Fontaine de Vaucluse

The work conducted within the observatory is focused on improving the understanding and conceptual and numeric modeling of the hydrodynamic and hydrochemical functioning of various compartments of karst hydrosystems, within the context of global change. It is based on multi-disciplinary observations conducted at multiple scales. The downstream basin of this hydrosystem is one of the preferred experimental sites of the UMR 1114 EMMAH (AU-INRA) and the research community extends beyond karst hydrogeologists.

With an average interannual discharge of 20 m3/s, the Fontaine de Vaucluse is one of the largest karst springs in Europe. It is almost the sole outlet of an exceptional karst system, both in terms of the size of its drainage basin (1130 km2) and the thickness of the unsaturated (800 m on average) and saturated (>300 m) zones. The size of the system gives an approximation of the impact of lateral variability in ‘depositional environments’ of the carbonate facies, of processes of fracturing and karstification, and flow dynamics. In addition, the 3.7 km LSBB infrastructure tunnel offers unique access to flows in the infiltration zone. The Messinian ‘structuring’ of this karst is typical of the Mediterranean region. The conduit that conveys water to the spring has been studied as far as the elevation of -204 below mean sea level and is the origin of the term vauclusian system, which defines a karst system in which the drainage network has developed below the level of the outlet. Upstream of the spring, in the the Sorgues region, rivers are associated with important societal issues (flood warning, irrigation, biodiversity, and green tourism).

Long-term monitoring conducted by the observatory includes the following:

  • Monitoring of physical, hydrochemical, isotopic, and natural fluorescence parameters at the Fontaine de Vaucluse spring and at several tens of flow points in the unsaturated zone (the LSBB gallery
  • Hydrodynamic monitoring in karst cavities and boreholes (ZS and Unsat Zone)
  • Meteorologic monitoring (LSBB site)

Hydrometric monitoring of the spring is done by State agencies. Records include monthly averages since 1887, daily discharges since 1967, and hourly discharges since 1994.