The value and the need of nature-based solutions for resilient urban ecosystems: from citizen engagement to novel Nexus perspectives for fair and safe use and development of natural and urban resources Insights from the city of Rome (Italy) water resource and risk management programs

The three million inhabitants of the city of Rome are mostly unaware of the significant hydrological and meteorological risks affecting the urban ecosystems. Floods, droughts, landslides, sinkholes as well as urban and industrial pressures impacting the safety and sustainability of natural and human resources. The city, following a significant urban and demographic growth of the last 50 years, is still one of the largest agricultural metropolises in the world. Fair and safe access to water, food, energy and environmental resources is no longer a mere optimization challenge (i.e., given for granted), but a real (and actually pressing) urban and land development challenge. Decision makers are prompted to take important actions and design a medium to long term vision to guarantee (preserve) the abundance of resources that gave birth to one of the wealthiest early civilizations in the world. Competing and often conflicting economic sectors uncertainties, driven by social and climate change, and lack of financial resources to cover all needs and mitigate all natural and human-driven hazard characterize a multi-risk multi-actor multi-sector grand challenge for the City of Rome. This challenging framework is not merely a technical challenge, but several diverse factors increase the complexity from multiple perspectives (governance and policy, human behaviour, social and cultural etc.). The European Green Deal is providing an integrated framework where long time existing policies and technical regulations on safe and sustainable natural and urban planning (Water Framework, Biodiversity, Circular economy, Blue Growth Directives, etc.) are joining efforts under one umbrella embracing green and blue principles. Nature based solutions offer multiple advantages, but the transition from grey infrastructure and engineering towards green and blue growths is facing several technical and cultural challenges. This contribution presents experiences, issues, insights derived from recent and ongoing scientific and applied research projects and urban development projects for the city of Rome with specific regard to water resource and risk management programs and interlinked landscape planning actions. Among the interlinkages and multi-disciplinary feedbacks, the water-human, water-food and the extended water-food-ecosystem nexus dynamics are investigated and presented at the conceptual level. Specific interest and focus of this work are the value and the need of preserving and further developing green, blue spaces as well the significant natural and cultural heritage that characterize the city of Rome. Further foci are linked to the cultural, social and economic value of also preserving the agricultural footprint of the extended metropolitan region of Rome (and Lazio region). The presented case study shows the importance of enlarging and interfacing the perspectives while implemented the European Green Deal at the urban level testing both bottom-up and top-down approaches, investigating the optimal governance dynamics that shall be implemented for successful embracing of water and blue actions. A wide range of components, methods, procedures that govern safe and sustainable urban planning are presented from citizen engagement to urban and engineering design for identifying and fostering the most suitable actions that would promote resilience and safety of complex urban setting, like the selected city of Rome case study.