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Land subsidence in urban areas is a highly significant and globally widespread geological hazard. This type of ground deformation process commonly occurs in rapidly expanding cities due to the combined effects of structural loading from built infrastructures and excessive groundwater withdrawals due to the increasing water demand of growing populations and industries. In this study, we perform a detailed analysis of ongoing subsidence in Bologna (Italy), with respect to historical pumping trends and a 3D geological model of the subsurface. Since the 1960s, the city of Bologna has experienced severe subsidence attributed to the overexploitation of aquifers for civil water use. Ground deformation peaked in the 1970s, with documented maximum rates of approximately 100 mm/year, causing structural and infrastructural damages. Over the years, the subsidence process has been intensively monitored by local authorities, collecting extensive ground displacement measurements employing different and increasingly sophisticated techniques, including topographic levelling and satellite interferometry. Long-term data are essential for a comprehensive understanding of the subsidence process evolution and for calibrating numerical or statistical predictive models. Therefore, we developed a methodology to integrate ground-based and remotely sensed monitoring data and produce cumulative ground displacement time series and maps, capturing the long-term temporal evolution and spatial distribution of the subsidence process, respectively. The long-term deformation field reconstructed consistently aligns with the 3D geological model of the area, and the produced cumulative displacement curves consistently match the pluriannual trends observed in groundwater level and pumping monitoring time series. [ABSTRACT FROM AUTHOR]

Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) techniques are gaining momentum in the assessment and health monitoring of infrastructure assets. Amongst others, the Persistent Scatterers Interferometry (PSI) technique has proven to be viable for the long-term evaluation of ground scatterers. However, its effectiveness as a routine tool for certain critical application areas, such as the assessment of millimetre-scale differential displacements in airport runways, is still debated. This research aims to demonstrate the viability of using medium-resolution Copernicus ESA Sentinel-1A (C-Band) SAR products and their contribution to improve current maintenance strategies in case of localised foundation settlements in airport runways. To this purpose, "Runway n.3" of the "Leonardo Da Vinci International Airport" in Fiumicino, Rome, Italy was investigated as an explanatory case study, in view of historical geotechnical settlements affecting the runway area. In this context, a geostatistical study is developed for the exploratory spatial data analysis and the interpolation of the Sentinel-1A SAR data. The geostatistical analysis provided ample information on the spatial continuity of the Sentinel 1 data in comparison with the high-resolution COSMO-SkyMed data and the ground-based topographic levelling data. Furthermore, a comparison between the PSI outcomes from the Sentinel-1A SAR data—interpolated through Ordinary Kriging—and the ground-truth topographic levelling data demonstrated the high accuracy of the Sentinel 1 data. This is proven by the high values of the correlation coefficient (r = 0.94), the multiple R-squared coefficient (R2 = 0.88) and the Slope value (0.96). The results of this study clearly support the effectiveness of using Sentinel-1A SAR data as a continuous and long-term routine monitoring tool for millimetre-scale displacements in airport runways, paving the way for the development of more efficient and sustainable maintenance strategies for inclusion in next generation Airport Pavement Management Systems (APMSs). [ABSTRACT FROM AUTHOR]