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| Titel |
A dynamic rating curve approach to indirect discharge measurement |
| VerfasserIn |
F. Dottori, M. L. V. Martina, E. Todini |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 13, no. 6 ; Nr. 13, no. 6 (2009-06-19), S.847-863 |
| Datensatznummer |
250011901
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| Publikation (Nr.) |
 copernicus.org/hess-13-847-2009.pdf |
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| Zusammenfassung |
The operational measurement of discharge in medium and large rivers is
mostly based on indirect approaches by converting water stages into
discharge on the basis of steady-flow rating curves. Unfortunately, under
unsteady flow conditions, this approach does not guarantee accurate
estimation of the discharge due, on the one hand, to the underlying steady
state assumptions and, on the other hand, to the required extrapolation of
the rating curve beyond the range of actual measurements used for its
derivation.
Historically, several formulae were proposed to correct the steady-state
discharge value and to approximate the unsteady-flow stage-discharge
relationship. In the majority of these methods, the correction is made on
the basis of water level measurements taken at a single cross section where
a steady state rating curve is available, while other methods explicitly
account for the water surface slope using stage measurements in two
reference sections. However, most of the formulae available in literature
are either over-simplified or based on approximations that prevent their
generalisation. Moreover they have been rarely tested on cases where their
use becomes essential, namely under unsteady-flow conditions characterised
by wide loop rating curves.
In the present work, an original approach, based on simultaneous stage
measurements at two adjacent cross sections, is introduced and compared to
the approaches described in the literature. The most relevant feature is
that the proposed procedure allows for the application of the full dynamic
flow equations without restrictive hypotheses. The comparison has been
carried out on channels with constant or spatially variable geometry under a
wide range of flood wave and river bed slope conditions. The results clearly
show the improvement in the discharge estimation and the reduction of
estimation errors obtainable using the proposed approach. |
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