SHYREG: a methodology for a regional assessment of flood discharge. Application in the French mediterranean area

Abstract

SHYREG is a method developed for the regional knowledge of the flood discharges over different durations and for different return periods. The methodology consists of a hourly rainfall generator associated with a simple rainfall - runoff modelisation. It enables the simulation of long-term discharge data sets. Frequency distribution are drawn from these simulated series, thus allowing the evaluation of the discharge quantiles. This information is mapped with a resolution of 1 km2. The estimation of the discharge quantiles for a river basin requires to synthesise this continuous information. This led us to introduce the concept of a Statistical Transfer Function (FTS : Fonction de Transfert Statistique). It is then possible to give an estimation of the reference flood discharges in any point of the hydrographic network of the studied area. On the French Mediterranean Area, this regional methodology is based upon more than 500 raingauges and 220 watersheds. It leads to a good restitution of the discharge quantiles estimated from the observed series for return periods ranging between 2 and 100 years.