Integrated Geomatic Solutions for the Digital Twin of Florence: Protecting the Arno River and its Historic Urban Landscape from Climate Risks

Abstract. The interplay between urban environments and waterways is a critical aspect of sustainable city planning, particularly in historic settings vulnerable to climate change. This study presents the Digital City & River Twin (DiC&RT) framework, focusing on the historic urban fabric of Florence and its interaction with the Arno River. Unlike conventional Urban Digital Twins (UDTs), which often address isolated domains, DiC&RT intends to analyse the complex relationship between the river and the historic city by means of integrated geomatic techniques. The project addresses flood risks, structural stability, and environmental dynamics by creating a comprehensive multi-layered model. DiC&RT employs diverse data acquisition techniques, including static and kinematic LiDAR scanning, unmanned aerial and surface vehicles for photogrammetry and bathymetry, and ground-penetrating radar for subsurface analysis. A geodetic control network ensures high-precision data integration, supporting long-term monitoring. The study assesses the effectiveness of these methods in capturing the geometric and environmental characteristics of the riverbanks, bridges, and urban infrastructure. The results demonstrate the necessity of combining multiple surveying technologies to obtain a holistic representation of the study area. By integrating spatial and predictive modeling, DiC&RT enables real-time risk assessment and scenario simulations for climate change adaptation. This framework offers a scalable solution for heritage conservation, risk analysis, and adaptive urban management, potentially serving as a model for other historic cities facing similar challenges.