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| Titel |
An Enhanced Approach to Generate Synthetic Hydrographs with Low Probability of Occurrence |
| VerfasserIn |
J. Bender, J. Jensen |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067128
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| Zusammenfassung |
| Extreme flood hydrographs are required for many different issues in hydraulic engineering
applications. As an alternative to rainfall runoff models, the Flood Characteristic
Simulation, based on the German guideline “Generation of Design Hydrographs
following the DIN 19700 in North Rhine-Westphalia”, published by the Ministry of
Environment of North Rhine-Westphalia (MUNLV) provides the opportunity to
generate synthetic hydrographs solely based on recorded discharge time series.
The shapes of recorded flood hydrographs can be described mathematically by the
combination of two analytic functions: The Kozeny Function for the rising part of the
flood event and a parabolic function for the recession part. Overall, four parameters
are used to describe the hydrograph: the time period of increasing discharge (tA),
the peak run-off (QS), the dimensionless shape parameters for the rising period
(man) and the recession period (mab). Fitting distribution functions to all samples
will allow generation of any number (e.g. 10,000) of synthetic flood events by the
random walk method. The model produces reasonable results for simple-shaped
hydrographs, i.e. single peak hydrographs. However, application of this method shows the
deficiency of not being able to simulate flood events with almost constant peak
flows over a specific time period. Thus, considering the peak flow duration tP in the
simulation seems to be desirable. By extending the existing simulation method
with the time duration tP as a fifth parameter the overall results are expected to be
improved.
In this study, results of the enhanced hydrograph generator, considering tP, will be
presented. In Bender & Jensen (2012, accepted) the classical as well as the enhanced method
have been applied to a case study in Germany. Using the enhanced method the results show
that in particular the upper part of the hydrographs can be simulated substantially better. In
order to quantify the improvements all recorded hydrographs of a 38-year time series have
been parameterized and re-simulated using both methods. Correlating the simulated flood
volumes with the recorded flood volumes then provides a classification of the improvement.
The results show that the enhanced method leads up to a 20 % higher correlation
coefficient compared to the classical method with only little additional effort for the user. |
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