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| Titel |
Discharge estimation combining flow routing and occasional measurements of velocity |
| VerfasserIn |
G. Corato, T. Moramarco, T. Tucciarelli |
| 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 ; 15, no. 9 ; Nr. 15, no. 9 (2011-09-26), S.2979-2994 |
| Datensatznummer |
250012966
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| Publikation (Nr.) |
 copernicus.org/hess-15-2979-2011.pdf |
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| Zusammenfassung |
| A new procedure is proposed for estimating river discharge hydrographs
during flood events, using only water level data at a single gauged site, as
well as 1-D shallow water modelling and occasional maximum surface flow
velocity measurements. One-dimensional diffusive hydraulic model is used for
routing the recorded stage hydrograph in the channel reach considering
zero-diffusion downstream boundary condition. Based on synthetic tests
concerning a broad prismatic channel, the "suitable" reach length is
chosen in order to minimize the effect of the approximated downstream
boundary condition on the estimation of the upstream discharge hydrograph.
The Manning's roughness coefficient is calibrated by using occasional
instantaneous surface velocity measurements during the rising limb of flood
that are used to estimate instantaneous discharges by adopting, in the flow
area, a two-dimensional velocity distribution model. Several historical
events recorded in three gauged sites along the upper Tiber River, wherein
reliable rating curves are available, have been used for the validation. The
outcomes of the analysis can be summarized as follows: (1) the criterion
adopted for selecting the "suitable" channel length based on synthetic
test studies has proved to be reliable for field applications to three
gauged sites. Indeed, for each event a downstream reach length not more than
500 m is found to be sufficient, for a good performances of the hydraulic
model, thereby enabling the drastic reduction of river cross-sections data;
(2) the procedure for Manning's roughness coefficient calibration allowed for high
performance in discharge estimation just considering the observed water
levels and occasional measurements of maximum surface flow velocity during
the rising limb of flood. Indeed, errors in the peak discharge magnitude,
for the optimal calibration, were found not exceeding 5% for all events
observed in the three investigated gauged sections, while the Nash-Sutcliffe
efficiency was, on average, greater than 0.95. Therefore, the proposed
procedure well lend itself to be applied for: (1) the extrapolation of rating
curve over the field of velocity measurements (2) discharge estimations in
different cross sections during the same flood event using occasional
surface flow velocity measures carried out, for instance, by hand-held radar
sensors. |
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