FORKARST is an hydrogeological observatory coordinated by Avignon University (UMR 1114 EMMAH) as part of the Network of National Karst Sites (SNO KARST). It gathers two experimental sites at interlinked scales : the fontaine de Vaucluse karst hydrosystem (basin scale) and the LSBB (Low-noise underground laboratory – local scale to mesoscale).
Fontaine de Vaucluse is the almost 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. With an average interannual discharge of 20 m3/s, it is one of the largest karst springs in Europe. The Messinian structuring of this karst is typical of the Mediterranean region. 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.
The LSBB is located at the southern edge of the Fontaine de Vaucluse karst hydrosystem. The 3.7 km sub-horizontal LSBB tunnel offers unique access to the infiltration zone, under a rock cover 30 up to 519 m thick. At the surface, two experimental boreholes platforms allow characterization of the link between geological, hydrogeological, hydrochemical and geophysical parameters in the infiltration zone.
The LSBB is an high-instrumented site of INSU. Within this pluridisciplinary research platform, the hydrogeological, seismic, magnetic and radiative properties monitored by different teams are commonly interpreted in order to identify correlations and lead to a multi-physical characterization of the karst hydrosystem.