PIAHS Proceedings of the International Association of Hydrological Sciences PIAHS Proc. IAHS 2199-899X IAHS Press Göttingen, Germany 10.5194/piahs-364-3-2014 Variational data assimilation with the YAO platform for hydrological forecasting Abbaris A. 1 Dakhlaoui H. 3 2 Thiria S. 1 Bargaoui Z. 2 LOCEAN, Université Pierre et Marie Curie, Institut Pierre Simon Laplace, 4, place Jussieu 75252 Paris Cedex 05, France LMHE, Université Tunis El-Manar, Ecole Nationale d’Ingénieurs de Tunis, BP 37, 1003 Tunis le Belvédère, Tunisia ENAU, Université de Carthage, 20 Rue El Qods, 2026 Sidi Bou Saïd, Tunis, Tunisia 16 09 2014 364 3 8 Copyright: © 2014 A. Abbaris et al. 2014 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://piahs.copernicus.org/articles/364/3/2014/piahs-364-3-2014.html The full text article is available as a PDF file from https://piahs.copernicus.org/articles/364/3/2014/piahs-364-3-2014.pdf

In this study data assimilation based on variational assimilation was implemented with the HBV hydrological model using the YAO platform of University Pierre and Marie Curie (France). The principle of the variational assimilation is to consider the model state variables as control variables and optimise them by minimizing a cost function measuring the disagreement between observations and model simulations. The variational assimilation is used for the hydrological forecasting. In this case four state variables of the rainfall–runoff model HBV (those related to soil water content in the water balance tank and to water contents in rooting tanks) are considered as control variables. They were updated through the 4D-VAR procedure using daily discharge incoming information. The Serein basin in France was studied and a high level of forecasting accuracy was obtained with variational assimilation allowing flood anticipation.