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Benefits and limitations of data assimilation for discharge forecasting using an event-based rainfall–runoff model

Coustau, Mathieu and Ricci, Sophie and Borrell-Estupina, Valérie and Bouvier, Christophe and Thual, Olivier Benefits and limitations of data assimilation for discharge forecasting using an event-based rainfall–runoff model. (2013) Natural Hazards and Earth System Science, 13 (3). 583-596. ISSN 1684-9981

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Official URL: http://dx.doi.org/10.5194/nhess-13-583-2013

Abstract

Mediterranean catchments in southern France are threatened by potentially devastating fast floods which are difficult to anticipate. In order to improve the skill of rainfall-runoff models in predicting such flash floods, hydrologists use data assimilation techniques to provide real-time updates of the model using observational data. This approach seeks to reduce the uncertainties present in different components of the hydrological model (forcing, parameters or state variables) in order to minimize the error in simulated discharges. This article presents a data assimilation procedure, the best linear unbiased estimator (BLUE), used with the goal of improving the peak discharge predictions generated by an event-based hydrological model Soil Conservation Service lag and route (SCS-LR). For a given prediction date, selected model inputs are corrected by assimilating discharge data observed at the basin outlet. This study is conducted on the Lez Mediterranean basin in southern France. The key objectives of this article are (i) to select the parameter(s) which allow for the most efficient and reliable correction of the simulated discharges, (ii) to demonstrate the impact of the correction of the initial condition upon simulated discharges, and (iii) to identify and understand conditions in which this technique fails to improve the forecast skill. The correction of the initial moisture deficit of the soil reservoir proves to be the most efficient control parameter for adjusting the peak discharge. Using data assimilation, this correction leads to an average of 12% improvement in the flood peak magnitude forecast in 75% of cases. The investigation of the other 25% of cases points out a number of precautions for the appropriate use of this data assimilation procedure.

Item Type:Article
Additional Information:Thanks to European Geosciences Union editor.The definitive version is available at http://www.nat-hazards-earth-syst-sci.net The original PDF of the article can be found at http://dx.doi.org/10.5194/nhess-13-583-2013
HAL Id:hal-00808478
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut de Recherche pour le Développement - IRD (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Université de Montpellier 1 (FRANCE)
Other partners > Université de Montpellier 2 (FRANCE)
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Deposited On:22 Mar 2013 13:12

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