Index Velocity
The water velocity measured by a hydroacoustic current meter in a portion of a river can be used as a surrogate or "index" for the mean-channel velocity. Mean-channel velocities computed using index velocity methods can be used to generate records of river streamflow.
The USGS uses fixed hydroacoustic current meters in various deployment configurations (side-looking, upward and downward-looking) for many different applications. Perhaps the most common application is at streamflow-gaging stations to compute streamflow using index velocity methods. The water velocity measured by a hydroacoustic current meter in a portion of a river can be used as a surrogate or "index" for the mean-channel velocity. Mean-channel velocities computed using index velocity methods can be used to generate records of river streamflow. Upward and/or downward-looking fixed deployments have been used to measure tidal current patterns in bays, estuaries, and harbors as well as wind-driven and density currents in lakes.
Real-time Index Velocity Examples
It can be beneficial to view real-time data from operational index velocity stations. The following links provide examples of USGS streamflow-gaging stations with real-time, online data produced from index velocity instrument and methods:
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Chicago River at Columbus Dr at Chicago, Illinois (05536123)
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Columbia River at the Dalles, Oregon (14105700) - long-term acoustic velocity meter (AVM) index velocity site
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Indiana Harbor Canal at East Chicago, Indiana (04092750) - Lake Michigan tributary with rapidly varying flow and frequent flow reversals
Index Velocity Resources
Instrument Page: Descriptions of the types of hydroacoustic current meters commonly used for index velocity applications.
Guidance: Published guidance reports, technical memorandums, and recommended procedures.
Software and Firmware: Information regarding software and firmware for commonly used acoustic Doppler velocity meters and acoustic profilers (side-looking, upward and downward-looking).
Deployments: A summary of mounts and deployments for side-looking and upward-looking applications.
Tech Tips: Quick reference sheets and other tips for deploying index velocity meters and computing discharge using the index velocity method.
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Authors
Janice M. Fulford, Scott Kimball
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Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The p
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Victor A. Levesque, Kevin A. Oberg
Computation and error analysis of discharge for the Lake Michigan Diversion Project in Illinois: 1997-99 water years
Acoustic velocity meters (AVM's) and acoustic Doppler current profilers (ADCP's) were used to measure streamflow at four streamflow-gaging stations in the Chicago River system. The streamflow data were used to compute discharge and to determine the uncertainty in the computed annual mean discharge at each station for the Lake Michigan Diversion Project in Illinois. Descriptions of the instrumentat
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James J. Duncker, Thomas M. Over, Juan A. Gonzalez
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Catherine A. Ruhl, Michael R. Simpson
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It is feasible to use acoustic Doppler velocity meters (ADVM's) installed at U.S. Geological Survey (USGS) streamflow-gaging stations to compute records of river discharge. ADVM's are small acoustic current meters that use the Doppler principle to measure water velocities in a two-dimensional plane. Records of river discharge can be computed from stage and ADVM velocity data using the 'index veloc
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Scott E. Morlock, Hieu T. Nguyen, Jerry H. Ross
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D.P. Turnipseed
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Clinton Hittle, Eduardo Patino, Mark A. Zucker
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No abstract available.
Authors
R. T. Cheng, C. -H. Ling, J. W. Gartner
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R. T. Cheng, C. -H. Ling, J. W. Gartner, P.-F. Wang
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Index-velocity data collected with acoustic velocity meters, stage data, and cross-sectional area data were used to calculate discharge at three low-velocity, tidal streamflow stations in north-east Florida. Discharge at three streamflow stations was computed as the product of the channel cross-sectional area and the mean velocity as determined from an index velocity measured in the stream using a
Authors
J. V. Sloat, W. S. Gain
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Acoustic velocity meter (AVM) accuracy depends on equipment limitations, the accuracy of acoustic-path length and angle determination, and the stability of the mean velocity to acoustic-path velocity relation. Equipment limitations depend on path length and angle, transducer frequency, timing oscillator frequency, and signal-detection scheme. Typically, the velocity error from this source is about
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Antonius Laenen, R. E. Curtis
AreaComp Hydroacoustics Software
AreaComp is a software for computing stage area ratings from hydrologic measurements.