 |
| Titel |
Synthetic Hydrograph Generator for Reservoirs: Potential and Limitations |
| VerfasserIn |
Jens Bender, Christoph Mudersbach, Jürgen Jensen |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051715
|
|
|
|
|
|
| Zusammenfassung |
| The hydraulic design of dams and reservoirs still represents one of the most important tasks
in hydraulic engineering, not least because of the high destruction potential in case of a
structural dam failure.
The revised German dam standard DIN 19700 (2004) postulates for the design of
reservoirs and flood control basins the use of hydrographs of extreme events with occurrence
probabilities of up to T = 10.000 years. Hence, a large variety of different hydrographs has to
be considered in the design since not only the peak discharge is of major interest but also the
flood volume and the shape of the hydrograph.
A stochastic flood hydrograph generator was programmed and applied to the
Obernau Reservoir (Germany) in order to simulate extreme flood events, based on the
German guideline “Generation of Design Hydrographs following DIN 19700 in North
Rhine-Westphalia”, published by the Ministry of Environment of North Rhine-Westphalia
(MUNLV). The program uses historical stream flow data of representing tributaries to the
reservoir as the only input dataset. The shapes of recorded flood hydrographs can be
described mathematically by 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 for
the recession period (mab).
Fitting distribution functions to all samples allows for generating any number of synthetic
flood events by the random walk method, e.g. 10.000.
For simply shaped hydrographs, the program produces usable results. However, in case of
shapes that are more complex, the method reaches its limits. Thus, multi-peak events cannot
be illustrated adequately as well as slowly rising flood events. Another limitation of this
method is the insufficiency to describe and simulate flood events where the peak flow remains
almost constant for a specified time period. Especially those events can lead to
severe loads for the spillway and the dam structure. The extension of the method
by introducing a fifth parameter called peak flow duration (tS) may resolve this
limitation.
The results, which will be presented, will focus on the potential of this flood hydrograph
simulation method and show limitations as well as approaches to improve the overall results. |
|
|
|
|
|
|