A team of geoscientists has revealed a vast underground freshwater reservoir hidden beneath the Sicilian mountains. The volume of this aquifer is estimated to be about one-third of the total storage capacity of Spain’s reservoirs, highlighting a potential game changer for regional water security.
In a study published in Contact Earth and Environment the researchers detail how they repurposed data originally gathered to survey oil fields. The team used this existing data to map groundwater around the Gela formation, which lies beneath Sicily’s rugged terrain and hills, uncovering a previously unrecognized aquifer in the Hyblaean Mountains.
Local officials in Sicily have faced ongoing concerns about water supply as the Mediterranean island’s population and demand continue to grow. This prompted a detailed examination of underground freshwater resources that could remain untapped for years to come.
The investigators analyzed maps and survey data that had once supported oil exploration. Through this reanalysis, they identified what appears to be a substantial aquifer beneath the Hyblaean range, an area long believed to be dry in groundwater terms.
Large amounts of fresh water
Documentation indicates the deposit lies at depths ranging from 800 to 2,100 meters. Advanced 3D modeling of the aquifer confirmed the presence of a substantial water body, estimated at roughly 17.5 cubic kilometers. This is a remarkable quantity of fresh water, especially when compared to the total reservoir capacity of Spain, which sits around 54 cubic kilometers.
The team set out to understand how such a considerable amount of fresh water could become trapped under a mountain range. They propose that during the Messinian salinity crisis, roughly 5.3 million to 5.9 million years ago, the Strait of Gibraltar narrowed, causing parts of the Mediterranean to dry and exposing seabed to rainfall. This rainfall likely seeped downward, accumulating in the subsurface as a freshwater lens.
As sea levels rose again, seawater pressure helped seal the water within the carbonate rocks, effectively creating a natural sponge-like reservoir. The researchers also point to a potential ancient conduit, the Malta Escarpment, a geologic feature encircling eastern Sicily, which may have guided the rainwater into the subterranean karst and fracture networks.
Reference work: DOI: 10.1038/s43247-023-01077-w
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Additional context from this study suggests that such underground water networks could be more widespread than previously thought, particularly in tectonically complex regions where carbonate rocks form extensive reservoirs. If confirmed by further field measurements and long-term monitoring, Sicily might serve as a natural case study for the strategic management of groundwater resources in island settings with growing populations and agricultural needs. The implications extend to neighboring Mediterranean regions, inviting a reexamination of existing groundwater maps and a reconsideration of how subterranean freshwater is valued in regional planning.
Data and insights from this work align with broader efforts to understand aquifer systems that lie beneath mountain belts and carbonate platforms. By leveraging existing geophysical datasets and oil-field exploration techniques, researchers can uncover hidden water resources without the immediate need for new drilling expeditions. This approach offers a cost-efficient route to identifying potential freshwater reserves while supporting sustainable water security in water-stressed regions. (Attribution: Contact Earth and Environment)