Insights on the paleohydrography and hydrogeology of urban areas in volcanic settings: the case study of Catania, Italy

Abstract

This study provides insights on modification of the drainage network within the urban area of Catania (southern Italy) by the recurrent volcanic eruptions of Mount Etna that occurred throughout the Holocene. The oldest lava flows identified within the urban area were emplaced around 5000 BC, culminating in the most recent lava flow that reached the city in 1669. By integrating historical documentation, field observations, and geotechnical borehole data, the original morphological configuration of the area was reconstructed to delineate the pre-eruptive surface drainage system prior to burial by lava flows. The geometry and depth of the paleovalleys were further constrained through estimation of the thickness of the lava flows filling these preexisting depressions. The results highlight a substantial reorganization of the local geomorphology, wherein former valleys were transformed into topographic highs, markedly altering drainage pathways and infiltration dynamics. This long-term landscape evolution continues to exert a persistent control on the spatial distribution and movement of groundwater. In particular, the principal subsurface flow directions align with the axes of the ancient surface drainage network, while the thickest lava sequences constitute the most productive groundwater reservoirs owing to their enhanced secondary permeability.