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Comparison of Discharge Measurements Made Using the ADCP and Price Current Meters. David S. Mueller U.S. Geological Survey Office of Surface Water. Overview. Purpose of Validation Instrument Check Laboratory Tests Specialty Tests Field Validation Cup meter – ADCP method comparison - PowerPoint PPT Presentation
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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