OTT ADC Acoustic Digital Current Meter Description of

OTT ADC Acoustic Digital Current Meter: Description of meter and Results of USGS testing Dan Wagner Hydrologist Arkansas Water Science Center Hydroacoustics Webinar May 24, 2010

Outline • Description of ADC • Results of USGS Testing • New USGS Firmware / enhancements

ADC History • Released in USA December 2007 • Testing by HIF, HAWG, and WSCs from 2008 -2010 • New USGS Firmware currently in Beta Testing

System Components Figure courtesy of OTT

Handheld Display Figure courtesy of OTT

Handheld Display Operation Figure courtesy of OTT

Display Screen Figure courtesy of OTT

Location of Sample Volume ADC ADV

Measuring Principle 4 in 2 in Sample volume 1 0. 4 in § Two 6 MHz acoustic transducers § Large sample volume located in front of sensor – Large sample volume reduces potential signal-to- noise (SNR) issues, reduces error with flow angles § Two sample volumes Sensor head Figure courtesy of OTT Sample volume 2 – Improves data precision – Internal cross correlation calculation verifies measurement accuracy and identifies potential boundary issues

Measuring Principle 1. Transmit – Receive - Digitize 3. 93 in Break 2. Transmit – Receive - Digitize Cross Correlation Check for similarities Calculation of time shift Dt Calculation of flow velocity Slide courtesy of OTT 1. 97 in 0. 4 in

Depth Sensor • Calibrate by zeroing to atmospheric pressure on site (raise out of water to calibrate) • Get depth for each vertical by first lowering meter to bottom, rod offset computed automatically • Hand-held display shows target depth and actual depth for velocity measurement in vertical depending on the velocity method selected by the user. • Depth sensor can be turned off with new firmware

QA/QC Figure courtesy of OTT

QA/QC checks • With new USGS firmware, a Quick QA/QC check is performed in office (similar to ADV beam check, can print results) • Pre-measurement QA/QC check is logged with measurement file and appears on printout

Qreview Software-Data Download

Measurement Review

Arkansas Test Sites N

Vmean, Test Measurements Site Vmean, ADV Vmean, ADC % error Mud Creek 0. 03 0. 014 -53. 3 Richland Creek 0. 39 0. 45 +15. 4 Brush Creek 0. 46 0. 42 -8. 7 Baron Fork 0. 49 0. 44 -10. 2 Flint Creek nr. West Siloam Springs 0. 60 0. 58 -3. 3 Flint Creek nr. Springtown 0. 80 0. 77 -3. 3

Vmean, Test Measurements Site Vmean, ADV Vmean, ADC % error Illinois River nr. Savoy 0. 84 0. 90 +7. 1 Bear Creek 0. 85 0. 84 -1. 2 Middle Fork White River Osage Creek 1. 22 1. 14 -6. 6 1. 47 1. 45 -1. 4 Yocum Creek 1. 97 1. 95 -1. 0 White River nr. Fayetteville 2. 04 2. 05 +0. 49

Percent Difference of Velocity Measured with ADC Relative to Velocity Measured with ADV 20 10 0 0 0. 5 1 1. 5 2 -10 Percent difference from Vmean, ADV -20 -30 -40 -50 -60 Vmean, ADC in ft/s 2. 5

Percent Difference of Velocity Measured with ADC Relative to Velocity Measured with ADV 50. 00 Difference, in percent 40. 00 30. 00 20. 00 10. 00 -10. 00 -20. 00 -30. 00 -40. 00 -50. 00 0. 50 Figure courtesy of Kevin Oberg, OSW 1. 00 1. 50 2. 00 Mean Stream Velocity, in feet per second 2. 50

OTT ADC Percent Difference vs. Discharge 50. 00 40. 00 30. 00 Difference, in % 20. 00 10. 00 -10. 00 -20. 00 -30. 00 -40. 00 -50. 00 100. 00 200. 00 300. 00 400. 00 500. 00 600. 00 Discharge, in cubic feet per second Figure courtesy of Kevin Oberg, OSW 700. 00 800. 00

Velocity vs. Velocity Plot OTT ADC Velocity, in feet per second 2. 50 2. 00 1. 50 1. 00 0. 50 0. 00 0. 50 1. 00 1. 50 Flow. Tracker Velocity, in feet per second Figure courtesy of Kevin Oberg, OSW 2. 00 2. 50

Depth vs. Depth Plot 2. 50 OTT ADC Depth, in feet 2. 00 1. 50 1. 00 0. 50 0. 00 0. 50 1. 00 1. 50 Flow. Tracker Depth, in feet Figure courtesy of Kevin Oberg, OSW 2. 00 2. 50

ADC Tow Tank Testing (tow speeds 0. 10 ft/s to 8 ft/s) 2010 -03 -10; 1020 and 250176 2010 -03 -11; 1028 and 1029 12% 1020 - 6 m cable 1028 - 10 m cable 1029 - 2. 5 m cable 250176 - 2. 5 m cable 10% 8% 6% Percet Error 4% 2% 0% -2% -4% -6% -8% -10% -12% 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5 3. 0 3. 5 4. 0 4. 5 5. 0 5. 5 6. 0 6. 5 7. 0 7. 5 8. 0 Tow Speed (ft/s) Figure Courtesy of Kirk Thibideaux, HIF Accuracy Limits 1020 Data 1020 Mean 250176 Data 1028 Mean 1029 Data 1029 Mean 250176 Mean

Cosine Errors (Vertical Angles) at 2 fps Figure Courtesy of Kirk Thibideaux, HIF 25. 0% 20. 0% 15. 0% Percent Error 10. 0% 5. 0% 0. 0% -5. 0% -10. 0% -15. 0% -20. 0% -25. 0% -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 Angle Turned (Deg. ) ADC 1029 (2010 -02 -16) ADC 250176 (2010 -02 -17) ADC 1020 (2010 -02 -18) ADC 1028 (2010 -02 -19) 80 90

Cosine Errors (Horizontal Angles) at 3. 2 fps 10. 0% 8. 0% 6. 0% Percent Error 4. 0% 2. 0% 0. 0% -2. 0% -4. 0% -6. 0% -8. 0% -10. 0% -60 -50 -40 -30 -20 -10 0 10 20 30 40 Angle Turned (Deg. ) 1020 (2010 -03 -01) Figure courtesy of Kirk Thibideaux, HIF 1028 (2010 -03 -05) 1029 (2010 -03 -08) 250176 (2010 -03 -08) 50 60

ADC Pros/Cons-prior to USGS firmware Pros: Cons: • • • Depth Sensor Sample volume in front of meter Rugged Construction, cabling Rechargeable battery 2 beams-improved performance in environments with low SNR, angles Live velocity reading-can help with meter placement • • Depth Sensor Sample volume in front of meter Rechargeable battery (? ) Can’t edit erroneous stations until reviewing the measurement in Qreview Lack of beam check (“bucket test”) and/or quick field QA/QC check that is logged with measurement Lack of QA/QC warnings during measurement (i. e. , for 0. 2/0. 8 velocity discrepancies, bad correlation resulting from bad boundary conditions

Software Enhancements • Enhanced quality assurance – Including pre-deployment quality check and field quality check • Ability to enter rated Q • Expanded character limits for station name and number and addition of measurement number • Computation and recording of averaged flow angles • On-screen warning messages, a. k. a. , Measurement Guidance – Provide user with options to improve measurement results • Option to turn off depth sensor • Enhanced measurement review – Detailed discharge and quality check reports – Warning and potential quality issue logs – One-second time series data

New ADC QA/QC Warnings Figure courtesy of OTT

Questions?