Urban flooding (stormwater)

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 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)

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).

The Helmut Zilk Park, named after the late Mayor of Vienna, is located in the heart of the city, near the central train station. Surrounded by newly constructed residential and office buildings, the park serves as a vital green space, offering a variety of amenities. From playgrounds and sports fields to a community garden and cafés, it provides a space for social interaction and recreation. The park is characterized by large open meadows, which function as rainwater seepage areas, and features over 500 trees along its pathways., as well as community gardens. Flower groves enhance the park’s visual appeal while also providing habitats for local wildlife. The natural edges of the park create a diverse urban biotope that supports various plant and animal species. Grass and meadow communities have been carefully planned to enhance biodiversity and provide wet, humid habitats that help infiltrate rainwater from the surrounding paved areas. Already in its first year, the park has become home to insects, small animals, and even larger species like rabbits and snakes, contributing to its rich ecosystem.
The park was developed by the local municipality of Vienna on a site that was once part of the city's railway track system. It is the largest park the city has created in the past 40 years, designed to serve as a recreational area for both local residents and travelers using the nearby train station.
This project is part of a broader urban development initiative around the former Southern Railway station, led by Austria’s Federal Railways Company (ÖBB) and the City of Vienna. The plans included residential housing, office spaces, social infrastructure, and the creation of the Helmut Zilk Park.
Spanning approximately 70,000 square meters, the park stands as the largest public green space created in Vienna in four decades. The central area of the park features a large lawn, perfect for picnics, ball games, and recreational activities. (Ref. 1, 2, 3, 8)

The Dog River Watershed Restoration project aims to protect and enhance the chemical, biological, and cultural integrity of the Dog River Watershed in Mobile County, Alabama (Ref 1). Guided by the Dog River Watershed Management Plan (WMP), the project addresses key issues such as pollution, litter, stormwater management, and habitat degradation (Ref 2). Funded by the National Fish and Wildlife Foundation's Gulf Environmental Benefit Fund and completed in partnership with stakeholders, the project focuses on implementing targeted restoration activities to improve water quality, protect critical habitats, and increase public awareness and access to the watershed (Ref 2). The Dog River Watershed faces significant hazards, including pollution, sedimentation, erosion, and the impacts of urban development (Ref 3). These challenges are intensified by the watershed’s role as an urban estuary, where land use heavily influences water quality and habitat conditions (Ref 3). To mitigate these threats, the project incorporates pollution prevention measures, shoreline restoration efforts, and community engagement initiatives (Ref 4). By prioritizing scientifically supported actions and aligning with broader environmental goals, the project seeks to restore ecological balance and ensure the long-term health and resilience of the watershed and its connected ecosystems in Mobile Bay (Ref 4).
The Watershed Management Plan for the Dog River Watershed is a key component of the Mobile Bay Shore Habitat Conservation and Acquisition Initiative, which focuses on acquiring, restoring, and preserving habitats and wildlife species affected by the environmental disasters of the Deepwater Horizon oil spill that occurred in 2010 (Ref 6). The project spans three critical areas: 300 acres in the Dog River Watershed (as detailed in this project profile), 450 acres within the Three Mile Creek Watershed, and 40 acres in the Garrows Bend Watershed (not in focus here) (Ref 7).

Since the 1980s, the Graefekiez neighborhood in Berlin's Friedrichshain-Kreuzberg district has been a traffic-calmed area where all road users are treated equally, driving is limited to walking speed, and cars are permitted to stop anywhere. However, this once-progressive concept no longer functions effectively due to the significant increase in cars and delivery vehicles over the years. The streets no longer resemble a traffic-calmed zone, with traditional layouts featuring roadways, sidewalks, and parking spaces. As a result, many users fail to recognize the traffic-calmed nature of the area, leading to safety issues: vehicles drive too fast, delivery traffic causes conflicts, and streets are difficult to navigate safely.
Berlin’s transport sector faces the challenge of meeting legally mandated CO₂ reduction targets. Achieving these goals requires bold measures, including limiting private motorized transport (MIV), especially in densely populated areas where residents and visitors have access to alternative modes of transportation.
The "Graefekiez" project addresses these challenges through urban redevelopment aimed at improving livability and promoting sustainable urban mobility. Car parking has been banned from the streets, freeing up space for communal use such as lounge areas. As part of the "Graefekiez" project, the district office is converting parking spaces into green spaces and expanding tree disks to adapt to the climate and promote a sponge city.
The project was developed collaboratively with residents and NGOs through a participatory process led by the Friedrichshain-Kreuzberg district office, in partnership with the Berlin Social Science Center and Paper Planes e.V. Implementation began in 2023 on Graefestraße and Bockhstraße.After a six-month trial period, the district office decided in 2024 to make the measures permanent.
This initiative advances a safer, greener, inclusive urban environment while meeting climate and community goals. (Ref. 1, 2, 3)

The park called Järnvågsparken will be constructed in the developing neighbourhood of Masthuggskajen as the main green space of the area, measuring about 8000 m2. The park will offer recreational activities for people living and working in the area, with spaces designated for rest, meetings, picnics, walking and play. For example, there will be a large playground, many different places to sit, grass lawns and a space to host cultural events in [Ref. 1-4]. The park will also be designed to manage stormwater and reduce flood risk [Ref. 5, 6]. The park will be built over an existing highway, turning it into a tunnel while reconnecting the new neighbourhood. The remaining future park area next to the road are currently parking spaces [Ref. 1, 4, 5]. The adjacent streets will also see more greening, increasing the connectivity of green spaces and mobility [Ref. 4-6]. The location on top of a tunnel limits the soil depth of the park, but the ambition is still to house a rich plant and animal life, including trees, providing ecosystem services [Ref. 1-6]. The project is managed by the City of Gothenburg [Ref. 1, 7].

The Three Mile Creek Hydrological Restoration project is taking place in one historic channel of the Three Mile Creek, located east of Dr. Martin Luther King, Jr. Avenue, and covering approximately 1,800 linear feet (Ref 3). This project, led by the City of Mobile, aims to remove sediment from the stream channel. This segment of the Creek was bypassed with a straight channel in the early 1980s to control flooding in the area, thus accelerating the accumulation of sediments in the historic channel (Ref 1).
The project's goal is to restore and maintain the natural flow to the historic channel and create a connection to the City and County's Blueway initiatives (Ref 3). This will improve habitat conditions and water quality and help to protect the area’s estuarine and marine water resources (Ref 8). It will also contribute to revitalizing the Three Mile Creek Watershed and provide increased recreational opportunities for citizens, like kayaking and canoeing (Ref 6). Construction work occurred in 2022 and 2023 (Ref 3).
The Three Mile Creek Hydrological Restoration is a key component of the Mobile Bay Shore Habitat Conservation and Acquisition Initiative, which focuses on acquiring, restoring, and preserving habitats, including riparian, wetland, and upland areas that support various fish and wildlife species affected by the environmental disasters of the Deepwater Horizon oil spill that occurred in 2010 (Ref 1). The project spans three critical areas: 450 acres within the Three Mile Creek Watershed (as detailed in this project profile), 300 acres in the Dog River Watershed, and 40 acres of bay shore property in the Garrows Bend Watershed (with the latter two areas being part of separate initiatives) (Ref 4).

Maskinparken is a new park covering 3700 m2 in the Lindholmen district, a new neighbourhood in a previous industrial/harbour area [Ref. 5]. The park is described as a well-needed green oasis or green lung in the developing area. The park finished construction in 2022 and is intended to provide access to green space for people living and working nearby. It is also designed as a blue-green stormwater management solution, where about 500 m3 of rainwater can be stored in the lower areas during heavy rainfall. Stormwater will be leaked from surrounding grey areas to the park to protect them from flooding. The Swedish National Board of Housing, Building and Planning (Boverket) has highlighted the park as a good example of climate adaptation in urban planning. The park has a variety of plants such as different tree species and flowering meadows, and plants that can withstand being soaked in the lower areas. Plants can grow in different landscape structures, such as hills and a pergola. The park also has amenities such as benches and lights, which are designed to mirror the style of the surrounding, older industrial brick buildings [Ref. 1-4].

Two new wetlands were established in Dodder Valley Park as part of the Dublin Urban Rivers Life Project (DURL). This project aimed to create integrated constructed wetlands (ICWs) at strategic locations in South Dublin County to purify wastewater and storm-water before it discharged into rivers.
The ICWs consisted of a series of cells resembling shallow ponds, typically 200 to 300 mm deep. Heavily planted with specific vegetation, these cells treated water by removing nutrients and harmful impurities, resulting in cleaner, purer water being discharged. The water flowing into the wetlands came from wastewater of misconnected appliances and storm-water pipes located under public roads, which collected rainwater from roads, footpaths, and the roofs and patios of houses.
These wetlands also provided important benefits, including flood alleviation, bioretention of particulates and nutrients, improved habitat conditions, and enhanced biodiversity. The project aimed to promote the relationship between green infrastructure and public well-being, creating a complex biological system that supports a diverse range of plants, animals, microorganisms, and hopefully attracts frogs, newts, and birds.
To increase native biodiversity, the wetlands were designed with pollinator-friendly plants and trees, making them visually appealing for park users and the public. A Wetland Planting Day took place on September 9, 2022, with over 40 participants, including residents and representatives from local organizations. This phase of the project fulfilled not only the objectives of the LIFE project but also those of the River Basin Masin Management Plan 2022–2027, the Water Framework Directive, the Climate Change Action Plan, the Floods Directive. (1, 2, 5)