Quality assurance of U.S. Geological Survey stream current meters; the meter-exchange program 1988-98

Hubbard, E.F.; Thibodeaux, Kirk G.; Duong, M.N.

doi:10.3133/ofr99221

Cited by 3 publications

(5 citation statements)

References 2 publications

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“…The mapping relationship between rotation rate and current velocity can be expressed as v = bn, where b is the hydraulic pitch that means the moving distance of water per revolution, b = l / n. Linear or piecewise linear simplified relations v = a0 + b0n are often used, where b0 is the approximate value of hydraulic pitch at high speed. The calculation results of this method in the low speed range are usually not ideal due to the internal friction [6,13] . In addition, the measurement conditions such as depth and installation deflection angle also affect the results, and the relationship between the influence law and linear formula is quite complex [10] .…”

Section: Uncertainty Sourcementioning

confidence: 99%

“…At present, the most commonly used laboratory test method is the towing through still water method [1][2][3][4][5] , and the linear formula is used to approximate the relationship between the rotor rotation rate n and the flow velocity v. Although the linear function is convenient, the error in the low velocity range is larger due to the effect of internal friction. Hubbard [6] evaluate the measurement error of priceAA and PricePygmy current meter is less than ± 1% above 0.5m/s, which can reach up to ± 6% below 0.1m/s, in the USGS report . Although this error can be reduced by using piecewise linear method, but it is still difficult to establish a quantitative relationship with environmental conditions [4] .…”

Section: Introductionmentioning

confidence: 99%

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Uncertainty Evaluation Method of Rotating Element Current Meters

Liu¹,

Hu²,

Shi³

et al. 2023

Proceedings of the 19th International Flow Measurement Conference 2022 on Flow Measurement - FLOMEKO 2022

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The main expression of the calibration results of rotating element current meter is based on the approximate linear relationship between rotation rate and velocity, and the uncertainty evaluation method is not perfect. A technical scheme with hydraulic pitch as the result of calibration is studied, and the uncertainty can be devided to standard current velocity, rotation rate and hydraulic pitch. The measurement and uncertainty evaluation method of unit velocity and background velocity are studied based on the water velocity calibration platform. The calculation method of unit rotation rate for synchronous equidistant trigger speed measurement is proposed, and the uncertainty evaluation of unit rotation rate is realized through the self-developed standard rotation rate experimental platform. The uncertainty evaluation method for the laboratory calibration and onsite measurement results of current meter is proposed, based on the analysis of the calibration results of hydraulic screw pitch and the relationship between the calibration results and environmental factors. The results show that, the uncertainty of water flow velocity standard device is 0.04%v+2mm/s, the background velocity is the main uncertainty source in laboratory calibration results. After reasonable correcting the environmental impact of positive hydraulic pitch, the change of mechanical properties caused by long-term use is the main source of uncertainty.

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Section: Uncertainty Sourcementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Uncertainty Evaluation Method of Rotating Element Current Meters

Liu¹,

Hu²,

Shi³

et al. 2023

Proceedings of the 19th International Flow Measurement Conference 2022 on Flow Measurement - FLOMEKO 2022

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“…The PP meter, essentially a 2/5th version of the PAA, is typically used for discharge measurements with low velocities and shallow depths (e.g., down to 0.09 m (0.3 ft), Table 1). Fulford ( 2001) and Hubbard et al (1999) have reported that the accuracy in velocity of the PAA and PP meters vary with velocity with the lowest accuracy (6%) at low velocities (0.08 m/s) and the best accuracy (1.1% for PAA and 1.5% for PP) at higher velocities (>0.67 m/s). These devices are considered to be highly accurate, with the second highest cost (~$3,000) of the methods evaluated.…”

Section: Jawramentioning

confidence: 99%

“…Prior to the adoption of ADVs, Price current meters were used for the majority of USGS discharge measurements (Fulford 1992) and date back to 1882 when W.G. Price developed the first prototype of this vertical axis current meter that bears his name (Hubbard et al 1999;Turnipseed and Sauer 2010). Vertical axis current meters consist of a series of conical cups arranged around a vertical axis like a wheel.…”

Section: Jawramentioning

confidence: 99%

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Evaluation of Select Velocity Measurement Techniques for Estimating Discharge in Small Streams across the United States

King

Hundt

Simonson

et al. 2022

J American Water Resour Assoc

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Multiple instruments and methods exist for collecting discrete streamflow measurements in small streams with low flows, defined here as less than 5.7 m3/s (200 ft3/s). Included in the available methods are low‐cost approaches that are infrequently used, in part, because their uncertainty is not well known. In this work, we evaluated the accuracy and suitability of three low‐cost velocity measurement methods (surface float [SF], velocity head rod [VR], and rising body [RB]) and three conventional current meters (acoustic Doppler velocimeter, and mechanical Price type AA and Price Pygmy meters) relative to discharge calculated from stable artificial hydraulic controls. A total of 231 measurements were made by 20 individuals during 88 site visits to 24 sites in eight states. Accuracies were assessed for all methods and precision was evaluated for the low‐cost methods. The median percent error was below 5% for conventional methods, and below 20% for the low‐cost methods. The SF was the most accurate (median absolute percent error 14%) and precise (mean percent precision of 11%) low‐cost method. The RB and VR, respectively, had 15% and 20% median absolute percent error and 29% and 12% mean percent precision. Results suggest that low‐cost methods, when used appropriately, can be used to estimate discharge data under low flow conditions when measurements with conventional methods are not feasible and the associated accuracies meet end‐user measurement objectives.

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