The Bras-David river is located on Basse-Terre Island (Guadeloupe archipelago, lesser Antilles arc). This volcanic island results from the ongoing subduction of the Atlantic plate under the Caribbean plate. The Bras-David river drains a watershed of 19 km2 on the windward side of the active Soufrière volcano. The catchment is essentially composed of Pleistocene andesitic and dacitic formations, covered by a thick ferralitic soil. The latter consists of highly weathered volcanoclastic debris flows containing rocky clasts at various stages of weathering. Vegetation is mainly dominated by tropical rainforest. The hydrologic regime is torrential: flow rate is characterized by abrupt variations due to tropical rains. Storms and hurricanes are particularly frequent during the rainy season from june to january.

The Capesterre river is located on Basse-Terre Island (Guadeloupe archipelago, lesser Antilles arc). This volcanic island results from the ongoing subduction of the Atlantic plate under the Caribbean plate. Capesterre drains a watershed of 16.4 km2 located on the windward side of the active Soufrière volcano. The Capesterre catchment, mainly composed of lava and pyroclastic flows aged from 600 to 400 ky, is characterized by rather thin soils, typically ranging from 0.5 to 2 meters. Vegetation is dominated by tropical rainforest. The hydrologic regime is torrential: flow rate is characterized by abrupt variations due to tropical rains. Storms and hurricanes are particularly frequent during the rainy season from june to january.

The AAA-LTER platform focuses on agricultural and urban landscape The objective of the proposed LTSER structure is to provide an internationally open, attractive and recognized scientific observatory of human/nature interactions. Through its representativeness of environmental issues of Atlantic terrestrial and aquatic landscapes and the complementarity of its eLTER sites, the AAA-LTSER is a unique showcase for decision makers to help them in defining regional decision frameworks and sustainable policies, and to promote technical and social innovation as well as science education. The AAA-LTSER embraces regional social-ecological dimensions whose diversity of landscape use and planning covers a unique set of interconnected aquatic and terrestrial systems. lt concentrates multiples supports and cofunding from the European Union, the State, the Brittany region and local institutions to improve and maintain high density of sensors, equipment and social studies that are crucial for better understanding human/nature interactions and train the next generation of scientists to work at these interfaces in inter- and trans-disciplinary approaches. To cover the major regional environments and interfaces (continent/ocean, urban/rural, subsurface/surface), the AAA-LTSER platform is founded on existing and complementary sites. They represent the different terrestrial, transitional and marine landscape structures, features and dynamics that shape this intensive anthropogenic region, and their related social-ecological issues. All these sites involve end-users and policy makers seeking for advanced understanding of social and ecological interactions and the definition, validation and promotion of sustainable policies.

The Galabre site is part of Draix-Bleone observatory, located in the French South Alps, upstream of Digne, on the right side of the Bleone river. The hydrosedimentary station of La Robine-sur-Galabre was created in 2008 to measure water of sediment fluxes from the Galabre catchment, 20 km2. This catchment integrates a diversity of lithologies and land use that are characteristic of the Pre-Alps. The climate is mountainous and Mediterranean. The site is characterized by intense erosion and intermittent sediment fluxes. The variables that are monitored on the long-term include rainfall and meteorology, high-frequency water discharge and suspended sediment concentration (10 minutes), some physico-chemical properties of stream water and sediments.

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.

Draix site is part of Draix-Bleone observatory, located in the French South Alps, upstream of Digne, on the left side of the Bleone. Draix site was equipped in 1983 to study mountain erosion and sediment transport. It is composed of 4 catchments, which are equipped to measure water and sediment fluxes, at spatial scales ranging from 0.001 km2 to 1 km2, with contrasted land cover. These catchments are entirely situated on black marls that are very sensitive to weathering and erosion, resulting into a badland topography. One catchment was reforested at the end of the XIXth century whereas the other are mostly denuded. This site is characterized by intense erosion and intermittent sediment fluxes. The variables that are monitored on the long-term include rainfall and meteorology, high-frequency water discharge and suspended sediment concentration (1-10 minutes), event-scale bedload transport, and some physico-chemical properties of stream water and sediments.

Hydrometeorological observations within 6 embedded catchments (from 0.3 to 3.9 km2). Mediterranean climate with heavy rainfall and flash floods in automn. The geology is mainly granite. The land use is mainly forest. This site is typical of the Cévennes region. More information at http://www.ohmcv.fr

The Bassin de la Rivière des Pluies is located on Réunion Island (French Overseas, Indian Ocean). This volcanic island results from the emission of basaltic products from the Réunion hotspot that initiated 65 Myrs ago with the development of the Deccan traps. Rivière des Pluies drains a watershed of 46 km2 located on the windward side of the dormant Piton des Neiges volcano, from 2276 msl to the sea shore. The Rivière des Pluies catchment is mainly composed of lava flows and breccias aged from 1.4 Ma to 200 ky. The overall watershed is made of a main canyon deeply incised in the volcano flank and a large planeze covered by the deposits of the last explosive eruptions of Piton des Neiges. The combined action of the vegetation and alteration along a strong altimetric gradient produced a wide range of soils typically ranging from 0.5 to 6 meters. Vegetation is dominated by tropical rainforest. The hydrologic regime is torrential: flow rate is characterized by abrupt variations due to tropical rains. Storms and cyclones only occur during the rainy season from december to april.

Hydrometeorological and biogeochemical observations within 5 embedded catchments (from 0.2 to 14.5 km2). Alpine Mediterranean climate with heavy rainfall and flash floods in automn. The geology is mainly granite. The land use is mainly grassland and forest. More information at http://www.ohmcv.fr

Hydrometeorological observations within 3 embedded catchments (0.9, 2.6 and 14.5 km2). Mediterranean climate with heavy rainfall and flash floods in automn. The geology is mainly shale. The land use is mainly forest. This site is typical of the Cévennes region. More information at http://www.ohmcv.fr