Résumé
The Causse d'Aumelas karst aquifer (about 200 km (super 2) ) is located at 20 km westward Montpellier, France. During low flow periods, part of the intermittent river, the Coulazou is sinking when it traverses the karstic aquifer. More than 15 karstic events, which can function alternately as sink holes or springs, have been observed in this hydrosystem. In order to understand the interactions between surface waters and groundwater, hydrodynamical and hydrochemical monitoring has been carried out on springs, boreholes, swallow holes, and on the Coulazou river. Water samplings are now completed twice a month at each point since September 2004. This "multiparameters" approach will underline the behaviour of the hydrosystem, especially the phenomena of flow inversions. The understanding of these specific links between surface and subterranean waters are fundamental to estimate the vulnerability of the aquifer and to protect water resources in this Mediterranean context.