Urban flooding (stormwater)

As an industrial city under climate change, Birmingham has been confronted with multiple environmental risks such as air pollution, fluctuating precipitation and flooding (Ref 3). The Big City Plan is a 20-year city center regeneration plan to support Birmingham’s sustainable transformation, where the delivery of the Eastside City Park was prioritized (Ref 1, 2). Completed and opened to public in 2013, this first new park in Birmingham for 130 years is a linear site which connects the city center along the frontage of Millennium Point eastwards towards the Digbeth canal. (Ref 1, 4, 5). Providing 2.73 ha of urban green spaces, the multi-award winning development features more than 300 trees, a 110 meter canal water feature and a public square with 21 jet fountains, and offers “a moment of green in a journey through the city” (Ref 1, 6).

Lafayette Greens is a transformative urban green space and community garden located in downtown Detroit, occupying a parcel of 1720 sqm that once housed the historic Lafayette Building. Following the building's demolition in 2010, the site, situated near Compuware headquarters and the Detroit Federal Building, was re-imagined through a public-private partnership into a productive urban garden (Ref.1, 6). The garden was designed in 2012 for a local software company, Compuware, which after completion gifted it to a local NGO, The Greening of Detroit, in 2014. Lafayette Greens serves as a green oasis in a bustling urban environment, offering city workers, residents, and visitors a space to relax and engage with nature. The garden produces chemical-free fruits, vegetables, herbs, and flowers, and since 2019, has focused on cultivating a certified pollinator habitat, essential for supporting urban biodiversity. The garden also provides educational programming, including classes on pollinators like bees and birds, and the DIG - Detroiters in the Garden series, in collaboration with Fort Street Presbyterian Church’s Open Door program, fostering community involvement and environmental stewardship. (Ref.2)

The Dublin Urban Rivers LIFE (DURL) project incorporates two interconnected wetlands in Griffeen Park as part of its broader initiative to improve water quality, natural water management and aquatic biodiversity in urban areas. These wetlands were specifically designed as a natural sewage system to treat wastewater from the surrounding areas, addressing a significant environmental issue known as "domestic misconnection." Domestic misconnection occurs when household appliances, such as washing machines, dishwashers, and kitchen sinks, are incorrectly linked to surface water drains rather than the sewage system. This leads to untreated wastewater being directly discharged into local waterways, contributing to contamination.
In the River Griffeen catchment, which includes approximately 12,000 dwellings and associated infrastructure, domestic misconnections are a considerable threat to water quality. The DURL project focuses on identifying and rectifying these misconnected appliances to ensure that wastewater is properly treated before entering the river. This process will not only improve water quality but will also provide flood alleviation and support healthier aquatic ecosystems in the area.
The project is aligned with broader environmental policies, including the River Basin Management Plan 2022-2027, the Water Framework Directive, the Climate Change Action Plan, the Floods Directive, and the draft Biodiversity Plan. One of the key strategies is to use a Geographic Information System (GIS) to streamline inspections for domestic misconnections, making the process faster and more cost-effective.
The constructed wetlands in Griffeen Park, with a standing water depth of approximately 30 cm, are planted with a variety of native Irish species. These wetlands offer a natural, sustainable solution to wastewater treatment, with the potential for similar applications across Europe. (Ref. 2, 4)

The Three Mile Creek Greenway Trail project aims to transform the existing creek into a valuable community asset by developing a multi-use greenway trail (Ref 1). This greenway will connect various parts of the city through walking and biking paths, linking neighbourhoods, parks, and commercial districts while providing access to unique natural areas (Ref 2). The creek having been adandonned for decades (Ref 5), the initiative seeks to turn 3 Mile Creek (3MC) into a vibrant natural corridor that fosters recreation, education, and economic activities (Ref 1, Ref 2). The project aims also at reducing pollutants in the waterway, restoring natural stream channels, and maintaining flood protection (Ref 1).
The 3MC Greenway Trail is expected to become a key feature of Mobile's urban landscape, offering numerous benefits. These include enhancing community health, both mental and physical (Ref 2), and stimulating the local economy by increasing property values, tax revenues, and opportunities for recreation-related businesses and job development (Ref 2). Additionally, the trail will improve community connectivity by linking neighbourhoods, parks, and schools, thereby fostering a stronger sense of community and better access to public spaces (Ref 2). Lastly, the project will contribute to environmental restoration through stormwater management, pollution reduction, and natural habitat preservation (Ref 2).
The greenway is part of a plan to restore the health of the Three Mile Creek watershed and is the first major piece of a long-term Mobile Greenway Initiative (MGI) (Ref 4).

The Mziuri Park in the center of Tbilisi and adjacent to the city's zoo was heavily impacted by floods and landslides that occured in June 2015 in Georgia. As a result, many of its facilities were destroyed, necessating the redevelopment of the site (Ref. 1,2). In 2017, the Georgian government initiated the Urban Reconstruction and Development (GURAD) Project with funding from the European Investment Bank (EIB) under the 100 million € framework loan. The park's reconstuction is one of multiple projects under the natural disaster recovery component of the GUARD Fund (Ref. 1,2). As of 2020, the park has been fully redeveloped catering to the needs of diverse groups, but especially youth and children with a number of different sports, cultural and recreational areas (Ref. 3,4). Importantly, construction was carried out under consideration of spatial adaptation measures for people with disabilities and with a renewed drainage system to mitigate the effects of future floods (Ref. 1). The park is now again one of the most important recreational areas in Tbilisi (Ref. 3).

The NatureRx Rain Garden Pilot is a community-driven initiative aimed at addressing urban runoff and its associated challenges, implemented by Bí URBAN, a community hub and social enterprise in Dublin focused on urban regeneration. The pilot project developed in Stoneybatter, Dublin involves diverting rainwater from residential rooftops into specially designed rain gardens (1). The area is used as the first trial area by installing around 100 rain gardens (3, 11). Built to fit neatly into available spaces, these self-sustaining planters will filter rainwater through the garden, with overflow pipes in place to prevent flooding during heavy downpours (1).
It is expected that these gardens will transform sterile urban spaces into green areas, enhancing biodiversity, providing habitats for pollinators, and acting as carbon sinks (1,3).

Birmingham faces several immediate risks due to climate change, including heatwaves, water shortages from droughts, floods, and extreme weather (Ref 11). To address these challenges, Birmingham City Council has set a goal to reduce carbon emissions by 60% by 2027. As part of this effort, the new Birmingham Library project, initiated by the council, includes a rooftop garden designed to contribute to this target (Ref 3). The library was designed by the Dutch firm Mecanoo Architecten, with a design process spanning from 2008 to 2012 (Ref 5). The two outdoor rooftop gardens, located on levels 3 and 7, were completed in 2013 (Ref 1). These gardens provide green spaces in the city center, enhance water management through rainwater harvesting, serve as educational facilities for sustainable food innovation, and create natural habitats for wildlife (Ref 1, 3, 4, 6). Their contributions helped the library achieve a BREEAM 'Excellent' rating and have garnered various awards (Ref 1, 10). The new library aligns with Birmingham City Council's Big City Plan to regenerate the city center, with the green roof gardens playing a key role (Ref 4).

As part of the development of the neighbourhood around Opaltorget in Tynneryd, Gothenburg, a park has been thoroughly renovated. The area is being developed and renovated as part of a long-term, large-scale project to become more attractive, safe, and sustainable [Ref. 1]. The area has previously been classified as an exposed area, indicating socio-economic problems and relatively high crime rates [Ref. 7, 8]. The old park was considered an important part of the neighbourhood but was sometimes perceived as being unsafe or being used mainly as a passage area. The renovation aims to make the park safer, more attractive, and more accessible to residents [Ref. 1, 3]. The new park includes a playground, recreational areas, rainwater management and a diverse tree population promoting the delivery of several ecosystem services [Ref. 2]. Around the park, new residential buildings and a kindergarten have been constructed, and the adjacent square, a central spot of the neighbourhood for business and social interactions, has been renovated [Ref. 2, 4, 8, 10]

The Sacred Heart Church, a historical landmark in Detroit's Eastern Market since 1875, faced persistent stormwater and surface flooding issues. The church's parking lot, once marked by cracked concrete and stagnant water, has been transformed through an innovative Green Stormwater Infrastructure (GSI) retrofit. GSI leverages natural processes to manage stormwater, using plants to absorb, retain, and slow runoff. This retrofit, a collaboration between The Nature Conservancy and the parish, stands as one of Detroit's largest GSI projects at a faith-based institution. By introducing bioretention gardens filled with native plants, the project manages runoff from 1.4 acres of impervious surfaces and diverts 1.5 million gallons of water annually from the sewer system. This green space not only mitigates flooding and reduces combined sewer overflows (CSOs) but also provides a cooling effect, enhances community recreation, and significantly cuts the parish's drainage charges by 49%.(Ref.1,2,3)

The Africatown Heritage House Bioswale is a gently sloping green space with multiple functions which include catchment of runoff water and filtration of pollution in the runoff water (Ref 2), erosion control (Ref 2), and creation of habitat for biodiversity (Ref 1). It also has an educational purpose for students and the local community (Ref 2) and contributes to overall beautification (Ref 5).
The Bioswale was built by Birmingham-Southern College’s Environmental Center (Ref 6) and developed through the collaboration between the Mobile County Commission, the Mobile Area Lodging Association, Mobile County Training School, Mobile County Training School Alumni Association, and the National Academies of Science (NAS) Gulf Research Program (Ref 2). The project aims to address heavy rainwater management (Ref 5) and drainage issues (Ref 3).