Modèle global pluie-débit pour la prévision et la prédétermination des crues

Overall rain-flow model for flood forecasting and pre-determination

EDF, Ressources en Eau

Abstract

The water flow mechanisms in a catchment area are highly complex and detailed modelling of these mechanisms is obstructed by the problem of understanding the phenomena as well as that of gaining accurate knowledge of the many local sensitive parameters. Faced with this difficulty, and without wanting to cast doubt on the hope of future progress, one of the hydrologist's solutions to assist decision making in operational conditions, has been to develop simple models, dealing only with the main traits of the rain-flow transformation process. For example, those governing the evolution of the percentage of rain which flows away rapidly or the time dynamics of flood run-off. Here, with respect to these two aspects, we draw a parallel between the models retained by EDF for three different purposes: short term flood forecasting (DPFT), estimation of the probability of extreme floods (GRADEX) and continuous monitoring of water resources (MORDOR). Particular emphasis is placed on the way in which each of these models takes account of the move from normal to extreme conditions.