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| Titel |
Simulation of torrential rain as a means for assessment of surface runoff coefficients and calculation of recurrent design events in alpine catchments |
| VerfasserIn |
Gerhard Markart, Bernhard Kohl, Bernadette Sotier, Klaus Klebinder, Thomas Schauer, Günther Bunza |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038508
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| Zusammenfassung |
| Simulation of heavy rain is an established method for studying infiltration characteristics,
runoff and erosion behaviour in alpine catchments. Accordingly for characterization and
differentiation of various runoff producing areas in alpine catchments transportable spray
irrigation installations for large plots have been developed at the BFW, Department of Natural
Hazards and Alpine Timberline, in Innsbruck, Austria. One installation has been
designed for assessment of surface runoff coefficients under convective torrential
rain with applicable precipitation intensities between 30 and 120 mm*h-1 and
a plot size between 50 and 100 m2. The second device is used for simulation of
persistent rain events (rain intensity about 10 mm*h-1, plot size: 400-1200 m2). Very
reasonable results have been achieved during the comparison with spray irrigations
from other institutions (e.g. Bavarian Environmental Agency in Munich) in the
field.
Rain simulations at BFW are mostly combined with comprehensive additional
investigations on land-use, vegetation cover, soil physical characteristics, soil humidity,
hydrogeology and other features of the test-sites. This allows proper interpretation of the
achieved runoff data. At the moment results from more than 280 rain simulations are
available from about 25 catchments / regions of the Eastern Alps at the BFW.
Results show that the surface runoff coefficient, when runoff is constant at the test site
(Ïconst) increases only slightly between rain intensities from 30 to 120 mm*h-1
(increment is 6%). Therefore Ïconst shall be used for assessment of runoff behaviour of
runoff contributing areas, because it is less dependent form system conditions than
Ïtot.
BFW-data have been consolidated with results of the LfU (Bavarian Environmental
Agency in Munich) in a data base and formed the basis for the development of a simple code
of practice for assessment of surface runoff coefficients in torrential rain. The manual
is freely available under: http://bfw.ac.at/rz/bfwcms.web?dok=4342 (in German
language).
The runoff contributing areas delineated by use of the manual in the field can be compiled
in digital surface runoff coefficient maps and surface roughness maps. These maps in Austria
form the basis for calculation of recurrent design events by use of precipitation/runoff models
(P/R-models) like ZEMOKOST (optimized runtime method after Zeller = ZEller MOdified
by KOhl and STepanek) or HEC-HMS. The result is substantial information on runoff
disposition in each sub-catchment and hydrographs showing peak runoff and runoff
freight.
The code of practice for assessment of surface runoff coefficients has become the
standard procedure in Austria to derive input parameters for P/R-models in practice. Recent
investigations done at the Institute of Geography at the University of Berne show that the
code of practice is suitable for application in catchments at the northern edge of the Swiss
Alps too. |
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