Assessment of probabilistic areal reduction factors of precipitations for the entire French territory with gridded rainfall data
Estimation de l'abattement probabiliste des pluies sur l'ensemble du territoire français à l'aide de pluies spatialisées
Fouchier, C. ; Maire, A. ; Arnaud, P. ; Cantet, P. ; Odry, J.
Type de document
Affiliation de l'auteur
IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA ; IRSTEA AIX EN PROVENCE UR RECOVER FRA
Résumé / Abstract
The starting point of our study was the availability of maps of rainfall quantiles available for the entire French mainland territory at the spatial resolution of 1 km². These maps display the rainfall amounts estimated for different rainfall durations (from 15 minutes to 72 hours) and different return periods (from 2 years up to 1 000 years). They are provided by a regionalized stochastic hourly point rainfall generator, the SHYREG method which was previously developed by Irstea. Being calibrated independently on numerous raingauges data (with an average density across the country of 1 raingauge per 200 km²), this method suffers from a limitation common to point-process rainfall generators: it can only reproduce point rainfall patterns and has no capacity to generate rainfall fields. It can’t hence provide areal rainfall quantiles, the estimation of the latter being however needed for the construction of design rainfall or for the diagnostic of observed events. One means of bridging this gap between our local rainfall quantiles and areal rainfall quantiles is given by the concept of probabilistic areal reduction factors of rainfall (ARF). This concept enables to estimate areal rainfall of a particular frequency within a certain amount of time from point rainfalls of the same frequency and duration. Assessing such ARF for the whole French territory is of particular interest since it should allow us to compute areal rainfall quantiles, and eventually watershed rainfall quantiles, by using the already available grids of statistical point rainfall of the SHYREG method.
EGU General Assembly 2016, 17/04/2016 - 22/04/2016, Vienna, AUT