Cartographie de l'aléa pluviographique de la France

Abstract

Cemagref have developed the SHYPRE approach and its regionalized version SHYREG to assess the hydrological risk, anywhere on the hydrographical network. On the base of this method, a stochastic model of hourly rainfall was developed to reproduce the temporal characteristics of the observed rainfall, and to generate long rainfall time series, statistically equivalent to the observed chronicles. The modelling of the temporal characteristics of the rainfall leads to a hyper-exponential asymptote of the frequency distributions of the rains of various durations. Model regionalisation is based on daily rainfall characteristics. In metropolitan France, the regionalization leans on observations of practically 3000 precipitation gages. It leads in the fine spatial knowledge (1 km2 pixel) of the characteristics of the hourly rainfall model. So the model can be used and leads to a Geographical Information System of rainfall risk, which supplies an estimation of rains on the whole range of the frequencies, for 1 to 72-hours durations. Beyond the obvious operational interest, the analysis of the results obtained shows the pertinence of this approach and its robustness.