City infrastructure (e.g., reduced flooding, improved water quality)

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)

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)

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).

Arizona is experiencing an unprecedented drought, now nearing 15 years and surpassing the most severe drought in over 110 years of recorded history (1). For Phoenix residents, accustomed to extreme heat and minimal rainfall, rising temperatures are bringing new health risks (3). Diminished rainfall not only leads to water scarcity but also raises temperatures, as the sun’s energy, instead of being absorbed to evaporate moisture, intensifies the heat on the ground (2). In 2023 alone, extreme heat claimed at least 147 lives, with Arizona seeing the majority of these fatalities. By early August, over 100 heat-related deaths had been reported in the state (2).
In response to these challenges, the Watershed Management Group (WMG) has collaborated with Arizona State University’s Sustainability Teachers’ Academies to develop a program that maximizes the desert’s limited rainfall to build community resilience (3). Their Schoolyard Water Education Program brings educational services to Phoenix schools, focusing on designing and installing rain gardens as part of outdoor learning initiatives (3). This hands-on approach transforms schoolyards into interactive laboratories where students learn the principles of sustainability through direct engagement with their surroundings (3).
A project at Clarendon Elementary School in Phoenix involved constructing a rain garden with native plants and wood chip mulch to help retain moisture (3). These gardens offer students a living classroom, where they can observe seasonal changes in native plant life, distinguish beneficial species from invasive weeds, and track rainfall to measure the garden’s water intake from rooftops and direct rain (3). Beyond the academic learning, rain gardens provide cooler, safer spaces for students to gather, fostering a lasting connection with nature and a deeper understanding of sustainable water practices (3).

This project aims to increase water retention capacity in the landscape around urban areas and promote biodiversity by restoring wetlands and natural streams in the forested areas on the island of Hisingen in northern Gothenburg. Many wetlands and streams in the area have been drained or otherwise affected by human activity, reducing biodiversity, increasing the risk of floods and droughts and causing greenhouse gas emissions from peatland. The goals of the project are to reduce the risk of floods downstream, reduce the effects of dry periods, increase groundwater infiltration and benefit species living in and around wetlands and streams in the forest [Ref. 1-3]. The Swedish Anglers Association has initiated the project in cooperation with the City of Gothenburg and the environmental engineering company Miljöteknik I Väst AB [Ref 1]. The project's first stage is a continuation of an earlier project to make an inventory of wetlands and their status [Ref 1, 2]. For the second part, 6,9 ha of wetlands and streams on land owned by the city were restored [Ref. 1, 3]. The project will lead to further efforts in wetland restoration around Gothenburg [Ref. 2, 4].

The Fenkell Stormwater Project in the Brightmoor neighborhood of Detroit is an initiative led by the Detroit Water and Sewerage Department (DWSD) to mitigate the impact of heavy rain events on the local sewer system. By transforming 92 Detroit Land Bank Authority (DLBA) parcels into 24 bioretention gardens, the project aims to significantly reduce street flooding and basement backups in the area. These gardens, spread across approximately 50 acres of mostly vacant land, utilize permeable soils and landscaping techniques to absorb excess rainfall, which helps prevent the overloading of the city’s combined sewer system. This is particularly important in reducing combined sewer overflows (CSOs), which occur when the system's capacity is exceeded during heavy rains, leading to untreated stormwater and sewage being discharged into the Rouge River.
The project is expected to manage and treat about nine million gallons of stormwater annually, making a significant impact on both the neighborhood’s infrastructure and the environment. In addition to the bioretention gardens, the project includes the partial removal of Blackstone Street between Keeler and Midland streets to further enhance stormwater management.
Community engagement has been a critical component of the project, with residents of Brightmoor and Minock Park participating in meetings to share their preferences for the types of trees, plantings, and other features. The DWSD will maintain the gardens under its Green Stormwater Infrastructure (GSI) program, which already includes 19 other similar projects across the city. The project is currently in the construction phase and is expected to be completed by the end of 2024, modernizing Brightmoor’s stormwater infrastructure and providing long-term environmental and community benefits.
(Ref.1-3)

MINI Ireland, in collaboration with conservation charity Earthwatch Europe, has launched Ireland's first "Tiny Forest" at the Tolka River Project, a community-driven rehabilitation program in Co. Dublin. In a space the size of a tennis court (195m²), nearly 600 native trees have been planted, creating a densely packed, environmentally efficient green area.
This partnership with Earthwatch aims to raise awareness for local environmental projects and foster community bonds. Green spaces like this offer valuable areas for people to connect with nature, exercise, unwind, and reduce stress—one reason the Tolka River Project center was chosen as an ideal location. "Tiny Forests" are remarkable for their impressive efficiency within a small footprint: by planting 600 native trees closely together, the forest grows naturally with increased density, achieving up to 30% more plant density, ten times faster growth, and up to thirty times better carbon dioxide absorption. Over the next three years, this forest is expected to attract more than 500 animal and plant species, transforming into an accessible mini-ecosystem.
The project uses a variety of locally sourced native trees, including silver birch, alder, hazel, hawthorn, and gorse, which together will form the natural layers of a forest. Ireland's first Tiny Forest was planted on March 22, 2023, at the Tolka River Project site in Dublin's Buzzardstown area. The Tiny Forest, located near the center, will serve as a space for reflection and recovery, supporting clients on their journey to rehabilitation. The planting event was a day of celebration, with Tolka River Project clients and MINI Ireland staff working side-by-side to create this thriving green space.. The space is utilized to create recovery-focused programs, including mindfulness and yoga, while functioning as a social gathering area (7).

The schoolyard at Reginhard Primary School in Reinickendorf faced persistent challenges, often becoming unusable due to poor drainage. After rainfall, water would pool, leaving the yard submerged and inaccessible to the 400 primary school pupils. Even in dry weather, the schoolyard was far from ideal: a lack of play equipment made it uninviting, and in summer, the area became excessively hot, offering little comfort or shade. Both children and the school community, including teaching staff and parents, voiced a strong desire for improvement.
Adding to the urgency for redesign, Berliner Wasserbetriebe imposed a discharge restriction, requiring rainwater to be managed on-site. This led to a comprehensive transformation of the school grounds. Large areas were unsealed, allowing water to seep naturally into the ground. Underground seepage systems were installed to enhance drainage, and the redesign introduced green spaces, a school garden, and near-natural play and exercise areas. These changes not only resolved the flooding issue but also created a more inviting and sustainable environment for students.
The focus on ecological and sustainable design improved the microclimate, providing cooler surroundings and enabling outdoor breaks filled with activity and fresh air. The redesign transformed the schoolyard into a vibrant space that meets the needs of both children and the environment.
This project was funded by the Berlin Programme for Sustainable Development (BENE Umwelt) and financed by the European Regional Development Fund (ERDF). (Ref. 3; Ref. 4)

This series of projects in the Trinity Garden aims to improve sports fields, enhance drainage, and replace HVAC (Heating, Ventilation, and Air Conditioning) systems at the community center in the Trinity Garden community (Ref 1). The first project involves a complete renovation of the playground area at Trinity Gardens Park. The entire playground will be rebuilt with a new drainage system, along with the installation of a new play structure, benches, and trash receptacles (Ref 2). Another key component of the project includes the construction of a new natural baseball/football combo field, with a new infield, bases, outfield fencing, foul poles, and with improved drainage (drain piping, inlets, sodding, and irrigation) for the sports field (Ref 3). On the subject of recreation and public health, Councilman Fred Richardson emphasised the significance of Trinity Park, stating, “Good public parks are key to creating healthy children and, in turn, strong communities. I am so happy that we are able to bring these major improvements so local children will have a great place to come play, and their caregivers will have a place to watch them from” (Ref 2).
Additionally, another major project on the agenda focuses on street and drainage improvements within the community. This will address issues on Warsaw Avenue and Collins Avenue, from Main Street to Jessie Street, aiming to resolve several hazardous open ditches that currently run through the neighborhood (Ref 2).