A probabilistic view on the August 2005 floods in the upper Rhine catchment

Appropriate precautions in the case of flood occurrence often require long lead times (several days) in hydrological forecasting. This in turn implies large uncertainties that are mainly inherited from the meteorological precipitation forecast. Here we present a case study of the extreme flood event...

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Main Authors: S. Jaun, B. Ahrens, A. Walser, T. Ewen, C. Schär
Format: Article
Language:English
Published: Copernicus Publications 2008-04-01
Series:Natural Hazards and Earth System Sciences
Online Access:http://www.nat-hazards-earth-syst-sci.net/8/281/2008/nhess-8-281-2008.pdf
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author S. Jaun
B. Ahrens
A. Walser
T. Ewen
C. Schär
author_facet S. Jaun
B. Ahrens
A. Walser
T. Ewen
C. Schär
author_sort S. Jaun
collection DOAJ
description Appropriate precautions in the case of flood occurrence often require long lead times (several days) in hydrological forecasting. This in turn implies large uncertainties that are mainly inherited from the meteorological precipitation forecast. Here we present a case study of the extreme flood event of August 2005 in the Swiss part of the Rhine catchment (total area 34 550 km<sup>2</sup>). This event caused tremendous damage and was associated with precipitation amounts and flood peaks with return periods beyond 10 to 100 years. To deal with the underlying intrinsic predictability limitations, a probabilistic forecasting system is tested, which is based on a hydrological-meteorological ensemble prediction system. The meteorological component of the system is the operational limited-area COSMO-LEPS that downscales the ECMWF ensemble prediction system to a horizontal resolution of 10 km, while the hydrological component is based on the semi-distributed hydrological model PREVAH with a spatial resolution of 500 m. We document the setup of the coupled system and assess its performance for the flood event under consideration. <br><br> We show that the probabilistic meteorological-hydrological ensemble prediction chain is quite effective and provides additional guidance for extreme event forecasting, in comparison to a purely deterministic forecasting system. For the case studied, it is also shown that most of the benefits of the probabilistic approach may be realized with a comparatively small ensemble size of 10 members.
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spelling doaj.art-b99c45a9378d4e3e8528bd5368891e762022-12-21T20:39:09ZengCopernicus PublicationsNatural Hazards and Earth System Sciences1561-86331684-99812008-04-0182281291A probabilistic view on the August 2005 floods in the upper Rhine catchmentS. JaunB. AhrensA. WalserT. EwenC. SchärAppropriate precautions in the case of flood occurrence often require long lead times (several days) in hydrological forecasting. This in turn implies large uncertainties that are mainly inherited from the meteorological precipitation forecast. Here we present a case study of the extreme flood event of August 2005 in the Swiss part of the Rhine catchment (total area 34 550 km<sup>2</sup>). This event caused tremendous damage and was associated with precipitation amounts and flood peaks with return periods beyond 10 to 100 years. To deal with the underlying intrinsic predictability limitations, a probabilistic forecasting system is tested, which is based on a hydrological-meteorological ensemble prediction system. The meteorological component of the system is the operational limited-area COSMO-LEPS that downscales the ECMWF ensemble prediction system to a horizontal resolution of 10 km, while the hydrological component is based on the semi-distributed hydrological model PREVAH with a spatial resolution of 500 m. We document the setup of the coupled system and assess its performance for the flood event under consideration. <br><br> We show that the probabilistic meteorological-hydrological ensemble prediction chain is quite effective and provides additional guidance for extreme event forecasting, in comparison to a purely deterministic forecasting system. For the case studied, it is also shown that most of the benefits of the probabilistic approach may be realized with a comparatively small ensemble size of 10 members.http://www.nat-hazards-earth-syst-sci.net/8/281/2008/nhess-8-281-2008.pdf
spellingShingle S. Jaun
B. Ahrens
A. Walser
T. Ewen
C. Schär
A probabilistic view on the August 2005 floods in the upper Rhine catchment
Natural Hazards and Earth System Sciences
title A probabilistic view on the August 2005 floods in the upper Rhine catchment
title_full A probabilistic view on the August 2005 floods in the upper Rhine catchment
title_fullStr A probabilistic view on the August 2005 floods in the upper Rhine catchment
title_full_unstemmed A probabilistic view on the August 2005 floods in the upper Rhine catchment
title_short A probabilistic view on the August 2005 floods in the upper Rhine catchment
title_sort probabilistic view on the august 2005 floods in the upper rhine catchment
url http://www.nat-hazards-earth-syst-sci.net/8/281/2008/nhess-8-281-2008.pdf
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