Cartography of Extreme Rainfall and Their Relationship with Topography in the French Alps

Abstract

The extreme rains of court duration are the principal cause of brutal and catastrophic flood that can be produced on a nombre of smal bassin on the french Alps. This study consists on a cartography of extraim values of pluviometric parametres, as a Gradex, rains with a period of 10 years, 100 years and 1000 years, for six steps of time (1 h, 2 h, 3 h, 6 h, 12 h, 24 h); and Montana parameter on the french Alps where the orographic effect is big and the estimation of reliables values on unmonitored site using data of environmental stations need the introduction of morphometric informations. The areA study covers a surface of 250 km × 450 km and dispose of 65 oluviometrics stations of average durations between 30 and 35 years. This study has been done on two steps, first we have done a presentation of a region by a relief and a climate, second, we have displayed pluviometrics systems using ACP method. The idea based on AURELHY method (Analysing Using Relief for HYdrometeology) that consists to intervene the local topography by a lineair regression and analysing by kriging the residu of the regression has been used for this cartography.