The influence of anthropogenic topographic changes on geomorphological processes in the city of Rome (Italy). A case study of the Malagrotta area

Rome's urban landscape presents a clear urban–rural gradient, with diminishing human influence from the historic city center to the surrounding outskirts and peri-urban areas. Millennial urban growth resulted in drastic changes of natural landscapes, making it an invaluable case study for examining human impact on natural geomorphological processes. Despite the importance of understanding these interactions for managing geomorphological risks, the role of human activity along the urban–rural gradient remains poorly understood. This study explores human-induced geomorphic changes in Rome's Malagrotta quarrying and dumping area established in the 1980s, focusing on erosion, transport and sedimentation processes that challenge sustainable land use. Using the slope–area relationship, applied on digital elevation models across different time periods (1894, 2002 and 2023), we identify local process domains to better understand how human activity influenced landscape dynamics over time. Results reveal that extensive quarrying and excavation activities between 1894 and 2002 removed nearly 3 × 107 m3 of material, while the period from 2002 to 2023 saw the removal of 7 × 106 m3. Dumping and ancient quarry and valley filling added approximately 2.6 × 107 m3 of material, compared with 1.4 × 107 m3 in the later period. Regions with convergent morphological deviations are generally linked to excavation and quarrying activities while divergent patterns align with filled depressions. High slopes from quarry escarpments are prone to erosion and landslides. While stream power and topographic wetness index shifts suggested increased flood risks and altered hydrological patterns. These findings underscore the need for geomorphologically informed urban planning to mitigate erosion, landslides and flood hazards in urbanizing landscapes globally.