The VCG platform is an area of molassic foothills, covering the Louge, Touch and Save watersheds; it is bounded to the south, east and north by the Garonne. The platform is located inside the Zone Atelier Pyrénées-Garonne, and it includes the Auradé watershed site.

It is located in the region of the Grand Causses, south of the Massif Central. The karstic aquifer of Durzon represents a surface of 100 km² which feeds the spring of Durzon. This spring supplies the drinking water of the Aveyron part of Larzac. The observatory has a set of sites dedicated to gravimetric, inclinometric and hydro-geodesic observations, as well as a flow tower for evapotranspiration measurements.

The ZA PYGAR covers the whole Garonne river basin up to the upper part of the Gironde estuary (La Reole station). Within this territory, research is structured around 4 main sites: the Pyrénées mountains, covering the upstream part of the Garonne river basin (PYRénées site), the farmland of the foothills of the Pyrénées (Vallées et Coteaux de Gascogne site), the Garonne river (Axe Fluvial Garonne site) and the basin of two tributaries of the Garonne river in the Massif Central moutains (Aveyron-Viaur site).