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| Titel |
Frequent flash floods in southern Switzerland: Why? |
| VerfasserIn |
Luca Panziera, Curtis James, Urs Germann |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092311
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| Publikation (Nr.) |
 EGU/EGU2014-6642.pdf |
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| Zusammenfassung |
| This study investigates the causes of frequent flash floods observed in the Maggia River
catchment, a 900 km2 watershed located in southern Switzerland. During the heaviest
floods, river discharge rates can increase by as much as 1400 m3/s in less than 3
hours!
High-resolution volumetric radar data and sounding profiles are extensively used to
investigate the environmental conditions and mesoscale precipitation mechanisms producing
floods for the last 8 years in the catchment.
The events causing the highest discharge rates in the river are typically due to orographic
convection, which is absent from storm events that produce lower peak flow rates. During the
heaviest floods, individual convective cells are repeatedly advected over the Maggia
watershed, producing excessive rainfall and river discharge rates. At larger temporal
scales, precipitation patterns assume the form of quasi-stationary, elongated bands of
rainfall.
The results of this work provide a conceptual model for orographic convection
development in sheared flows, depicting a mechanism which is likely to be observed over
other mountainous chains of the world. |
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