1. Background information

The term flash flood was proposed by the International Association of Hydrological Sciences . It corresponds to the following definition: "a flood whose onset is sudden, often difficult to predict, with a rapid rise time and relatively high specific discharge. These flash floods are generally linked to intense rainfall events and often occur in moderate-sized basins". In reality, this translates into episodes where the rapidity of response stems partly from the size of the catchment areas concerned, generally less than a few hundred km ^...