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| Titel |
Characteristics of the extreme rainfall event and consequent flash floods in W Slovenia in September 2007 |
| VerfasserIn |
S. Rusjan, M. Kobold, M. Mikoš  |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 9, no. 3 ; Nr. 9, no. 3 (2009-06-23), S.947-956 |
| Datensatznummer |
250006801
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| Publikation (Nr.) |
 copernicus.org/nhess-9-947-2009.pdf |
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| Zusammenfassung |
| During a weather front that passed over large parts of Slovenia on
18.9.2007, extreme rainfall events were triggered causing several severe
flash floods with six casualties. Out of 210 municipalities in Slovenia, 60
were reporting flood damages, and the total economic flood damage was later
estimated at close to 200 million Euro; highest damage was claimed by
Železniki municipality in NW Slovenia. The main purpose of the study
presented in this paper was to put together available meteorological and
hydrological data in order to get better insight into temporal and spatial
dynamics and variability of the flash flood event along the Selška Sora
River flowing through the town of Železniki. The weather forecast by the
Environmental Agency of the Republic of Slovenia (ARSO) lead to early
warning of floodings but has underestimated rainfall amounts by a factor of
2. Also meteorological radar underestimated ground rainfall as much as by 50%.
During that day, in many rainfall gauging stations operated by ARSO in
the area under investigation, extreme rainfall amounts were measured, e.g. 303 mm
in 24 h or 157 mm in 2 h. Some of the measured rainfall
amounts were the highest registered amounts in Slovenia so far. Statistical
analysis using Gumble distribution was performed and rainfall return periods
were estimated. When assessing rainfall return periods, a question of the
sampling error as a consequence of short rainfall records used was raised.
Furthermore, measured rainfall data were used to reconstruct hydrographs on
selected water stations along the Selška Sora River. The cumulative
areal precipitation for the Selška Sora River catchment upstream of
Železniki amounted to 219 mm, while the modeled effective precipitation
used to simulate the hydrograph peak was only 57 mm. The modeled direct
runoff coefficient therefore amounts to 0.26. Surprisingly low value is
mainly caused by the applied unit hydrograph method that seeks to meet the
peak discharge rather than hydrograph volume. However, the spatial
distribution of the rainfall in the area was highly variable and present
spatial positioning of rain gauges is obviously inadequate for proper
representation of the actual spatial amount of rainfall. The study confirmed
that post-flood investigation should focus on discharges and hydrological
response of the catchment rather than simply analyzing statistical
characteristics of rainfall. |
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