Scientists may have found freshwater locked in Maltese seafloor from 20,000 years ago

Strong indications of freshened groundwater offshore in south-east of Malta between Valletta-Marsascala coastline

An international team of scientists has reported strong indications of freshened groundwater offshore the coastline between Valletta and Marsascala, in the south-east of Malta.

The discovery, a product of the oceanographic MARCAN expedition carried out in 2018, is published in the international journal Geophysical Research Letters and included scientists from Malta, Germany, Spain and Italy.

Seismic reflection profiles were used to create a geological model of the seafloor offshore the Maltese islands, as well as electromagnetic surveying to identify anomalies in electromagnetic resistivity beneath the seafloor.

These observations indicate that freshened groundwater occurs as an isolated body hosted in Globigerina limestone located 3km away from the coast.

A second offshore groundwater body may exist within 1km of the Maltese coastline, the bulk of which was deposited 20,000 years ago when sea-level was lower than today.

“There are a number of important implications associated with this discovery. Offshore freshened groundwater may constitute a new, unconventional source of potable water that should be considered in future national water management strategies for the Maltese islands,” the scientists said.

“The occurrence of freshened groundwater offshore a dry, limestone coastline such as the Maltese one bodes well for similar settings in the Mediterranean region that are suffering from water scarcity.

“On the other hand, the exploitation of the Maltese offshore groundwater system is likely unsustainable, because it is not being actively recharged, and pumping rates are likely to be low.”