Assessing quantity and quality of groundwater in small islands and make it immediately usable in a sustainable way by the population during droughts or in case of great tourist pressure is now possible thanks to a study conducted by ENEA in Favignana,

in the Egadi archipelago in Sicily. Through hydrogeological, precipitation and temperature rates measurements and chemical analyses of groundwater, the island's water reserves were assessed and the ones with better quality or, on the contrary, more exposed to the risk of salinisation by seawater intrusion, identified.

Electrical conductivity classes of the water taken from the wells analyzed in Favignana

"The capability of determining the amount of water that infiltrates the subsoil by feeding the aquifers is an important added value. The method we used in Favignana can be replicated in other contexts and in the small islands the impact of these insights can be significant both from a social and economic point of view ", continues Cappucci.

"It’s a hydrogeological balance which, just like an economic balance sheet, allows to estimate cash inflows, that is the infiltrations, and outflows, that is water consumption and loss of the island of Favignana, which was chosen for its climatic and geomorphological characteristics and the great tourist pressure in summer, " ENEA researcher Sergio Cappucci who coordinated the study, explained.

Fresh water, which does not evaporate as a result of rainfall and infiltrates underground, floats above salt water because it is less dense and, consequently, pushes more in depth the less suitable waters to be used for civil or irrigation purposes.

The communities of the islands have always known how to manage the island’s groundwater resource, developing techniques to collect and preserve rainwater, but growing tourist pressure has made it necessary to find an external supply over time, resorting mainly to tankers, given the costs and technical difficulties of creating desalination plants or underwater pipelines to bring fresh water from the mainland.