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Mike Cook, PhD

Improved Water Resource Management Using an Acoustic Pulsed Doppler Sensor in a Shallow Open Channel. Mike Cook, PhD. Irrigation Australia July - 2012. Background. Less than 1% of freshwater worldwide is accessible to humans - Climate change, drought - Water scarcity

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Mike Cook, PhD

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  1. Improved Water Resource Management Using an Acoustic Pulsed Doppler Sensor in a Shallow Open Channel Mike Cook, PhD Irrigation AustraliaJuly - 2012

  2. Background Less than 1% of freshwater worldwide is accessible to humans - Climate change, drought - Water scarcity Agriculture represents 70% of freshwater use - Efficient use essential for ag production & water savings - Irrigation upgrades – flow matters - Flow data is often “good enough” Many governments are mandating flow monitoring - Australia Bureau of Meteorology - California Water Resources Act • Accurately measuring flow is increasingly important

  3. Development Goals Understand shallow and complex flow • Turnout or irrigation ditch Leverage SonTek expertise in pulsed Doppler technology • Better measurement for end users • Reduce high cost of instrument hardware • Including installation with minimal or no earthworks An accurate flow measurement • International requirements (Australia and California) • Better delivery information – save water Work in as shallow water as possible • Low flows add up over time

  4. Development – Data Collection • Phase 1 of SBIR from the USDA • More than 100 FlowTracker measurements in small channels • Understand complex flow conditions • In many cases more than 100 points • Isovel maps • Data used to determine • Beam angles • Proprietary flow algorithms • Disclaimer: This material is based upon work supported by the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under Agreement No. 2008-33610-19458.  Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture

  5. Development – Hardware • Phase 2 of SBIR • Relies on Pulsed-Doppler technique using timing controllers to profile water velocity in discrete layers • Newly developed High Definition feature can profile cells 2 cm apart (SmartPulseHD) • Low profile designed to operate in 8 cm of water • Beam geometry selected based on Phase I work • Profiles the vertical and horizontal distribution of velocities • Flow tested against known USGS ratings

  6. End Product – SonTek IQ • Bottom mounted / up-looking pulsed Doppler profiler (3MHz) • Measures water level • Measures water velocity • Calculates flow and total volume • Measure temperature • Adaptive velocity sampling via SmartPulseHD • Communications via RS232, SDI-12, Modbus • External power source 8-15 VDC • Developed with a grant from the USDA and significant feedback from California Polytechnic University and the University of Illinois

  7. SonTek IQ Attributes • Velocity profiling beams (4) – 3MHz • - Along axis beams (2), 25° off vertical axis • Profiles velocity along channel axis • - Skew beams (2), 60° off vertical axis & 60° off center axis • Profiles velocity in shallow water and off central axis Along Axis Beam (downstream) Skew Beam Along Axis Beam (upstream) Skew Beam Profiles the horizontal and vertical distribution of velocities

  8. SonTek IQ Attributes • Water level measured by vertical beam and pressure sensor • - Work in tandem to provide best possible water level data • - Calculates cross-sectional area of flow from area rating • High resolution temperature sensor • - Provides data for speed of sound correction • - More accurate velocity = more accurate flow data Temperature Sensor Water Level Measurement - Vertical Beam - Pressure Sensor (flow through cell)

  9. SonTek IQ Attributes • Five conductor cable (connector not wet mateable) • - Communications: RS232, SDI12, ModBus • - Power requirements: 8 - 15 VDC • Mounting brackets • - Allows for easy installation, two screws 5" (12.7 cm) apart • - Additional options for mounting - underside of the instrument (3- brass inserts) Power and Communications connector Mounting Bracket

  10. Multi-beam profiling with SmartPulseHD • Multiple profiling beams sample more or the water • Maps horizontal and vertical distribution of velocities • Adaptively samples velocity using three acoustic techniques • Pulse coherent, Pulse incoherent and Broadband • Selects acoustic technique based on: • Water depth • Water Velocity • Turbulence • Benefit for end-users • Reduces noise in the data • Provides best possible flow data

  11. SonTek IQ Data – Velocity Profile • Velocity profiles below are the same test facility in similar flow conditions – more data & less noise = better measurement Older Doppler Technology 60 Second Average IQ SmartPulseHD Technology 30 Second Average

  12. Application/Concept The SonTek IQ minimizes earthworks – in many cases decision makers are building a section for a magmeter or installing a control section made of concrete (weirs, ramp flumes, etc.).

  13. Cocopah Test Site • Site near Yuma, AZ • Cooperation of USGS (Yuma) • Upstream – culvert outlet (15m) • Downstream – ramp flume (10m) • IQ installed in trapezoidal canal • Cleaned cross-section (important) • Custom mounting frame • Comparison data • Rating curve (water level via radar) • FlowTracker measurements • Complex site due to backwater effect

  14. Cocopah Test Site – Instrument Configuration • USGS uses water level as a surrogate for flow (radar) with periodic gagings (15/3) • 5 minute Sampling interval, 3 minute Averaging interval • IQ installed on custom railing, elevated from bottom (0.31 ft)

  15. Cocopah Test Data 2 1 3

  16. Cocopah Test Results *FlowTracker comparison data †USGS Gage data Average error = -2.8%

  17. Ypsilanti Test Site Information • Site near Winterhaven, AZ • Cooperation of USGS (Yuma) • Upstream – culvert outlet (10m) • Downstream – broad crested weir (20m) • IQ installed just under walkway • Traditionally a difficult site • Broad crested weir – small changes in level means large changes in flow • Cleaned cross-section (important) • Comparison data • Rating curve (water level via bubbler) • FlowTracker measurements

  18. Ypsilanti Test Site – Instrument Configuration • – USGS uses water level as a surrogate for flow with periodic gagings (15/3) • – 3 minute Sampling interval, 3 minute Averaging interval • – IQ Installed with weighted mount, slightly raised

  19. Ypsilanti Test Data 4 1 3 2

  20. Ypsilanti Test Results † USGS gage data * FlowTracker comparison made measured 42.07 cfs Average error = 1.28%

  21. IQ Data Summary and Conclusions • SonTek-IQ was installed at traditional irrigation sites • Compared to rating curves and discreet measurements • Sites were traditionally good for monitoring water level • Typically not ideal for a velocity sensors • SonTek- IQ performance • Flow rate was within 2.8% at Cocopah • Flow rate was within 1.3% at Ypsilanti • Average error for the two sites was 1.9% • Better data means better decisions and save water • Reliable data immediately after install • No indexing was required • Velocity data is crucial for irrigation monitoring

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