Importance of Testing Hydroacoustic Instruments: USGS Case Studies Kevin Oberg National Coordinator for Hydroacoustics USGS Water Mission Area

1880 – 1980: Little Change

1980 – 2000: Introduction of ADCPs st Qm Broadband Rio Grande Horizontals(ADVMs)

2000 – 2013: Rapid Change Water Mode 12

Changes in Methods

USGS Discharge Measurements, In 2013 > 70,000 discharge measurements were made. 58,000 were made using acoustic instruments Qms per workday

Motivation The performance/limitations of traditional streamgaging instruments is well documented Systematic programs for validating acoustic instruments for streamflow & other measurements have not been so well documented.

Components of USGS QA Program Acceptance Testing Tow-tank (P)Tow-tank (P) Field test (S)Field test (S) Routine QA Tow-tankTow-tank Field testField test Post- Repair Testing Tow-tank (P)Tow-tank (P) Field test (S)Field test (S)

Field Testing (Acceptance & Routine QA) Validation of Streamflow Measurements made with Acoustic Doppler Current Profilers by Kevin Oberg and David S. Mueller J. Hydr. Eng., v. 133, No. 12, p

Routine QA Example – Regattas 19 - TRDI Rio Grandes – 6 –600 kHz – 13 –1200 kHz 3 - TRDI StreamPros 1 - TRDI RiverRay 1 - Sontek/YSI RS-M9 3

Lab Testing (Acceptance & Routine QA) Every instrument recalled every three years Instrument calibration is checked & if needed recalibrated is done by USGS or manufacturer

E XAMPLES Purpose is to illustrate the kinds of things that we find / solve, and to highlight how we work with manufacturers to improve the acoustic instruments

Manufacturer Calibration Issue Date of Manufacturer Calibration

StreamPro & Radio Frequency Interference USGS hydrographers reported anamolous StreamPro data such as that shown above. Discussions with TRDI indicated that a possible source of this behavior might be RFI. StreamPro is more susceptible to RFI than other ADCPs

StreamPro Radio Frequency Interference Examination of diagnostic test results provide some indication of RFI, but are not conclusive. USGS documented spatial clusters in possible RFI. TRDI verified the problem and has developed shielding. USGS requested software to warn user of potential interference.

M9 ADCP Field Testing Results M9 SProRRay Validation measurement results showed a tendency for M9 Qms to under report discharge when 3 Mhz transducers were used. Analysis of mean cross section velocity profiles showed tendency for reductions in near-surface velocity when using 3 Mhz transducers

Flow Disturbance Investigation Velocity profile data were collected to investigate the problem – 5.3 m wide flume – 0.53 m flow depth – 0.90 m/s mean velocity M9 and StreamPro ADCPs were used with different floats

Identification of Flow Disturbance Bias Analysis of data showed that velocities as far as 16 cm from the ADCP transducers are biased. 3-D numerical simulations of the flume flow confirmed the findings. OSW Tech Memo requires use of screen distance of 16 cm from the transducer face

Testing Process – M9 ADCP FW 0.8x Initial release Low-velocity directional bias FW 1.x SmartPulse HD Enhanced low velocity Validated low velocity fix FW 1.5x Loop Correction Bottom track issues FW 2.0x Improved BT Added SMBA SmartPage feature Compass calibration

M9 ADCP Validations 18 validation measurements indicated good agreement with reference discharges Subsequent comparisons showed large directional biases. Cause: untested change in manufacturing process. Required > 1 year to identify, diagnose, & fix the problem.

Testing Process – M9 ADCP FW 0.8x Initial release Low-velocity directional bias FW 1.x SmartPulse HD Enhanced low velocity Validated low velocity fix FW 1.5x Loop Correction Bottom track issues FW 2.0x Improved BT Added SMBA SmartPage feature Compass calibration

Improvements from Field Testing

Information Dissemination Web pages Hydroacoustics Forums Technical Memos Manuals (TWRI & T&M) Journalshttp://hydroacoustics.usgs.gov/

Sharing Comparison Measurements

Summary Hydrologists and engineers benefit from testing done by USGS and others (but are often unaware of the work involved or even the problems that are found/resolved). Comprehensive field validations are expensive. However, field validations of HA instruments and associated software are essential to QA of instruments for hydrometric measurements. The interaction between USGS and instrument manufacturers and our ability to influence product development is extremely important to USGS and others.

Questions?

Extras

Rapid Technology Changes Broadband ADCP Neil Brown Meter Price AA Meter “Modern” ADCPs