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| Titel |
Alternative method for estimating the cross-sectional interpolation errors of discharge measurements using the velocity-area method |
| VerfasserIn |
Aurélien Despax, Christian Perret, Rémy Garçon, Alexandre Hauet, Arnaud Belleville, Jerome Le Coz, Anne-Catherine Favre |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131374
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| Publikation (Nr.) |
 EGU/EGU2016-11775.pdf |
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| Zusammenfassung |
| Quantifying the quality of discharge measurements by uncertainty analysis is a challenge in
the hydrometric community. Discharge measurements are the first step to produce
hydrometric data which are used in many hydrological studies like design of hydraulic
structures or calibration of hydrological models for flood forecasting and warning. Thus
associated uncertainty has to be estimated carefully. The velocity-area method is a
common approach for estimating river discharge. It consists in integrating depths
and point velocities through the cross-section. Due to the limited number of point
measurements, the quality of the measurement depends mainly on the sampling
strategy.
Different methods of uncertainty estimation are available in the literature (ISO 748,
Q+ and IVE). The main uncertainty component, noted um, is often related to the
cross-sectional interpolation errors. However the computation of this term according to these
approaches does not evaluate both the sampling strategy and the complexity of the
cross-section.
The FLAURE method (FLow Analog UnceRtainty Estimation) includes a new methodology
to estimate this term. It is based on the study of high-resolution stream-gaugings (i.e.
reference stream-gaugings made with a high number of verticals). The high-resolution
measurements are first subsampled by reducing the number of verticals to generate a sample
of realistic stream-gaugings. A statistical analysis is performed to estimate the um component
and then a sampling quality index is defined. For each reference stream-gauging, it leads to a
curve of um component as a function of the sampling quality index. This set of curves is
finally used to compute the um component of any routine stream-gauging. Curves are
then selected according to the similitude between the routine stream-gauging and
reference stream-gaugings. The similitude between the routine stream-gauging
and reference stream-gaugings is evaluated thanks to the Nash criteria computed
on lateral velocity distribution and bathymetric profile. The main advantage of
this new methodology is to take into account both the sampling strategy and the
complexity of the cross-section. Its application is adequate for various cross-sectional
configurations including complex cross-sections and smooth man-made channels. |
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