 |
| Titel |
An efficient hybrid causative event-based approach for deriving the annual flood frequency distribution |
| VerfasserIn |
Mark Thyer, Jing Li, Martin Lambert, George Kuczera, Andrew Metcalfe |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108705
|
| Publikation (Nr.) |
 EGU/EGU2015-8473.pdf |
|
|
|
|
|
| Zusammenfassung |
| Flood extremes are driven by highly variable and complex climatic and hydrological
processes. Derived flood frequency methods are often used to predict the flood frequency
distribution (FFD) because they can provide predictions in ungauged catchments and evaluate
the impact of land-use or climate change. This study presents recent work on development of
a new derived flood frequency method called the hybrid causative events (HCE)
approach. The advantage of the HCE approach is that it combines the accuracy of the
continuous simulation approach with the computational efficiency of the event-based
approaches.
Derived flood frequency methods, can be divided into two classes. Event-based
approaches provide fast estimation, but can also lead to prediction bias due to limitations of
inherent assumptions required for obtaining input information (rainfall and catchment
wetness) for events that cause large floods. Continuous simulation produces more accurate
predictions, however, at the cost of massive computational time. The HCE method uses a
short continuous simulation to provide inputs for a rainfall-runoff model running in an
event-based fashion. A proof-of-concept pilot study that the HCE produces estimates of the
flood frequency distribution with similar accuracy as the continuous simulation, but with
dramatically reduced computation time.
Recent work incorporated seasonality into the HCE approach and evaluated with a more
realistic set of eight sites from a wide range of climate zones, typical of Australia, using a
virtual catchment approach. The seasonal hybrid-CE provided accurate predictions of the
FFD for all sites. Comparison with the existing non-seasonal hybrid-CE showed that for some
sites the non-seasonal hybrid-CE significantly over-predicted the FFD. Analysis of the
underlying cause of whether a site had a high, low or no need to use seasonality found it was
based on a combination of reasons, that were difficult to predict apriori. Hence
it is recommended that the seasonal hybrid-CE be used as it provided accurate
predictions for all sites. The evaluation of the HCE on a wide range of climatology’s,
including Mediterranean, temperate, sub-tropical/tropical and desert provide greater
confidence that it provides an accurate and efficient method for predicting the FFD. |
|
|
|
|
|
|