European cities and regions have faced unprecedented climate change in recent decades. Increasingly frequent and intense heat waves, flash floods and the associated degradation of the urban environment are posing a critical challenge. infrastructure under enormous pressure. Traditional engineering solutions, known as „gray“ infrastructure, are reaching their capacity and technological limits.

1. Climate challenges and the limits of "gray" infrastructure

In this context, they come to the fore Nature-Based Solutions (NBS) as a key and strategic tool for strengthening the climate resilience of cities. NBS not only mitigate climate risks, but also bring significant synergistic effects in the form of supporting biodiversity, social inclusion and overall improvement of the quality of life of residents in urban environments. Despite their enormous potential, however, the systematic integration of NBS into spatial planning and decision-making processes at the European scale has so far encountered fragmentation and insufficient methodological guidance.

2. Life cycle of the NBS according to the NBSINFRA project

For the successful implementation of natural solutions, it is essential to abandon the concept of isolated interventions and move to a holistic approach based on the project life cycle. NBSINFRA project defines this approach through five interconnected and iterative phases:

1. Assessment: Deep understanding of the local context, analysis of risks, vulnerabilities, infrastructure needs and identification of opportunities where NBS can bring the highest added value.
2. Planning & Design: Co-design solutions with the involvement of all key stakeholders and the public using data, creativity and modern digital tools.
3. Implementation: The actual implementation and deployment of selected natural solutions directly in the field, which requires close coordination of technical, regulatory and organizational parameters.
4. Operation & Maintenance: Long-term governance, routine care, and adaptive management that guarantee the continued functionality of NBS ecosystem services.
5. Monitoring & Evaluation: Continuous monitoring of technical performance, environmental and social benefits, thus closing the learning and optimization cycle for future replications.

3. Practical examples: Five European City Labs

The practical application of this life cycle is demonstrated by five urban labs within the NBSINFRA project, each bringing unique experiences from different phases of implementation.

• Ruse (Bulgaria): This Danube city faces risks of flooding, earthquakes and subsidence. As part of the assessment phase, the city successfully integrated local GIS data with the program's satellite data. Copernicus (including Sentinel data focused on vegetation phenology and the European Ground Motion Service). Thanks to the verification using the "Check by Monitoring" methodology, topological errors in the cadastre were eliminated and reliable risk maps were created. A monitoring network was installed for early warning of floods ACWA, which provides real-time environmental data directly to the city's decision-making system.
• Fingal (Ireland) and Aveiro (Portugal): These labs demonstrated the power of co-design and participatory planning. Fingal used a combination of expert flood modelling with tools such as CartoSpot to collect citizen input, consolidating 28 projects into a single resilience strategy. Aveiro addressed flash floods on the Vilar stream (Ribeira de Vilar) in an environment with fragmented private land ownership. The city deployed a hybrid analog-digital approach (a combination of interviews, printed maps, and a platform Geodesignhub). An exceptional step was the involvement of children and youth using the CartoSpot game, drawing and modeling with Lego, which helped transform the perception of water from a threat to a source of urban identity and opportunity.
• Prague (Czech Republic): The Prague laboratory demonstrates the technical implementation and benefits of long-term monitoring at four specific locations. Research Center CTU UCEEB tested experimental green roofs, bioretention and hybrid systems. The research confirmed that substrates enriched with biochar (biochar) have about 15–20 % higher water retention capacity and show better thermal damping effect. High school Ceskobrodska presented biosolar roof combining extensive greenery with photovoltaic panels. Research has shown that although the close mounting of the panels (6 cm above the substrate) limited the access of precipitation under them, the substrate under the photovoltaics was more thermally stable in winter, which significantly extended the life of the waterproofing membrane. The FarmBot system with rhizoboxes was tested on the Dejvice campus, while in the Bubny-Zátory brownfield, monitoring data helps design the NBS for a future district for 25,000 residents.
• Cologne (Germany): Cologne has many years of experience with flood protection on the Rhine. However, during the monitoring and evaluation phase, it became clear that climate change was bringing new types of threats, such as heat waves, droughts and flash floods. The city has therefore switched to a so-called. „"multi-hazard" approach. Using open data and the Copernicus program, it mapped existing blue-green infrastructure and integrated it with critical infrastructure elements, creating a reliable foundation for future planners.

4. Key recommendations for cities and policymakers

The results of the NBSINFRA project clearly define priorities for the successful replication of nature-based solutions in other cities:

• Integration into strategic plans: NBS should not be understood as additional aesthetic elements, but as an integral part of strategic spatial planning, investment programs and climate change adaptation strategies.
• Participatory governance: It is necessary to build trust through systematic, timely and inclusive engagement of citizens, landowners and experts from the diagnostic phase onwards.
• Supporting digitalization and interoperability: Cities should invest in modern digital tools (e.g. CartoSpot, Geodesignhub, IDSS) and promote open standards. A key innovation of the project was the creation of a common programming interface (NBSAPI), which enables seamless data exchange between different planning tools, preventing data duplication and supporting evidence-based decision-making.
• Institutional capacity building: The implementation of the NBS requires overcoming sectoral barriers (so-called institutional forces) within local governments and connecting experts from the fields of environment, transport, finance and asset management.

5. NBS as a strategic investment for the future

Implementing nature-based solutions in European cities is no longer just a matter of environmental activism or aesthetic enhancement of public space. The experience of the NBSINFRA project convincingly demonstrates that it is a highly effective strategic investment in the long-term safety, health and economic stability of urban communities. Moving from reactive crisis management to proactive resilience planning – built on robust data, inclusive planning and connections to technical infrastructure – represents the only viable path to a sustainable future for European urban space. JRi&CO2AI