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combination of uniformly distributed and point inflows is used. In this case,model performance was not very sensitive to this factor and the inclusion of570two or three tributaries appeared sufficient for simulating flow on the mainchannel. In contrast, this selection can be much more difficult with pointinflow models because a large number of combinations need to be tested toidentify the optimal one.• The simulation on the main channel differed from the simulation on one575tributary: the overall performance is higher on the main channel and requirestel-00392240, version 1 - 5 Jun 2009580585590a lesser degree of lateral inflow resolution. The best performance on thetributary was obtained when the highest number of tributaries were includedin the model.The authors acknowledge that the methods analysed in this article should betested on a larger number of catchments to reach more general conclusions.The extension of these results to a database of 50 catchments located in Francewas investigated by Lerat (2009), who obtained similar conclusions, to bereported in the near future.This work opens several perspectives that may clarify the methods used incoupling rainfall-runoff models and hydraulic models. First, we used a lineariseddiffusive wave model based on a simplification of the Saint-Venantequation system. The methods presented in this paper should now be appliedwith a fully dynamic model. Second, we did not investigate the impact ofrainfall input quality and the complexity of model parameterisation. Finally,the long-term objective of this study was to propose robust methods to applycoupled models to flood forecasting. This paper only covered the simulationmode without using assimilation algorithms. The forecasting mode will be thenext step and the results will be reported in due course.27