From historical data to modern geomorphological approaches in anthropogenic areas: multitemporal landscape evolution and geomorphological assessment of Milan, Italy.

This thesis explores the complex interaction between geomorphological evolution, hydrological transformations, and urban development in the city of Milan. By combining historical data, spatial analysis, and multi-temporal cartographic sources, the work aims to deepen the understanding of landscape changes in an urbanized environment and their implications for hydromorphological processes. The research in this thesis examines the urban landscape evolution of Milan city through an integrated approach that combines historical data analysis, geomorphological investigation, and flood-related spatial assessments, with a focus on the Seveso River and its mitigation strategies, and, following this analysis, proposes measures to reduce flood risk and mitigate the impacts of extreme rainfall. The thesis is structured into three main phases that build upon each other to provide understanding of how long-term human activity and physical transformations shape the city and flood risk in the city: i) a bibliographic review focusing on both the state of the art in urban geomorphology and the specific geomorphological characteristics of the city of Milan; ii) an assessment of the fluvio-dynamic system flowing through the city; iii) an analysis of landscape evolution from an urban geomorphological and hydrological perspective, assessing flood dynamics and mitigation strategies through multitemporal data, fieldwork, and mapping in accordance with ISPRA guidelines. The first phase focuses on literature review and proposing a methodological approach. The review also emphasized the growing importance of integrating natural elements into urban studies, especially in areas where environmental pressures and human activity intersect. Based on this, a two-part methodological framework was developed and applied to northern Milan, an area characterized by intense landscape transformation and high flood susceptibility. In the second phase, the research focuses on the hydrological assessment, especially focusing on the Seveso River, a heavily modified watercourse in northern Milan subject to repeated flooding episodes. The study combined spatial and temporal analyses including land use, river morphology, physical characteristics, and hydrological records with field surveys and historical map interpretation to examine river evolution and surrounding landscape changes. Channelization, burial, and surface sealing were identified as key processes increasing runoff and flood susceptibility. Hydrological analyses confirmed altered flow regimes and greater flood frequency, while population data quantified residents currently exposed to flood risk along the river. In the third and final step, the analysis was extended to the entire city of Milan. Historical cartographic materials from 1886, 1956, and 2020 were collected, digitized, and compared to assess urban growth and its impact on geomorphological feature. A 5 m digital elevation model (DEM) was used to support terrain analysis and verify the extent of natural and anthropogenic landforms. This analysis allowed the identification of changes in elevation, excavation activities, and other human-induced modifications. In particular, the analysis of the Seveso River focused on its current geomorphological structures and flood mitigation strategies, emphasizing the underlying factors that limit the effectiveness of the applied interventions and contribute to the continued exposure of certain urban areas to flooding. The analysis of the Seveso within Milan provides a scientific basis for advancing adaptive flood mitigation through the integration of geomorphological understanding and urban interventions. The findings demonstrate that implementing underground stormwater storage systems could enhance the capacity of city to regulate runoff, reduce hydrological stress on existing drainage networks, and support long-term climate resilience.