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Measuring Two-Dimensional Surface Velocity Distribution using Two RiverSondes Ralph T Cheng CODAR OS and U. S. Geological Survey Jon R. Burau and James.

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Presentation on theme: "Measuring Two-Dimensional Surface Velocity Distribution using Two RiverSondes Ralph T Cheng CODAR OS and U. S. Geological Survey Jon R. Burau and James."— Presentation transcript:

1 Measuring Two-Dimensional Surface Velocity Distribution using Two RiverSondes Ralph T Cheng CODAR OS and U. S. Geological Survey Jon R. Burau and James DeRose U. S. Geological Survey Donald E. Barrick, Calvin C. Teague and Peter M. Lilleboe CODAR Ocean Sensors

2 Outline Radar Technology for Surface Velocity RiverSonde System Multi-Dimensional Channel Flows Two-RiverSonde for Two-Dimensional Surface Velocity Distribution Proof-of-the-Concept Experiments Threemile Slough Sacramento River at Georgiana Slough, CA Discussion of Results

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4 RiverSonde System UHF radar: 0.7-m radar wavelength (435 MHz) 3-yagi antenna system on bank Bragg scatter from 0.35-m wavelength water waves Doppler shift gives radial velocity, water phase velocity known from their wavelength Time delay (time-gating) gives distance MUSIC direction finding gives direction Estimate along-channel flow from radial velocity Straight channel: assume flow parallel to banks Complex geometry: calculate total vectors using 2 RiverSondes

5 Typical RiverSonde Deployment River Mean Flow Radar

6 Example of Radial Vectors

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8 Sacramento River near Walnut Grove, CA Delta Cross-Channel, Georgiana Slough

9 Concept of Two RiverSondes for Two-Dimensional Surface Velocity Distribution Radar line of sight RiverSonde A RiverSonde B O B A C River Bank OA = Radial Velocity A OB = Radial Velocity B OC = Total Velocity

10 Continuing Development of RiverSonde at Three Mile Slough San Francisco Bay-Delta (Cooperation with California District)

11 Threemile Slough, California Straight channel between Sacramento and San Joaquin Rivers in California Delta Tidally-dominated flow In operation for several years with a single RiverSonde One day proof-of-the-concept experiment (21 February 2007) with 2 RiverSondes Antenna interference? Antenna patterns measured in field

12 RiverSondes at Threemile Slough NorthSouth

13 Velocity Time-series at TMS

14 Threemile Slough High Velocity 02/21 19:30 GMT 02/22 00:30 GMT

15 Threemile Slough, just Before Slack

16 Threemile Slough, just After Slack

17 BASIC FINDINGS: Two-RiverSonde operating in close proximity does not have interference issues Total vectors are generated with same software used in SeaSonde for ocean currents 5- or 10-m grid spacing Manual masking of river banks Observed complex flow pattern during tidal reversal

18 Proof-of-the-Concept II: April 23-25, 2007 Sacramento River at Georgiana Slough, CA Tidally-influenced flow Flow patterns affect fish migration 2 RiverSondes 1.5 days with units on same bank 0.5 day with units on opposite banks Antenna patterns measured with a transponder on a boat USGS measurements Boat-mounted ADCP transects every 30 min for 12 hours Four Flow Stations in the region

19 Two-RiverSonde Experiment for 2D Velocity Mapping Proof-of-the-concept at Georgiana Slough

20 View From Levee Site Georgiana Slough Sacramento River DWRG LVEG

21 Data Coverage

22 Preliminary Results: Same Bank

23 Preliminary Results: Opposite Bank

24 Slack or reversal: Case 1

25 Slack or Reversal: Case 2

26 ADCP, USGS2-RiverSonde, CODAR Preliminary Results: April 24, :06 ADCP, USGS

27 Numerical Hydrodynamic Model B.C. specified Model results compared DCC Closed

28 Implementing a Detailed Numerical Model

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30 2-RiverSonde operation works well Both units on same bank or on opposite bank Total vectors generated with same software used with SeaSonde for ocean currents Unfortunately ADCP transects did not overlap with the complex flow patterns observed by 2-RiverSonde Mistakes in the current experiment lead to a better design of the next experiment Further experiment and Comparisons with in-situ data and numerical model underway Preliminary Conclusion

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