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Routine Office Techniques

Routine Office Techniques. Streamflow Records Computation using ADVMs and Index-Velocity Methods Office of Surface Water. Overview. Real-time data. Daily data review. Check to see that: Index-velocity is in expected range Cell-end has not changed SNR is in expected range

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Routine Office Techniques

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  1. Routine Office Techniques Streamflow Records Computation using ADVMs and Index-Velocity Methods Office of Surface Water

  2. Overview

  3. Real-time data • Daily data review. Check to see that: • Index-velocity is in expected range • Cell-end has not changed • SNR is in expected range • ADVM temperature is reasonable • Cross-stream velocity has not unexpectedly changed

  4. Web display of Real-time Parameters Downstream velocity

  5. Web display of Real-time ParametersCross-stream velocity

  6. Velocity Spiking

  7. Example

  8. Web display of Real-time ParametersGage height

  9. Web display of Real-time ParametersCell End

  10. Cell End • Extreme example of a cell end that is not appropriate for the conditions in the field

  11. Web display of Real-time ParametersWater Temperature

  12. Web display of Real-time ParametersSNR

  13. Signal Amplitude • Unusually high variation in signal amplitude

  14. Internal ADVM data review • Some parameters recorded internally cannot be transmitted • Velocity in beam coordinates • Multi-cell data 6-10 • Individual beam signal amplitudes/SNRs • Internal diagnostic beam check recorded at specified interval • Pitch, roll, heading (if available) • Pressure • Velocity standard error

  15. XY Velocity – Typical Pattern Vel X Vel Y

  16. Beam Velocity – Typical Pattern Beam 1 Beam 2

  17. Beam Velocity – Atypical Pattern • Multi-cell velocity • BEAM COORDINATES • Beams are looking at different water conditions • Probably located in an eddy • Meter was moved 200 ft into the flow BEAM 1 BEAM 2

  18. Multi-cell Data – Typical Pattern • Cells 1,3,5,7,9 shown here

  19. Beam Amplitude/Instrument Noise Level • Individual signal amplitude plots can give more information then transmitted average SNR. For the example here, beam 1 probably had something blocking it for a small period of time, but the transmitted SNR would still have looked reasonable

  20. Internal Diagnostics Cell begin Cell end

  21. Pitch / Roll Pitch, roll and heading should not change more than 2 degrees over a deployment. In this example, the pitch is fine, but the roll should be watched to assure it does not drift more than shown here

  22. Pitch/Roll and Heading

  23. Vertical Beam / Pressure • For sidelooking systems, pressure helps to determine a “gate” for the vertical beam depth. • The vertical beam can easily be fouled as sediment and debris settle onto the ADVM. Pressure CANNOT be used as a vertical beam substitute

  24. Cell End / Water Depth • For uplookers, the cell end and water depth should match closely as the water depth helps determine where the cell ends when dynamic boundary is set up Argonaut-SW Argonaut-XR

  25. Velocity Standard Error Beam 1 Beam 2 Cell 1 Cell 7Cell 9

  26. Additional QA/QC • Temperature • Sensor failure can be obvious (a sudden jump to an unreasonable value) or can occur over time. • A temperature error of 5 C can result in a 1 to 1.3% bias in velocity • Currently, no easy way in NWIS to compare temperature record to environmental measurements stored in SiteVisit. Spreadsheet logs are still necessary

  27. Additional QA/QC • Signal Amplitude / Instrument Noise Level • It is not necessary to look at SNR, signal amplitude, and instrument noise level, since SNR is computed from signal amplitude and instrument noise level. • Finding an unreasonable signal amplitude value in the field will indicate major problems. However, there could be a systematic change in the signal amplitude (steadily decreasing for instance) that can easily be missed in the field if the value is reasonable and you are not looking over a long period of time. • The instrument noise level should be examined for pattern changes as well

  28. Miscellaneous Office Tasks • Archival • Index-velocity parameters within SiteVisit • Anything relating to rating development and maintenance is discussed elsewhere

  29. Example of Data Archive

  30. Example Data Archive

  31. SiteVisit • There are a couple of index-velocity specific fields and reports within SiteVisit • Under the discharge measurement section if the box next to “Index Velocity Site” is checked the following boxes will become available

  32. SiteVisit • Mean Index Velocity – the average index velocity for the measurement • Standard Section Area – The area from the stage-area rating • Standard Section Velocity – Mean channel velocity – computed automatically if area is entered (Q in this example was 3,460 cfs)

  33. Questions??

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