Résumé
The Fontestorbes karst Sp. is located near Belesta, southern France (Ariège). It is known as one of the largest intermittent springs in the World and became a classified touristic site in 1921. Numerous studies have been done on this karst spring, especially in the 70's by the French hydrogeologist A. Mangin who defined a physical model able to reproduce this intermittent flow behavior. Since 2014, the BRGM (French Geological Survey) leads a project in partnership with Région Occitanie, Ariege and Aude Councils, and AERMC and AEAG Water Agencies, that aims at better understanding the karst groundwater resources on the Plateau de Sault. In that framework, a scientific cooperation with the Speleogical Comitee (CDS09) allowed to monitor simultaneously pressure, temperature and electrical conductivity times series at the spring and in a cave explored by CDS09. This cave, located 1200m upstream the spring ends with two sumps that show water-level fluctuations related to the intermittent flow at the spring. Besides, a simulation of the karst drainage network following the KARSYS approach, and based on the interpretation of a 3D geological model, supposes that this cave is located on the karst drainage conduit conveying water from the southern part of the catchment area to the spring. These new results will be presented and discussed to better understand the intermittent mechanism , the karst network organization upstream the Fontestorbes Sp. and the origin of water flowing at the spring.