Spatial Distribution of Field Physico-Chemical Parameters in the Vulcano Island (Italy) Coastal Aquifer: Volcanological and Hydrogeological Implications

Vulcano, the southernmost of the Aeolian island arc (Italy), is characterized by a
shallow coastal aquifer resulting from the mixing of seawater, meteoric recharge and
volcanogenic fluids. The aquifer has been intensively studied during the last decades, but a
comprehensive hydrogeological model has never been developed due to the lack of direct
information about the litho-stratigraphic columns of the wells and the depth of water
bearing levels. We present and discuss here the time and spatial analysis of water table
elevation, temperature and electric conductivity data, acquired during the last 20 years in
33 wells located at Vulcano Island, with the aim of developing a groundwater circulation
scheme able to fit the field observations. We retrieved a circulation scheme characterized
by an intricate geometry of flow paths driven by horizontal and vertical permeability
variations, accounting for the strong variability of geochemical data evidenced in this area
by the related scientific literature. Extending these results to a general context, particular
care must be taken in approaching the study of aquifers in volcanic islands, because a
strong, small spatial scale variability of the hydrogeochemical parameters is expected, and
a reliable knowledge of the local conditions is required for developing successful
groundwater circulation schemes.

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