Geoscientists have identified a vast underground freshwater reservoir hidden beneath Sicily’s rugged mountains. The discovery suggests a water volume comparable to roughly one third of Spain’s total reservoir capacity, which could reshape regional water security and resilience for Sicily and neighboring areas.
The finding is reported in a recent study published in Contact Earth and Environment. Researchers traced groundwater around the Gela formation, located under the Hyblean Mountains, by reusing data originally created for oil exploration. This approach shows how legacy geoscience datasets can reveal valuable freshwater resources that lie beyond the reach of traditional drilling programs.
Water supply reliability has long been a priority for Sicilian authorities due to the island’s high population density and Mediterranean climate. To address rising demand, scientists conducted an in-depth assessment of untapped groundwater resources to strengthen local planning and resilience against climate variability.
Precise location markers accompany the findings, underlining the practical importance of accurate subsurface mapping in water security planning.
Using data from oil-field surveys and maps, researchers reconstructed the subsurface to identify what appears to be a previously unknown aquifer beneath the Hyblaean Mountains. The evidence points to a substantial freshwater system that warrants thorough evaluation and careful development planning.
Substantial freshwater reserves beneath the Hyblaean Mountains
Estimated depths for the aquifer range from 800 to 2,100 meters. Three‑dimensional reservoir models corroborate the initial assessments, indicating a water volume around 17.5 cubic kilometers. At this scale, the aquifer could influence regional water resources, storage strategies, and drought preparedness for nearby towns, agriculture, and industrial areas.
To put this volume into perspective, all the reservoirs across Spain store roughly 54 cubic kilometers. While regional differences matter, the Sicilian aquifer represents a meaningful opportunity to bolster local supply and inform long‑term water resource planning in southern Europe.
Deposit formation scenarios accompany the study, illustrating how the aquifer might have become trapped within the fold of the mountains. Researchers propose that the water accumulated over millions of years during the Messinian Salinity Crisis, a period when the Strait of Gibraltar narrowed and the Mediterranean’s sea level fell, exposing large seabed areas to rainfall.
A key mechanism proposed is rainfall percolation into carbonate rock layers acting as natural sponges, gradually loading the crust with groundwater. When sea levels later rose, the resulting seawater pressure could have helped seal the aquifer beneath the ascending mountain belt, preserving this substantial freshwater body for geological timescales.
Another possibility involves a channel formed by ancient rainfall linked to the Malta Escarpment, a feature looping around eastern Sicily and potentially guiding meteoric waters toward the Hyblaean region. The study presents this idea as a potential driver of the aquifer’s location and longevity, inviting further multidisciplinary research to test and refine the model.
Reference work: DOI: 10.1038/s43247-023-01077-w
[Citation: Contact Earth and Environment]