Water management (SDG 6)

The "Active Recreational Green Area Development at Horváth-tető" in Miskolc is a project aimed at revitalizing a central yet underutilized urban space, commissioned by the Municipality of Miskolc in 2017. A distinctive feature of Miskolc is the Avas hill, located in the city center, which beautifully blends nature with urban elements. Despite its potential, the area had been neglected, particularly following the decline of vineyard culture and the reduced use of old wine cellars. To address this, a comprehensive development plan was initiated to rejuvenate the Avas region, with Horváth-tető at its core.
The project aimed to transform the area into an outdoor recreational hub for all age groups. The hill's historic terraces, once popular promenades, were repurposed into distinct, multifunctional spaces. Sports enthusiasts can enjoy facilities such as street workout stations, an outdoor gym, a skate park, a climbing wall, and parkour elements. For those looking to relax, picnic areas, sunbathing spots, and a retro-style terrace are available. The entire development prioritizes accessibility, providing inclusive options for visitors with mobility challenges.
The park also features significant landscaping, including the planting of trees, shrubs, perennials, ornamental grasses, and ferns, enhancing its overall appeal. Infrastructure improvements were made, including the restoration of stairs, paths, retaining walls, and the rainwater drainage system. A special shallow basin was designed to collect rainwater and support plant roots while also serving as a playful area for dogs within the dog park.
Since its opening in 2022, the park has become a popular destination, offering a tranquil escape in a beautiful setting. It provides a wide range of recreational opportunities for people of all ages, making it a valuable addition to Miskolc’s urban landscape and connecting the historical Avas hill with modern city life.(Ref.1,2)

The green belt regeneration project along the Byzantine Walls of Thessaloniki aims to revitalize the neglected green spaces surrounding these historic fortifications, which span 4 kilometers and are recognized as a UNESCO World Heritage site for their remarkable Byzantine architecture. The walls are located in Thessaloniki’s densely populated Upper Town, a factor that contributed to their environmental degradation. As such, the project focuses on restoring the degraded space surrounding the walls, improving the urban microclimate, and strengthening urban resilience while maintaining the area’s traditional character. By integrating heritage conservation with sustainable green infrastructure, the initiative seeks to provide both environmental and social benefits to the local community. Proposed by the Municipality of Thessaloniki and approved by the Greek government as part of a program that focuses on Central Macedonia, the project envisions a revitalized green zone along the walls, with vegetation and different types of trees being planted. However, some local families have expressed concerns, as the project involved the demolition of certain homes in the officially designated green belt area. (Refs. 1, 2, 3, 4, 14).

‘Grün macht Schule’ has been informing, advising, and supporting schools and school initiatives in Berlin since 1983 in the planning and realization of schoolyard projects. The program focuses on improving school playgrounds by creating child-friendly, natural habitats and ecological learning spaces, making schoolyards better equipped to address climate change. In 2012, the program expanded with the launch of the ‘Grün macht Schule - KinderGARTEN’ funding initiative, which extended support to kindergartens.
Over the past four decades, with the program’s assistance, Berlin has seen the transformation of large, unstructured schoolyards into smaller, creative playgrounds. These spaces now feature imaginative and artistic objects alongside facilities for play, exercise, and communication. Additionally, many school gardens and biotopes have been established or restored, turning school grounds into vibrant ecological and educational environments .
The projects are largely driven by schools’ self-initiatives, with ‘Grün macht Schule’ offering support throughout. This grassroots approach fosters pride and a sense of ownership among school communities, strengthening their identification with the results. The collaborative effort also enriches educational practices, promoting inclusion, integration, and democratic participation. Such initiatives offer a hands-on experience with sustainable climate protection projects, making these efforts tangible and impactful in everyday school life.
In addition to its project-based support, ‘Grün macht Schule’ provides training for school teams, organizes regional and national conferences, and hosts seminars and lectures to share best practices and inspire further action .
The program is a cooperative effort between the Senate Department for Education, Youth and Family and the association Freilandlabor Britz e.V., operating under the guidance of the Senate Department. (Ref. 1-4, 6)

The Olaya Herrera neighbourhood in Cartagena has been the focus of a series of projects that involve ecological restoration, environmental education, and community resilience building. These initiatives have centred around the restoration of the Ciénaga de la Virgen, an ecologically significant but heavily degraded coastal wetland bordering the neighbourhood. The primary goals of the projects in Olaya Herrera include the restoration of degraded mangrove ecosystems, mitigation of flooding and water pollution, strengthening community participation in environmental management, and promoting sustainable urban environments (ref 1, 2). The project is led by the EPA Cartagena, which coordinates actions such as collecting solid waste, planting timber trees and ornamental plants, and restoring green spaces that had become informal dumping grounds (ref 1). It also includes a community-led initiative called Los Guardabosques de Olaya that focuses on reforestation and environmental stewardship, it involves children, youth, and local mothers in reforesting mangrove areas around the Ciénaga de la Virgen. The community has established a mangrove nursery and employs innovative waste management practices, such as installing traps in canals to prevent solid waste from entering the Ciénaga (ref 2). The project also involves the private sector in 2022, the EPA led a campaign with local companies like Konfirma, Acuacar, and Pacaribe that focused on improving environmental health through the removal of 10 cubic meters of waste, promoting healthy living environments and fostering community participation in environmental monitoring and waste management practices​ (ref 4). Also, in collaboration with community leaders and local companies, the ANDI-TRASO Alliance supports large-scale reforestation and restoration activities in the southern parts of the Ciénaga de la Virgen adjacent to Olaya Herrera. The alliance plans to plant 40,000 mangrove seedlings (ref 6).

The Grand Parc des Aygalades project involves the creation of a 14-hectare metropolitan park (connecting Aygalades Park with Bougainville Park and François Billoux Park) that will connect the northern neighbourhoods of Marseille to the port located further south (Ref 1). This project is part of the green conversion of Marseille's northern districts, historically among the most disadvantaged areas in France (Ref 1). The Grand Parc des Aygalades project will enhance the city's greenery, reduce flood risks, create cool zones, restore and develop biodiversity, and significantly improve residents' quality of life and air quality (Ref 1, Ref 2). The environmental and social challenges include reconnecting the populations of these neighborhoods to green spaces, services, education, sports opportunities (Ref 2).
The park project includes redesigning urban infrastructure to improve rainwater absorption and reduce flood risks, addressing the issue of impermeable and artificialized soils that exacerbate flooding during heavy rainfall (Ref 1). It also involves renaturing a 17-kilometre-long stream currently buried under railway tracks, improving flood management and rainwater drainage (Ref 1, Ref 4). The project will also convert a heavily degraded former industrial site, requiring the rehabilitation of polluted soils (Ref 1). Additionally, creating green corridors aims to mitigate the heat island effect, particularly severe in these northern districts due to the high concentration of buildings and concrete surfaces, and the lack of green spaces. Public participation will be encouraged through information meetings, thematic workshops, and an online platform for submitting ideas and feedback (Ref 4).

The Oxygen Alley project, developed by the NGO Arboretum Detroit, is a green space located in the Poletown East neighborhood of Detroit. Spanning four formerly abandoned lots, the project, completed in 2023, serves as a significant environmental and community initiative aimed at improving local resilience and promoting environmental justice. Named in recognition of the closure of the Detroit waste incinerator—a major source of pollution for over 30 years—the project replaces a long-abused landscape with a thriving greenway that enhances both the ecological health and social well-being of the area.
Key features of Oxygen Alley include the planting of air-filtering trees and the creation of a shaded greenway lined with wildflowers, benches, and walking paths. This new green space not only provides a recreational area for residents but also functions as a natural air conditioner, stormwater sponge, and wildlife habitat. It addresses the neighborhood’s lack of tree cover, offering shade and cleaner air while helping mitigate the effects of climate change.
The project also underscores the neighborhood's longstanding struggle for environmental justice. The removal of 400 feet of asphalt and the remediation of a polluted landscape highlight the community’s efforts to reclaim and revitalize their environment. Oxygen Alley serves as both a functional green space and a monument to the residents’ victories over the waste industry, symbolizing their continued fight for clean air and livable spaces.
Supported by grants from the City of Detroit, Michigan Department of Natural Resources, and DTE Energy Foundation, among others, the project was brought to life through over 300 hours of volunteer labor. The creation of this greenway not only improves the neighborhood’s walkability but also offers a vision for a more sustainable and equitable future, serving as a model for urban revitalization projects across Detroit and beyond.
(Ref.1,2,3)

Eliseo Collazos is located in the coastal desert ecosystem of the Lomas or ‘fog oasis’, an area that receives less than 10 mm of rainfall per year. Vegetation cover is of particular importance in the hills surrounding Lima, as it provides critical solutions to erosion, landslides and soil degradation in the ecologically degraded ecosystem of the Lomas. However, this ecosystem is facing risks from urbanisation, illegal mining and agricultural practices, resulting in the lack of the delicate mist-fed greenery for which the Lomas are known (2). This has led to increased particulate matter in the air due to exposure to sand and wind, aggravating respiratory diseases such as tuberculosis, which is prevalent in Lima's informal communities (2).
Low-income communities have inhabited this area, forced to migrate from the rainforest, highlands and city to the desert slums (4), who have only been able to settle in these landscapes with little access to resources, prone to disaster risk, little public investment in infrastructure and little access to green spaces (2). As a result, these communities live in poor conditions (1). For this reason, in 2013, the University of Washington, under its Urban Informal Communities Initiative programme (1), initiated a participatory project that sought to address the challenges faced by the inhabitants of this area (1, 2). In a series of participatory workshops, residents identified greenspace and food security as top priorities in their community; the Gardens, Greenspace and Health project responds to these priorities as an initial step towards the expansion of greenspace, agriculture and ecological restoration in and around the Eliseo Collazos community (2, 4).
Although individual families constructed them, the front yard gardens contribute to a shared public realm and community greening (4). The general project also involved the installation of fog catchers and the creation of common recreational spaces (4).

The regreening project is located in Seestadt Aspern, a newly developed urban area in Vienna's Donaustadt district. Two years after the completion of buildings, streets, and squares, the ground was reopened in 2022 to address the challenges posed by urban heat islands. Pavement was removed, and trees and shrubs were planted to provide shade, create insect habitats, and open seepage areas for rainwater. Additional features like benches, a water station, and water jets were installed to enhance the area's livability. These measures improve the overall quality of life, offering residents green spaces to relax and opportunities to cool down through water play.
The project spans three connecting squares in Seestadt: Wangari Maathai Square, Simone de Beauvoir Square, and Eva Maria Mazzucco Square. In 2022, Wangari-Maathai-Platz and Simone-de-Beauvoir-Platz underwent intensive regreening. By 2023, Eva-Maria-Mazzucco-Platz in the Seeparkquartier was similarly transformed with additional greenery and cooling features. Under the slogan "Out of the Asphalt," one of Europe's largest and most innovative urban development projects took a significant step toward improving quality of life.
In 2023, over 1,100 square meters of asphalt were removed and greened. This effort included the creation of 12 new green beds planted with grasses, perennials, and shrubs. The design also introduced two square-like recreation areas with existing seating elements surrounded by green beds, providing shaded, pleasant spaces for relaxation.
The Eva-Maria-Mazzucco square was designed by a local NGO specializing in citizen engagement in urban development, while the project's overall initiation and implementation were led by the City of Vienna, the Donaustadt district, and Wien 3420 Aspern Development AG. This collaborative effort demonstrates how regreening initiatives can mitigate heat islands, foster urban biodiversity, and create more attractive, livable spaces. (Ref. 1-3)

In 2024, Ozanam (a housing private company) and the French Development Agency (AFD) formalized a partnership to modernize an ecological wastewater treatment plant in Saint-Joseph, a neighborhood in Fort de France. The project focuses on replacing an outdated 30-year-old installation that no longer meets current standards with a plant-based water filtration system based on the ‘Rhizosph’air’ patent. This innovative treatment process utilizes "filter gardens," which combine mechanical systems, a gravity network, and a phytoremediation approach. The system employs filters made of gravel and the roots of local plants, specifically Strelitzia reginae and Cyperus alternifolius, to naturally and effectively filter wastewater without odor (Refs 2, 3, 4).
The nature-based system purifies wastewater over an area of 2,000 square meters, with a capacity equivalent to serving 900 residents. This approach offers several advantages, including reduced maintenance costs due to its simplicity, decreased energy consumption compared to traditional treatment methods, and improved water quality released back into the environment (Ref 2). Beyond its technical efficiency, the filter gardens enhance biodiversity (Ref 2) by improving the quality of water discharged into the environment and providing habitats for various species. The solution also integrates seamlessly into the landscape, showcasing vibrant flowers native to the area (Ref 1).
Additionally, the project implementers plan to construct a walking path, provide recreational equipment, and install benches to encourage residents to utilize the area as a public green space (Refs 2, 5).

The city of Thessaloniki is tackling the energy crisis and climate change risks by prioritizing the installation of green roofs and green walls on school and municipal buildings as part of its resilience strategy, Thessaloniki 2030 (Ref 1, 2). One key project under this strategy has been implemented at EPAL Stavroupoli, one of the largest school complexes in the metropolitan area. The school, with a total built area of 11,918 sq.m and roof surfaces covering 6,042 sq.m, now includes a green roof covering 3,087 sq.m with 25,000 ground-cover plants, along with a vertical garden on three walls at the entrance, covering 100 sq.m and featuring 3,098 plants (ibid.).
The project is expected to yield multiple environmental benefits, such as reduced energy losses, improved thermal performance, enhanced sound insulation, better rainwater management, decreased runoff, and retention of harmful particles, all of which contribute to upgrading the area's green infrastructure (Ref 1). This initiative also strengthens the green fabric of western Thessaloniki and improves the local microclimate while addressing rainwater management issues (Ref 3, 4).