HESS Hydrology and Earth System Sciences HESS Hydrol. Earth Syst. Sci. 1607-7938 Copernicus Publications Göttingen, Germany 10.5194/hess-13-819-2009 How crucial is it to account for the antecedent moisture conditions in flood forecasting? Comparison of event-based and continuous approaches on 178 catchments Berthet L. 1 2 Andréassian V. 1 Perrin C. 1 Javelle P. 3 Cemagref, Hydrosystems and Bioprocesses Research Unit Antony, France AgroParisTech ENGREF, 19 avenue du Maine, 75732 Paris, France Cemagref, Hydrology and Hydraulic Works Research Unit, Aix-en-Provence, France 18 06 2009 13 6 819 831 Copyright: © 2009 L. Berthet et al. 2009 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://hess.copernicus.org/articles/13/819/2009/hess-13-819-2009.html The full text article is available as a PDF file from https://hess.copernicus.org/articles/13/819/2009/hess-13-819-2009.pdf

This paper compares event-based and continuous hydrological modelling approaches for real-time forecasting of river flows. Both approaches are compared using a lumped hydrologic model (whose structure includes a soil moisture accounting (SMA) store and a routing store) on a data set of 178 French catchments. The main focus of this study was to investigate the actual impact of soil moisture initial conditions on the performance of flood forecasting models and the possible compensations with updating techniques. The rainfall-runoff model assimilation technique we used does not impact the SMA component of the model but only its routing part. Tests were made by running the SMA store continuously or on event basis, everything else being equal. The results show that the continuous approach remains the reference to ensure good forecasting performances. We show, however, that the possibility to assimilate the last observed flow considerably reduces the differences in performance. Last, we present a robust alternative to initialize the SMA store where continuous approaches are impossible because of data availability problems.

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