Urban Hydrological Adaptation Through GBI and NBS: A Comparative Study of European Case Studies.

Green and Blue Infrastructure (GBI) and Nature-Based Solutions (NBS) are becoming increasingly important for sustainable water management and climate change adaptation, especially in urban areas facing greater hydrological pressures. This study uses a literature-based comparative analysis, based on a critical review of scientific publications, technical reports, and design documents. The analysis focuses on two European case studies: the proposed GBI/NBS project in Grundarfjörður, Iceland, and the completed intervention at the Scalo intermodale di Milano–Segrate.
The analysis shows that the Grundarfjörður project mainly tackles heavy rainfall and rapid surface runoff by adopting sustainable urban drainage systems combined with microclimatic adaptation strategies. This takes place within a setting of high climatic variability and intricate geopedological conditions. Conversely, the Milan–Segrate case, evaluated solely through published project documents and monitoring records, concentrates on reducing hydraulic risk, environmental regeneration of a key infrastructural zone, and the multifunctional role of open spaces as vital links between hydraulic systems, landscape, and urban areas.
The comparison based on the documentary highlights notable differences in bioclimatic conditions, design approaches, and the importance of environmental monitoring for the long-term assessment of GBI/NBS performance. These results underline the need for a unified methodological framework that combines urban hydrology, ecology, and spatial planning to enhance solution transferability and strengthen the reliability of long-term effectiveness evaluations.