Fontaine de Vaucluse

The Fontaine de Vaucluse is one of the most famous and best explored karst springs in the world, located in Provence, about 30 kilometers east of the city of Avignon. The deep siphonal karst conduits, the huge discharges variation and the high minimal discharge values during low flows attracted researchers from all over the world. Blavoux et al. (1992) defined a catchment area of about 1,100 km² (today up to 1,160 km²). The Lower Cretaceous limestones of Urgonian facies (Barremian-Aptian age) are 1,500 meters thick and highly karstified. The thickness of the unsaturated zone can exceed 800 meters; four chasms on the plateau are more than 500 meters deep (Gaubert and Le Falher, 1990), and one shaft reaches the saturated zone 30 kilometers upstream the spring.
The spring comprises a siphonal pool with an upper outlet which flows only during high water periods and a downstream outlet where groundwater continuously discharges through thick debris zone with huge fallen blocks, giving rise to the Sorgue River, one of the Rhône’s tributaries. Over one hydrological year, the mean water table level fluctuations at the outlet are of about 25 meters (Blavoux et al., 1992; Cognard-Plancq et al., 2006; Bonacci, 2007).