RDI 600 WM1 Mississippi Chester,Ill. -- 5,692 -5.9 -- -6.8RDI 600 WM1 Mississippi Chester,Ill. 3,115 3,228 0.7 -2.8 -0.9 -4.3RDI 600 WM1 Mississippi Chester,Ill. -- 3,228 -- -3.6 -- -4.9RDI 600 WM1 Missouri Hermann, Mo. 1,586 1,430 **-15.3 -6.1 **-15.2 -6RDI 600 WM1 Missouri Hermann, Mo. 1,586 1,447 **-13.0 -4.6 **-12.9 -4.5RDI 600 WM1 Missouri Hermann, Mo. -- 1,501 -- -3.4 -- -3.3RDI 600 WM1 Missouri Hermann, Mo. -- 1,529 -- -2.8 -- -2.3Average -1 -4.3 -2.4 -4.8RDI 600 WM5 Kankakee Dunn Bridge, Ind. -- 22.11 -- 1.8 -- --RDI 600 WM5 Kankakee Shelby, Ind. -- 29.73 -- 5 -- --RDI 600 WM5 Kankakee Shelby, Ind. 30.3 29.17 -1 2.8 -- --Average -1 3.2

% DifferenceBottom Track GPS

% Difference

More Field Data – Much More

Reference Discharge Simultaneous measurements Sequential ADCP and reference

measurement Accurate gate, weir, or hydropower

ratings Stable accurate stage-discharge ratings

International Cooperation U.S. Geological Survey

Environment Canada

Swedish Meterologic and Hydrologic Institute (SMHI)

Norwegian Water Resources and Energy Directorate (NVE)

Rijkswaterstaat Oost – Netherlands

14

Rio Grande ValidationOberg, K.A., and Mueller, D.S., 2007, Validation of streamflow measurements made with acoustic Doppler current profilers, ASCE Journal of Hydraulic Engineering, Vol. 133, No. 12, December 2007, p. 1421-1432

Water Mode

Number of

Comps SitesMean

Depth (ft)

Mean Velocity

(ft/s)Discharge

(cfs)

Mean Percent

Diff.

Max. Percent

Diff.

1 28 11 4.6 – 29.5 1.2 – 4.9 706 – 177,000 0.5 5.6

5/11 11 6 2.1 – 7.9 0.3 – 1.7 67 – 1,560 0.3 7.1

12 61 16 1.6 – 9.3 0.3 – 4.9 64 – 6,990 -0.1 -15.9

All 100 22 1.6 – 29.5 0.3 – 4.9 64 – 177,000

0 50 100 150 2000

50

100

150

200

Reference Discharge in cms

-20 -10 0 10 200

0.02

0.04

0.06

Percent Difference from Reference

0 2000 4000 60000

1000

2000

3000

4000

5000

6000

Reference Discharge in cms

ADCP

Dis

char

ge in

cm

s

0 250 5000

250

500

0 10 20 30 40 500

10

20

30

40

50

Reference Discharge in cms

-10 -5 0 5 100

0.05

0.1

0.15

0.2

Percent Difference from Reference

Den

sity

-10 -5 0 5 100

0.05

0.1

Percent Difference from Reference

Plots of Reference Q vs ADCP Q

Mode 1Mode 5/11

Mode 12

t-Testp=0.41

t-Testp=0.75

t-Testp=0.85

Ongoing Comparison TRDI Rio Grande

Mode 12 vs Mode 5/11 TRDI Streampro

Shallow water system TRDI RiverRay (NEW!)

600 kHz phased array SonTek/YSI RiverSurveyor (NEW!)

M9 – 3 frequencies (1, 3, 0.5 MHz) M5 – 2 frequencies(1, 3 MHz)

0 500 1000 1500 2000 2500 3000 3500 4000-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

3030

Duration of Measurement in Seconds

Perc

ent D

iffer

ence

from

12-

Pass

Ave

rage

1 Pass2 Passes4 Passes6 Passes8 PassesNoise to Velocity Ratio > 2

Two points near 40 percent

Measurement Duration Analysis

Duration = Total time spent sampling

Summary and Conclusions Comparison of discharge measurement instruments

and methods is important to maintain data consistency

Laboratory test while valuable are limited Field comparisons are important for instrument and

methods comparisons Field have shown that ADCP and Price AA methods:

Produce similar discharges Display little to no bias

Continued field comparison are necessary New instruments Range of conditions

Questions