Coastal Karst Groundwater in the Mediterranean: A Resource to Be Preferably Exploited Onshore, Not from Karst Submarine Springs

摘要

Coastal karst aquifers are common in the Mediterranean basin. With their significant potential storage capacity, they are an attractive groundwater resource in areas where the water demand is the most important. They discharge either at the coastal zone or directly into the sea at karst submarine springs (KSMS). Decision makers take an interest in this unconventional groundwater resource and are convinced by companies and research consultancies that KSMS’s should be exploited because they would discharge huge amount of fresh water. Being now well documented, the occurrence of KSMS’s along the Mediterranean coast is discussed in the light of recent geological history favourable to the development of karst. Conduit flow conditions are common, inherited from an intense phase of karstification during the Messinian Crisis of Salinity at the end of Miocene, when the sea level was 1500 to 2500 m below present sea level. From investigations carried out along the coasts of France and the Levant, compared with studies done along other Mediterranean coastlines, it appears that capturing groundwater discharged at KSMS raises different problems which make the operation dicey and expansive.