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| Titel |
Extreme multi-basin fluvial flows and their relationship to extra-tropical cyclones |
| VerfasserIn |
Paolo De Luca, John K. Hillier, Robert L. Wilby, Nevil W. Quinn, Shaun Harrigan |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138780
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| Publikation (Nr.) |
 EGU/EGU2017-1901.pdf |
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| Zusammenfassung |
| Fluvial floods are typically investigated as ‘events’ at the single basin scale, thereby
implicitly assuming that severe flooding impacts each catchment independently from
those nearby. A statistical analysis of the spatio-temporal characteristics of extreme
flows in Great Britain (GB), during 1975-2014, is presented. These observations
deepen understanding of the processes leading to multi-basin floods and present
helpful insights for contingency planning and emergency responders. The largest
multi-basin peak flow events within different time windows were identified by counting
the number of coincident annual maximum river peak flows (AMAX) across 261
non-nested catchments, using search windows of 1 to 19 days. This showed that up
to 107 basins reached their AMAX within the same plateauing 13-day window,
draining a total area equivalent to ∼46% of the overall basins considered, which
is an equivalent fraction of ∼27% of Great Britain. Such episodes are typically
associated with persistent cyclonic atmospheric circulation and saturated ground,
combined with short hydrological response times (<48 h) from large contributing
basins. The most spatially extensive episodes also tend to coincide with the most
severe gales (i.e. extra-tropical cyclones) on a ±0-13 day time-scale. The analysis
suggests that multi-basin peak flow events can be characterised by concurrent peak
flow AMAX and that the most extreme are driven by very severe gales (VSG).
This has implications for emergency response including planning for combined
flood-wind impacts (on for example power and communication systems), meaning
that the emergency preparedness need to be reorganised in order to face this peril. |
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