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

3. The widely used approach to estimating total roughness for hydraulic studies is to first estimate a base value for the bed material, and then to add components to this base value for various extraneous flow-retarding elements. These components include:
surface irregularities
variations in shape and size of the channel
obstructions
vegetation
The composited value is then multiplied by a correction factor for meandering of the channel.

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
Mean Flow
Radar

6. Example of Radial Vectors
Average over 1 hour
5 m range cells
1 m/s ~ 10 m
Gaps may be due to blockage by trees
SNR limits coverage at far bank

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 O A B
OA = Radial Velocity A
OB = Radial Velocity B
OC = Total Velocity
River Bank C
RiverSonde B

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
North
South

13. Velocity Time-series at TMS

14. Threemile Slough High Velocity
02/22
00:30 GMT
02/21
19:30 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. Proof-of-the-concept at Georgiana Slough
Two-RiverSonde Experiment for 2D Velocity Mapping

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. Preliminary Results: April 24, 2007 13:06
ADCP, USGS
2-RiverSonde, CODAR
ADCP, USGS

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

28. Implementing a Detailed Numerical Model

29. Implementing a Detailed Numerical Model

30. Preliminary Conclusion
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