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Mean Vertical Velocity Profiles from ADCP River Discharge Measurement Datasets

Author(s): Le Coz Jerome; Pierrefeu Gilles; Jodeau Magali; Paquier Andre

Linked Author(s): André Paquier, Jérôme Le Coz

Keywords: Dcp; Velocity Profiles; Surface Velocity; River Gauging; Discharge Monitoring

Abstract: Experimental vertical velocity profiles were extracted from 18 series of aDcp discharge measurements. The campaigns were performed in the Sa6ne river at the CNR Saint-Georges gauging station in Lyon, France. Post-processing methods for aDcp data positioning, averaging and depth-integrating have been implemented and applied to the dataset to get 23 mean velocity profiles across the 100 m-wide section. Individual fitting by a logarithmic law gives a satisfactory representation ofthe profiles and depth-integrated velocities very close to the experimental ones (errors are typically less than 1% ). However velocities near the freesurface are overestimated. The 414 non-dimensional profiles can be represented accurately by a unit log profile except near the surface. Indeed the site-specific surface velocity coefficient is estimated to be 0. 91 ± 0. 04 instead of the unit log value (0. 88) or even the usual default value (0. 85). Fitting wake-law profile coefficients allows to reproduce the near surface velocities better. Such an analysis of site-specific vertical velocity profiles is especially useful for discharge estimate methods based on an incomplete investigation of the flow field (HaDcp, LS-PIV, radar wave scattering, etc.).


Year: 2007

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