Small agricultural catchment (320 ha) with 30 years of data to study impact of climate change and agricultural practices on soil erosion, weathering rate and river fluxes. Continuous measurements with sensor: river discharge, Temperature, pH, conductivity, turbidity, dissolved oxygen, nitrate Weekly samples and high resolution sampling during storm runoff: major cations and anions, alkalinity, pH, dissolved silica, conductivity, total suspended solids, stable isotopes (13C of DIC, 2H and 18O of H2O, 15N of nitrates), heavy metals, some pesticide molecules Climatological station, rain collector for precipitation chemistry, soil solution station with lysimetric plate at different depths. Continuous measurement since 2004 of CO2, N2O, water vapor, energy exchange in the soil-vegetation-atmosphere continuum thanks to Eddycovariance and closed chamber methodologies (see OZCAR-RI Regional Spatial Observatory in the South West France contribution) Collaboration with the Aurade farmer association for fertilizer and pesticide inputs, cultivation, agricultural practices... Aurade experimental catchment and flux site are an international field site of the Critical Zone Exploration Network CZEN and of ICOS network, a field site of the French Research Infrastructure OZCAR and it is also a site of the French LTSER ZA PYGAR "Zone Atelier Pyrénées-Garonne". and a regional Platform of Research and Innovation-Midi Pyrénées.