Improving Blue-Green Transversal Connectivity in Cities: A Case Study of Munich and the Isar River

• Enhancing the connectivity of urban blue-green infrastructure (BGI) was explored • Transversal Connectivity Index (TCI) identified connectable BGIs depending on road width. • 74 green urban areas of Munich can be transversally connected to the Isar River. • Stepping stones (green areas < 0.8 ha) are critical elements to enhance connectivity. • Commitment by citizens and policymakers is key to implementation. Urbanization and the associated transport infrastructure, particularly roads, reduce connectivity between vegetated areas (green) and surface water systems (blue), fragmenting blue-green landscapes and limiting ecosystem functions and services. Enhancing blue-green infrastructure (BGI) connectivity is therefore essential for strengthening urban resilience to climate change impacts. Focusing on the city of Munich in Bavaria, Germany, and its Isar River, this study explores strategies to strengthen the transversal connection of the river to surrounding urban green spaces, aiming to establish a more integrated and expansive blue-green network, supported by different landscape planning strategies. This study uses the Transversal Connectivity Index (TCI) as a methodological approach to improve BGI connectivity in the transversal (extended lateral) dimension. Using open-source geospatial data (e.g., Urban Atlas, Tree Cover Density, Street Trees), we generate connectivity scenarios that highlight potential core areas for connectivity. The results reveal that up to 74 existing green urban areas are potentially connectable to BGI adjacent to the Isar River. Of these, 26 are small patches under 0.8 ha, which can perform as stepping stones and play a crucial role in facilitating connectivity. The methodological approach used demonstrates the possibilities of exploring BGI expansions and transversal connectivity for positively influencing ecosystem services in urban settings, such as biodiversity conservation, climate regulation and improved human well-being. Its application to other metropolitan areas may provide a basis for supporting urban BGI planning and management for sustaining and improving ecosystem services and benefits to human societies.