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This work aims to describe, classify, and analyze the occurrence of selected natural multi-hazards, specifically pluvial floods and sinkholes, affecting a district in the urban area of Rome, Italy. The procedure is based on a robust geological, geomorphological, and hydrogeological analysis performed using data collected and archived for the scope. The susceptibility is calculated based on geo-hydrological and geomorphological factors, as well as the occurrence of flooding and sinkholes. The areas prone to each single hazard were combined and put into the context of multi-hazard assessment by overlaying the susceptibility with buildings and population data. The resulting map shows that 50% of buildings (6215 inhabitants) are in an area of multi-hazard susceptibility; among these, 25% are in the highest multi-hazard classes (4 and 5). These areas are named "multi-hazard hotspots" because they are affected by many hazards with associated higher impacts. This study demonstrates that a comprehensive approach that combines the examination of geology, hydrogeology, modifications to historical morphology, and the occurrence of geological disasters is effective for mapping geohazards in urban areas and identifying locations with multiple hazards. A multi-hazard hotspot map can be used as a tool for planning actions aimed at reducing the vulnerability and exposure level of the urban population. [ABSTRACT FROM AUTHOR]

The role played by the anthropogenic deposits with poor geotechnical characteristics to induce seismic amplification and its influence on hydrogeological conditions, due to its permeability characteristics, has been demonstrated by numerous studies conducted in urban environments. The historical center of Rome (Italy) is characterized by the presence of high thickness of anthropogenic deposits, a stratigraphic unit that accumulated during the centuries of urban development. The modeled reconstruction of this unit could provide a tool for the elaboration of preliminary maps used for urban planning by public institutions. In this work, the reconstruction of the basal surface of the anthropogenic deposits was carried out using lithostratigraphical and geotechnical data recorded in 1355 boreholes drilled within the historical center of Rome. Deterministic and geostatistical estimators have been then used to predict the values at non-sampled locations to construct different maps of the basal surface. Grid statistics allowed the comparison of the obtained maps to select the best spatial predictor. Mono and multivariate geostatistical intepolators [ordinary kriging, kriging with external drift (KED) and cokriging] have been selected and discussed, and KED was the best interpolator for the used dataset. The obtained surface was then used to calculate a thickness map by subtracting it to the Digital Terrain Model. Furthermore, results of some mechanical characteristics of the anthropogenic deposits are presented and discussed in the light of the reconstructed geometry. The knowledge of both geometry (i.e., basal surface and thickness) and mechanical characteristics of these deposits could provide useful information for the evaluation of geological hazards in urban areas. [ABSTRACT FROM AUTHOR]

This study presents the results of a research project financed by the Lazio Regional Government. The research focused on defining an integrated model of recent alluvial deposits in the Tiber River. To achieve this objective, geological boreholes were made to monitor the aquifer and in situ and laboratory tests were carried out. The data obtained were used to detail stratigraphic aspects and improve the comprehension of water circulation beneath the recent alluvial deposits of the Tiber River in the urban area of Rome, between the Ponte Milvio bridge and the Tiber Island. The stratigraphic intervals recognised in the boreholes were parameterised based on their litho-technical characteristics. The new data acquired, and integrated with existing data in the database of Institute of Environmental Geology and Geoengineering of the Italian National Research Council, made it possible to produce a three-dimensional model of the lithologies in the study area. The model of the subsoil, simplified for applied reasons, was described in hydrostratigraphic terms: three different lithotypes were subjected to piezometric levels monitoring. Finally, the research generated a numerical hydrological model in a steady state. In general, this study demonstrates how a numerical hydrogeological model calibrated by piezometric monitoring data can support the construction of a geological model, discarding or confirming certain hypotheses and suggesting other means of reconstructing sedimentary bodies. [ABSTRACT FROM AUTHOR]