Green space creation and/or management

In May 2020, CityLAB Berlin launched "Gieß den Kiez", an interactive platform designed to support Berlin's urban trees by fostering collaboration between citizens and the city. The platform enables voluntary civil society efforts to help water the city's endangered tree population. It features a map that visualizes nearly all of Berlin's street and park trees, complete with data such as water requirements, age, and species. Citizens can create profiles, adopt trees, and mark them as ‘watered’ within the app, making it easy to track contributions to the health of Berlin’s trees. (Ref. 2)
Berlin's trees face growing challenges due to increasing temperatures, reduced rainfall, and exposure to road salt in winter. The hot summers of 2018 and 2019 highlighted the urgency of supporting the city’s trees, which provide cooling shade, clean air, and habitats for numerous animal and plant species. To address this, "Gieß den Kiez" was developed as a platform where authorities, volunteers, and civic society could collaborate to prevent tree dehydration.
The platform maps over 625,000 trees across Berlin and offers additional tools, such as rainfall data from the last 30 days and the locations of public water fountains, which can be used for watering trees. By connecting data from city authorities, the German Weather Service, and OpenStreetMap, the fully open-source platform allows for transparency and accessibility in its operation. (Ref. 6)
The project has proven highly successful in Berlin, with over 10,000 participants actively watering trees, and its model has been adopted in other German cities like Leipzig. "Gieß den Kiez" not only exemplifies a practical response to urban climate challenges but also fosters a sense of shared responsibility and community engagement in caring for urban green spaces. (Ref. 6)

The project focused on implementing multilayer blue-green roofs in four Italian cities—Cagliari, Palermo, Perugia, and Viterbo—as part of a broader European initiative to address climate change impacts in urban environments (1,3). Spearheaded by a collaboration between multiple Italian universities and the Dutch company Metropolder, the project began in 2019 (1,3). The primary goal is to enhance urban resilience by integrating green infrastructure capable of mitigating climate-related urban hazards such as flooding and heat waves, which are increasingly severe due to climate change and urbanisation (2,3).
The multilayer blue-green roofs combine the ecological benefits of traditional green roofs with an added water storage layer, allowing them to retain rainfall and manage runoff effectively (2,3). This dual function helps reduce pluvial flooding and the urban heat island effect, while also improving thermal insulation in buildings (2,3). Each installation was planted with low-maintenance, climate-adapted vegetation, and equipped with sensors to monitor ecohydrological and thermal performance over several years (1,3). These roofs are capable of retaining up to 100% of rainfall from significant events, thereby easing the burden on urban drainage systems and contributing to climate adaptation in Mediterranean cities (2,4).

The urban garden in Miraflores park (Huertas las Moreras) was established already in 1991 on an old waste dump and contains 10500 m2 of plots for locals to grow fruits and vegetables [Ref. 1]. The creation of the gardens was initiated by citizens who formed an association and implemented it in cooperation with the City of Seville. The citizens were discontent with the lack of green space in the area, and the urban gardens came to be alongside Miraflores Park, which was also pushed by the locals. The initial goals of the gardens were to allow locals to produce their own food and to host educational activities [Ref. 2]. More recent developments exemplify the focus on education and knowledge. In 2022, the citizen science project "Planta Bienstar" was carried out in the gardens, where high school students measured the lead levels in the soil and crops. The project aimed to investigate if lead levels posed a health risk and if the gardens could reduce levels over time. The project was organised by the non-profit Descubre Foundation and funded by the foundation and the regional Government of Andalusia. The project relied on the knowledge and efforts of the citizens, the students and gardeners in an intergenerational collaboration where the young could learn methods from their elders [Ref. 3, 4].

In 2022 an afforestation initiative was implemented near a landfill located in the Tutora commune (1 - 6). Organized by the City Hall of Tutora, the event brought together representatives from the regional government of Iasi County, the "Asociația de Dezvoltare Intercomunitară pentru Salubritate" (ADIS), and volunteers from SC Girexim SA, SC Salubris Iasi, and Edil Industri Iasi. Together, they planted 2,000 acacia saplings, donated by the Forestry Directorate of Iasi (6). The afforestation action took place under the umbrella of the regional environmental campaign "Iasi Mai Verde" (Iasi More Green), led by the County Council of Iasi. This campaign promotes a range of eco-friendly activities, including educational programs in schools, waste cleanup events, and afforestation initiatives in partnership with ADIS, while actively encouraging the support and participation of local municipalities from across the region (1, 3, & 7).
"Iasi Mai Verde" aligns with national environmental strategies such as the Ministry of the Environment's "Curățăm România" (Let's Clean Romania) and the annual Planting Forest Month (3 & 6).
On the same day, as part of the Iasi Mai Verde initiative, students from a local school in Tutora were given a practical education workshop on how waste management operates at the regional level. The students were also invited to witness the afforestation action and participate, fostering a deeper understanding of environmental stewardship (1- 5).
The newly planted trees are acting as a natural barrier, and help improve air quality by filtering dust, pollution, and waste particles originating from the nearby Tutora landfill. In turn, this contributes to better living conditions for the residents in close proximity to the landfill, enhancing both their health and overall quality of life (5).

The Cagliari Canal project is an initiative aimed at revitalizing and transforming the urban and natural landscape of the Cagliari Metropolitan Area in Sardinia. The project is rooted in the city's strategic metropolitan plan and seeks to restore and enhance the navigability of the Terramaini-La Palma canal, which had become disused and neglected over time​ (3,4). The primary goal of the Cagliari Canal project is to develop a connected, innovative, and sustainable urban environment by re-establishing the canal as a green and blue infrastructure​ (2). It aims to provide alternative, sustainable mobility options, improve connectivity between municipalities, and enhance the natural and urban environments. It strives to foster a sense of community by creating a shared space for residents and integrating modern amenities that align with environmental sustainability (1,4). It involved a highly participatory process, emphasizing community involvement from the initial planning stages. The Metropolitan Authority of Cagliari, in collaboration with local stakeholders, launched a series of consultations to gather public input on the canal's design and function​(3). These consultations were part of a broader initiative called LabMet, the Metropolitan Laboratory for Innovation, which facilitated the collection of ideas and feedback (1). The project was partly developed in response to the increasing environmental challenges faced by Cagliari, including the need to adapt to climate change. The canal's revitalization is seen as a key measure for enhancing the city's resilience to climate-related risks, such as flooding and heat waves​(1). By restoring the canal and its surrounding areas, the project aims to mitigate these risks through improved water management, reducing pollution, and the creation of green spaces that can absorb excess rainwater and provide cooling effects​ (2)

Located between the Rotes Rathaus, Karl-Liebknecht-Straße, Nikolai Quarter, Spreeufer and the television tower, the old founding centre of Berlin is one of the capital's most important urban open spaces. This open space between the TV tower and the Spree is being redesigned on the basis of an international open space planning competition and many years of public participation. With further development, this touristically significant location in the historic centre of Berlin will undergo a climate-resilient redesign and upgrade with great design and functional quality. (Ref. 1)
The listed areas of the Rathausforum and the Marx-Engels-Forum will in future be connected to form a continuous ribbon of open space that runs from Alexanderplatz to the Spree. Central areas will be unsealed and green spaces will be created that can be used in a variety of ways, which will also be attractive places to spend time and improve the microclimate. Trees and shrubs will be planted on already existing and new green areas. The aim is to respectfully consider the numerous visible and hidden historical references and at the same time transform the site into a sustainable urban open space that combines a high quality of recreation, sustainability and culture. Next to plants, a new rainwater management system is being implemented that stores rainwater and uses the created green spaces to evaporate water. Playgrounds and a water fountain are further additions to a new recreational area. (Ref. 3; Ref. 4; Ref. 5)
The project is characterized by a years-long participation process. Around 10.000 citizens participated in feedback rounds, workshops, dialogues, and information sessions in which they could voice they wishes and ideas for the area. The project is implemented and organized by the state-owned company Grün Berlin, which engage with various stakeholders since 2015. Preparations for the construction start in late 2024 and the project is expected to be finished in 2030. (Ref. 5; Ref. 9)

For thousands of years the Rio Salado, also known as the Salt River, and its larger mainstem, the Gila River, served as an important perennial source of life and growth for indigenous people residing in central Arizona, including the Akimel and Piipaash (3). Today, the Salt River is an ephemeral river corridor connecting diverse urban communities across an expansive and growing Maricopa County (3). While the river is now typically defined by intermittent flow as a function of water conservation and distribution in an arid urban climate, it also has powerful flows during the Arizona monsoon season providing a diverse and unique ecosystem for the region (3). To foster the health of the River, a regional multi-decade project was initiated in 2018 called Rio Reimagined, which includes six cities and two tribal communities (1). Rio Reimagined is a planning initiative in a very early concept stage, centered around the mission to support and enhance this treasured river corridor (3). The goals of Rio Reimagined consist of connecting communities, Equitable & Sustainable Development, and Restoring and Revitalizing Healthy Rivers (3). As part of the Rio Reimagined, the City of Phoenix founded a collaborative project called Rio PHX that will help promote a 20-mile Rio Salado (Salt River) corridor as a local and regional destination that attracts positive investment for the benefit of existing/future businesses, residents, and tourists (1). The final aim with this project is to improve health outcomes for existing and future residents by address outstanding needs in the area and create opportunities for housing, employment, recreation, art, and ecological restoration (1). From May 2024 to May 2025 Rio PHX will engage in creating a community profile, an existing conditions assessment, community engagement & visioning, developing implementation strategies and drafting the master plan (1). Public hearings and final plan adoption are set to take place in fall 2025 (1).

This project involves collaboration among government, private, and educational entities focused on developing an agroforestry initiative that integrates economic activity, labor market integration, and educational opportunities for young children at the “Foyer de l’Espérance” [school and child welfare center] in Fort-de-France. The objective is to plant 1,500 cacao trees on the Foyer's premises by 2025. These trees will serve as pedagogical support for teachers and children. Planting activities commenced in 2022, and the first cacao pods are expected to mature in 2-3 years. Subsequently, these pods will be processed and transformed by the Martinican Lauzéa chocolate factory under the brand “Chocolat de l’Espérance” (Refs 2; 4).
The idea for this project emerged in June 2022 when young students engaged in a discussion about cocoa farming with Thierry Lauzéa during "Business Thursdays," organized by “Espérance Formation Insertion.” These meetings allow young beneficiaries to explore the business world and discuss their career paths with professionals. During one of these sessions, the young participants inquired about the origins of the cocoa used in Lauzéa's chocolates, leading to the concept of producing cocoa for the Frères Lauzéa company (Refs 3; 5).

The former Kulturpark Plänterwald, once the only permanent amusement park in the GDR, closed in 2001 due to declining visitor numbers. Over time, the 23-hectare site became a ‘lost place,’ falling into disrepair. In 2014, the state of Berlin reacquired the area, and two years later, Grün Berlin initiated its redevelopment with a sustainable development concept that places significant emphasis on rainwater management.
The project’s goal is to avoid discharging rainwater into the sewer system and instead manage all precipitation on-site. This approach addresses both heavy rainfall events and extreme drought conditions, creating a sustainable rainwater management system. A central element of this concept is the historic but dried-up water basin located near the iconic Ferris wheel. Plans include redesigning and reactivating the basin, incorporating terraces and a shallow water zone, transforming it into a key part of the rainwater cycle while providing an attractive recreational and adventure area. (Ref. 1; Ref. 2)
In the future, the water basin will no longer be purely decorative but will serve as a critical artificial water reservoir. To support this function, it will be equipped with a natural horizontal filter system featuring reeds for rainwater purification. Pre-treated water will flow into the newly designed 3,000-square-metre basin near the Ferris wheel. Rainwater collected in the basin, along with water stored in cisterns throughout the park, will irrigate the site’s vegetation. This innovative approach ensures sustainable water use and contributes to the ecological revitalization of the park. (Ref. 1; Ref. 3)
By integrating sustainable rainwater management into its redevelopment, the former Kulturpark Plänterwald is being transformed into a resilient and environmentally conscious space, combining historical preservation with modern ecological practices.

The Far West Detroit neighborhood faces significant challenges with its aging infrastructure. The neighborhood’s stormwater and sewer systems are combined into a single system that is only capable of handling a limited volume. During heavy rain events, the system's capacity is exceeded, causing excess stormwater and untreated sewage to overflow into the Rouge River, which negatively impacts the environment (Ref. 1).
Detroit is investing $40 million in a transformative stormwater management system in the Far West neighborhood near Rouge Park. Described by the Detroit Water and Sewerage Department as the largest project of its kind, it will redirect 98 million gallons of rainwater and snowmelt into two new detention basins and a renovated sewer system. The new wastewater system is expected to significantly reduce water volumes in Detroit’s combined sewer system during heavy rainfall and to provide flood relief for approximately 1,200 homes that have experienced flooding in recent years. This expansion, informed by community feedback, marks one of the city's most notable investments in green infrastructure to improve its overextended wastewater management system.
The project has been planned through extensive studies and community coordination since 2016, with construction set to occur in three phases, extending through 2026. Crews broke ground on the South Basin, North Basin, and sewer overhaul in July 2022, and progress is reportedly on track. In addition to the basins, the stormwater management initiative includes neighborhood improvements to enhance recreational opportunities for residents and visitors alike. Planned enhancements in Rouge Park will introduce wetland spaces with native flora, creating greener, more inviting areas in the community for residents to enjoy (Ref. 2).