The Draix-Bleone observatory has been instrumented in the early 1980s to study water and sediment fluxes in a highly erodible mountainous environment. It is characterized by badland morphology with strong erosion rates and a mixed mountainous and mediterranean climate with winter frost and storm-induced floods. Several catchments of different sizes, vegetation cover and morphology are monitored including the Laval (86 ha), the Moulin (9 ha), the Roubine (1.3 ha) and the Francon (73 ha). The observatory also includes a neighbor catchment that has been reforested in the late XIXth century: the Brusquet, a larger catchment downstream: the Bouinenc (22 km2) and a neighbour catchment located on a different lithology: the Galabre (30km2). Water discharge, suspended and bedload sediment fluxes are monitored at a high-frequency at the outlet of each catchment. Precipitations, climatic data and soil properties are also measured across the observatory. More information at http://oredraixbleone.irstea.fr The Draix-Bleone observatory is part of the RBV network for the observation of the critical zone.