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Sampling strategies to improve scaling parameter estimates in rivers
Shear velocity and von Kármán’s coefficient can be considered as scaling parameters for the characterization of velocity and turbulence distributions. However, few studies have assessed their accuracy in rivers. We apply a finite ensemble averaging procedure to obtain statistically representative profiles for evaluating the effects of sampling period duration. Results show that uncertainty in point statistics can be minimized by estimating sampling requirements from turbulent or morphologic scales, but such estimates do not consider non-turbulent (i.e. hydrologic) variation. Measuring at 25 Hz, durations of 3–4 minutes with at least three repetitions at each sampling point were required to reduce uncertainty to within ±10%. Sampling durations to achieve similar accuracy in other cases will vary with the number of sampling points in the profile, flow characteristics, and the nature of non-turbulent fluctuations. Overall, sampling recommendations from a consideration of scaling parameter uncertainty will greatly exceed recommendations from other studies.
Sampling strategies to improve scaling parameter estimates in rivers
Shear velocity and von Kármán’s coefficient can be considered as scaling parameters for the characterization of velocity and turbulence distributions. However, few studies have assessed their accuracy in rivers. We apply a finite ensemble averaging procedure to obtain statistically representative profiles for evaluating the effects of sampling period duration. Results show that uncertainty in point statistics can be minimized by estimating sampling requirements from turbulent or morphologic scales, but such estimates do not consider non-turbulent (i.e. hydrologic) variation. Measuring at 25 Hz, durations of 3–4 minutes with at least three repetitions at each sampling point were required to reduce uncertainty to within ±10%. Sampling durations to achieve similar accuracy in other cases will vary with the number of sampling points in the profile, flow characteristics, and the nature of non-turbulent fluctuations. Overall, sampling recommendations from a consideration of scaling parameter uncertainty will greatly exceed recommendations from other studies.
Sampling strategies to improve scaling parameter estimates in rivers
Macvicar, Bruce J. (author) / Sukhodolov, Alexander N. (author)
Journal of Hydraulic Research ; 57 ; 798-807
2019-11-02
10 pages
Article (Journal)
Electronic Resource
English
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Bed-Load Sampling in Sand-Bed Rivers
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Bed-Load Sampling in Sand-Bed Rivers
| Online Contents | 1994
Bed-Load Sampling in Sand-Bed Rivers
| Online Contents | 1997