OZCAR-RI SNO_KARST Mediterranean and coastal site of Port-Miou - France

The Mediterranean and coastal site of Port-Miou is a wide regional carbonate aquifer, with a catchment area around 400 km², in south of France (Provence, France). It extends mainly over natural land, in the vicinity of one of the main city of France (Marseille), facing recent urban expansion and future groundwater resources management issues. Top of the recharge area culminates at 1100 m asl, and the main outlets are submarine springs. Karst features are observed in surface (polje, intermittent rivers, sinkholes, karren, caves) and underground. Many karst networks have been explored in the unsaturated zone of the aquifer, but also in the saturated zone below the sea level. Karst features and conduits drive the groundwater flows to the main outlets. The Port-Miou submarine springs outflow from huge flooded karst conduits, explored by cave diving over several kilometers inland, and to -235 m deep. Groundwater is brackish, polluted by seawater intrusion. The Port-Miou observation site includes flow rate, salinity and temperature monitoring at the main brackish spring, in an in-situ underground laboratory located 500 m inland from the seashore, directly in the main karst conduit. Rainfall is also recording in the catchment area, and rain water samples are collected for water isotopes observation.