Evaluation of over-exploitation effects for the Salento coastal karstic aquifer through the interpretation of thermo-conductivity logs in observation wells

The Salento Peninsula represents a notable example of coastal karstic aquifer where the quality of groundwater is affected by salinisation due to seawater intrusion. Main cause of groundwater salinisation is the uncontrolled withdrawal of a global water volume that overcomes the exploitable fraction of the annual recharge. Previous studies on the salinisation of the Salento aquifer demonstrated that the monitoring of the phenomenon can be effective only performing thermo-resistivity logs which allow the direct recognition of the salinity and temperature distribution in depth. The possibility to outline the equilibrium conditions between freshwater and underground saltwater derived mainly from the availability of observation-wells and related thermo-resistivity logs. Consequently, it was suggested that any future monitoring net in the region should be based on a convenient number of “observation-wells” (i.e. wells reaching underground salt waters), distributed in the territory according to the characteristics of the various zones of the aquifer. This monitoring net has been finally realised. In view of its operation start, a few criteria, concerning the way to perform data collection and their interpretation, are proposed. Moreover, an updated approach in the elaboration of thermo-resistivity logs leads to the definition of a few new parameters that prove suitable to quantify and follow the evolution of freshwater-saltwater equilibrium.