Historical cartography as an analytical tool for sinkhole investigation: case studies from the Lazio region (Central Italy)

Stefania Nisio¹ & Sergio Madonna²
sup>1ISPRA – Dipartimento per il Servizio Geologico d'Italia , Via Vitaliano Brancati 48, 00144 Roma.
sup>2Università degli Studi della Tuscia - Via San Camillo de Lellis, 01100 VITERBO (VT).
Corresponding author e-mail: sermad@unitus.it

The integrated study of sinkholes in Italy highlights the foundational role of historical cartography, archaeological data, and archival sources in identifying areas of potential hazard. Historical maps, prints, and aerial photographs, when analysed through diachronic comparison, enable the detection of sudden morphological changes (e.g., sub-circular topographic depressions, ponds, and hydrographic modifications) that may signal the formation of sinkholes. This approach is particularly effective in contexts where modern topography no longer preserves clear evidence of subsidence due to urbanisation or land reclamation. Historical cartography, aerial imagery, and cartographic inventories thus provide critical constraints on the spatial and temporal evolution of sinkholes, including their size, frequency, and development through time. Over the last few decades, the Italian Geological Survey (ISPRA), the official body of the Italian Institute for Environmental Protection and Research, has systematically investigated collapse phenomena (sinkholes). These sources have been collected, georeferenced, and integrated into GIS platforms to support spatial analyses. Within this framework, historical and archaeological evidence has proven essential not only for identifying potential underground cavities but also for reconstructing palaeohydrographic systems that may still influence present-day subsurface water dynamics and sinkhole susceptibility. Furthermore, the analysis of historical cartography reveals that numerous small, sub-circular lakes were present across the territory in the past, many of which have since disappeared. Notably, several of these features were located within areas currently classified as sinkhole-prone, where recent events have been documented. This correspondence suggests that a significant proportion of these former lakes may be attributable to past sinkhole activity. In particular, within alluvial environments characterized by cohesive sedimentary cover, such features are plausibly associated with piping sinkholes.

sinkhole, historical cartography, hazard assessment, historical aerial photographs, GIS-based analysis.