Assessing and mapping of land subsidence risk at different scales in major urban areas in Italy 

High to very high susceptibility and hazard levels of land subsidence have been identified in several Italian regions: Emilia-Romagna and Veneto regions, where loss of land elevation up to 7 cm/year in the Po River Plain impacts 30% of the Italian population since the 1950s; Puglia, e.g. at Tavoliere Plain, with land subsidence up to 2 cm/year; the Florence-Prato-Pistoia Plain in Tuscany and the Volturno Plain in Campania, with more 2 cm/year; the Gioia Tauro Plain in Calabria with more than 1 cm/year. Assessing the contribution of urbanization and the growth in urban population to this process is still a challenging task. The SubRISK+ project is aimed to provide new Earth observation-derived products and tools to improve the comprehension of current and future land subsidence in major urbanized areas of Italy. The project is funded by the European Union – Next Generation EU, in the framework of the Research Projects of Significant National Interest (PRIN) - National Recovery and Resilience Plan (PNRR) call 2022, and it is led by the National Research Council of Italy in Rome with the collaboration of the University School for Advanced Studies of Pavia and the University of Padua. In particular, the risk associated to land subsidence will be investigated for the 15 metropolitan cities of Italy and the Emilia Romagna region by exploiting Copernicus’ European Ground Motion Service (EGMS) data. Satellite-based Interferometric Synthetic Aperture Radar (InSAR) observations will be employed to map the current land subsidence and assess the potential induced damages to urban infrastructures. Then, a multidisciplinary approach incorporating geological, hydrogeological, geotechnical, land use data, and ground displacement observations will be implemented to disentangle the contribution of various processes and evaluate the associated triggers. The activities will be performed across national, regional, and local scales. The use of advanced groundwater flow and geomechanics model for a “hotspot city” case study will allow to quantify the effects of groundwater exploitation and estimate uncertainties in land subsidence. Market and non-market direct/indirect losses will be assessed at national, regional, and local scales via a newly developed socio-economic impact analysis, based on the exposure, vulnerability, and resilience of the investigated urbanized areas. Finally, future land subsidence risk scenarios will be estimated in the medium (2050) and long term (2100).