Résumé
There is a need to improve rainfall runoff modelling of flash floods in the Mediterranean region, in order to better predict these extreme hydrological events. In this study, the efficiency of the distributed SCS-LR rainfall runoff model is evaluated, using either the mean areal rainfall or spatially distributed rainfall over the watershed as inputs of the model. The distributed SCS-LR model is an event-based model accounting for four parameters. The efficiency of the model using either averaged or spatial rainfall as inputs is considered through the simulation of flood events, with fixed or calibrated model parameters for each event. A total of 30 flood events that occurred in the Gardon River (525 km(2)) located in the Cevennes region (southern France) were modelled. When both runoff and routing parameters are identical, the model is shown to underestimate the peak flows if using mean areal rainfall patterns instead of spatial rainfall patterns. Runoff volumes can also be underestimated in the case of highly variable rainfall occurring in dry soil conditions. The recalibration of the model is able to reduce some of the bias in the simulations. Nevertheless, as shown in the present study, not considering the spatial patterns of rainfall is leading to an increase in the variability of the model parameters. Thereby, the parameter estimation could be difficult with averaged rainfall in further applications of the model for operational purposes. The rainfall patterns have an impact on the parameterization of the model, depending on the rainfall spatial variation coefficient and the initial moisture of the soil. Accounting for the spatial pattern of the rainfall can improve the efficiency of the model, without increasing its complexity.