A Messinian model explains the salt contamination of the Mediterranean Coastal Springs

Abstract

Mediterranean submarine karst springs could feed millions of persons in areas that suffer from scarcity of water but they are brackish which limits their use. The water comes from deep karst galleries which were explored by cave divers. There were many attempts to catch the water by building dams or bells to prevent sea intrusion in the cave, or to augment the water head for lowering the haline interface, according to the Ghyben–Herzberg relation. They failed as the water remained brackish upstream to the works. Recent studies show that salinity is acquired at a very important depth (> 200 m) by mixing of fresh water and sea water in deep zones where karst galleries were dug during the Messinian salinity crisis (5.9–5.3 Ma), when the sea level dropped down to 1500–2500 m. The validation of this Messinian model is a starting point for the use of this water resource by drilling deep wells, upstream of the galleries junction or by blocking the intrusion in the Messinian galleries.