Overview of ADCP Best Practices Report

1
Overview of ADCP Best Practices Report

• Measuring Discharge with Acoustic Doppler Current
  Profilers from a Moving Boat
• Techniques and Methods Report
• Chapter 22 of Book3, Section A

2
Overview

• Why a Techniques and Methods Report
• Organization of the report
• Highlight selected topics
• Changes to existing policy
• Quick-Reference guides and other forms
• Availability of printed copies

3
Why and How

• COE funded development of two guidance reports
  for ADCP use
• Discharge
• Velocity Mapping
• Revised more general COE report to USGS specific
  TM
• USGS specific policy
• StreamPro
• Updated with latest guidance

4
Source of Material

• Little new information
• Consolidated information from
• QA/QC report
• OSW Technical Memos
• ADCP Training Classes
• Hydroacoustic Updates
• Added some changes to guidance based on latest
  experience
• Published to allow additional updates without
  republishing entire report

5
Organization

• Main Body contains guidance
• Predeployment Preparation
• Field Procedures
• Office Procedures
• Appendices contain details
• Basic ADCP Operational Concepts
• Collecting Data in Moving-Bed Conditions
• Description of Water Modes
• Beam-Alignment Tests
• Forms and Quick-Reference Guides
• Measurement Review Procedures

6
Predeployment

• Understand basic limitations of ADCP
• Apply ADCP limitations to site selection and
  expected performance in the field
• Sediment
• Unmeasured areas
• Configuration
• Compass

7
Predeployment cont.

• Instrument Quality Assurance
• Beam Alignment Test
• Recommended
• 1st acquired
• After factory repair
• After firmware or hardware upgrades
• Periodically
• Detailed procedures in Appendix D
• Typically for Rio Grandes and RiverSurveyors
• Periodic Instrument Comparison

8
Predeployment cont.

• Ancillary Equipment
• GPS
• VTG and GGA
• Echo Sounder
• Deployments and Mounts
• Other Equipment
• Final Equip Preparation and Inspection
• Verify all computer connections and
  communications before going to the field!!

9
Checklist in Appendix E
10
Field Procedures

• Site Selection
• Maybe the most important thing you do in the
  field.
• Location, shape, velocity, other
• Pre-Measurement Field Procedures
• Set clock
• Diagnostic tests
• Speed of sound (temp and salinity)
• Compass calibration
• Instrument configuration
• Use wizards
• Moving-bed tests

11
Policy Change
USGS policy (U.S. Geological Survey, 2002b Oberg
and others, 2005) requires that a moving-bed test
be conducted prior to making a discharge
measurement. In USGS training classes and in
Oberg and others (2005), an exception to
conducting a moving-bed test with every
measurement was allowed if sufficient
documentation was provided in the field folder to
justify not conducting a moving-bed test. Field
experience has shown that sediment transport
characteristics can vary greatly for the same
discharge, depending on the hydrograph shape,
source of runoff, and season of the year. Thus, a
moving bed may be detected at a location and
discharge where one was not previously detected,
or a moving bed may no longer exist at a location
and discharge where one was previously detected.
Moving-bed conditions also have been observed in
low-velocity environments (less than 1 ft/s) and
are likely caused by organic material transported
by the water. Therefore, to ensure the quality of
the data collected, every moving-boat measurement
made with an ADCP must have a recorded moving-bed
test. If a site routinely has a moving bed and
GPS is always used with the ADCP, a moving-bed
test is still required but need only be 5 minutes
in length. This requirement supersedes Oberg and
others (2005) and various USGS training materials.
12
Moving-Bed Test Requirements

• Loop test preferred
• Stationary tests
• When
• If compass calibration is not good
• If bottom tracking cannot be maintained
• StreamPro
• How
• 5-minutes in duration
• With GPS
• From a tagline or bridge or anchored
• 10-minutes in duration
• No GPS from manned or RC-boat

These criteria supersede the guidance on
stationary moving-bed tests that have been
published previously in U.S. Geological Survey
(2002b) and Oberg and others (2005).
13
Field Procedures cont.

• Discharge Measurement Procedures
• No changes to existing guidance
• Step by step quick-reference guides in Appendix
  E
• Post-Measurement Field Procedures
• An 8-pass measurement due to one or more
  transects being gt5 from mean does not constitute
  a check measurement
• Check measurements are required according to
  criteria in WSP 2175

14
Office Procedures

• Preventive Maintenance
• Saves time in the long term!!!
• Data Storage
• Follow office policy
• Put data on server (usually within 72 hours)
• Measurement Review
• Data-Quality Indicators
• Commonly Observed Problems

15
Measurement Review

• Field forms complete, understandable, and
  legible.
• Electronic files backup in field and archived in
  office.
• Number of transects appropriate and in reciprocal
  pairs.
• Configuration
• Correct and appropriate
• User input agrees with field form
• Edge, top, and bottom extrapolations appropriate

16
Measurement Review cont.

• Independent temperature measurement recorded and
  checked.
• Salinity measured and recorded.
• Moving-bed test recorded and appropriate
  procedures used.
• Slow smooth boat operation.
• Edge distance measured, recorded, and consistent
  with electronic data.
• Number and location of missing or invalid
  ensembles are acceptable.

17
Measurement Review cont.

• Number and location of invalid depth cells are
  acceptable.
• Top and bottom extrapolation methods have been
  reviewed and are appropriate.
• Measurement computations, including mean
  discharge and measurement gage height, are
  correct.

18
Missing and Invalid Data
WinRiver II
RiverSurveyor
19
Ambiguity Errors
20
Signal Attenuation
21
Beam Impinging on Wall
22
Smooth Boat Operation
WinRiver II
RiverSurveyor
23
Spikes in Streambed
24
Bad GPS
25
Appendix A Basic Concepts

• Doppler Concepts
• Narrowband and Broadband
• Computing Velocity in Orthogonal Coordinates
• Measuring a Velocity Profile
• Computing Discharge

26
Appendix B- Collecting Data in Moving-Bed
Conditions

• Cause and Effect of Moving-Bed
• Methods to Indentify a Moving Bed
• More detail than in main body of report
• Stationary, no GPS
• Stationary, with GPS
• Loop
• Methods to Account for Moving-Bed Effects
• GPS
• Loop method
• Multiple moving-bed test method
• Mid-section method
• Azimuth method

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Appendix C Description of Water Modes

• SonTek/YSI RiverSurveyor
• TRDI
• Rio Grande
• 1
• 5/11
• 12
• StreamPro
• 12
• 13, C, Low-Noise

28
Appendix D Beam-Alignment Test

• Detailed instructions and criteria for conducting
  a beam alignment test
• Typically only applied to
• Rio Grande
• RiverSurveyor

29
Appendix E Forms andQuick-Reference Guides
30
Rio Grande Quick Sheet
31
RiverSurveyor Quick Sheet
32
Appendix F Measurement Review Guides
33
Availability

• PDF version available now
• http//pubs.usgs.gov/tm/3a22/
• Linked from http//hydroacoustics.usgs.gov/
• Printed version
• 3-hole punch, loose leaf
• In printing now, available in a couple of months
• Announcement memo will be accompany printed
  version.

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Questions