A large number of synergies and cost-efficiencies can be achieved when rainwater management is integrated into overall urban planning. Cities around the world are increasingly concerned with improving their resilience against the costly effects of climate change. Addressing climate change and creating climate resilience in cities, includes building resiliency in city water supply, reducing the risk of flooding from cloudbursts or storm surges with nature-based solutions and water basins as well as ensuring wastewater infrastructure can withstand the increasing pressure that climate change puts on sewers and treatment plants. We have gathered 12 such cases, which make cities more climate-resilient and more livable at the same time.

1. Stormwater solutions with multiple purposes, Roskilde, Denmark

Good collaboration between many parties is necessary to find unconventional solutions. This approach led to a new stormwater storage solution in the city of Roskilde. The storage tank serves a double purpose as a recreational facility for skaters. Close cooperation was successfully achieved between all the stakeholders, consultants and subcontractors to get the unit to function optimally for different purposes and simultaneously comply with the technical specifications. The example proves how climate-resilient and climate adaptation projects can contribute to creating livable cities of the future. (Courtesy: Nordarch, City of Roskilde and COWI)

2. Enghaveparken, Climate Park, Denmark

With Enghaveparken’s location at the bottom of a hill, the park has become a strategic location in the handling of extreme rain. The task the team was given was to find space for 22.6000 m3 of rainwater in the park, while honouring the simplicity of the park’s historical design. The transformation of the park has turned the water challenges into a variety of new experiences for recreation and interaction. When it rains within normal measures, the rainwater from the nearby roofs will be led to the park and to a retention basin. Here, the rainwater will be stored and used for watering a diverse range of plants and trees during dry spells and can even be used to clean the streets of Copenhagen.

Enghaveparken Climate Park received the coveted award ‘Årets Arne’, a regional prize named after architect Arne Jacobsen. The award is given by the Danish Association of Architects to a project that significantly heightens the quality of Danish architecture.

3. Climate street absorbs rainwater, Copenhagen, Denmark

In an attempt to avoid floods caused by cloudbursts, one of Copenhagen’s streets, Helenevej, has been transformed into a climate street with infiltration of rainwater. Asphalt has been replaced with tiles to allow rainwater to seep through the surface. The rainwater is thereafter infiltrated on its way to the groundwater aquifers. Gaps between the tiles transport the water below the road surface. The tiles and the joints are designed to infiltrate a maximum amount of water without losing their carrying capacity. There is a reservoir consisting of 40 cm of gravel beneath the tiles. In case of extreme rainfall, the water is retained in the reservoir beneath the surface. The gravel layer has a pore volume of 30% which means it can absorb up to 30% water. Along the road, the water can flow between four chambers. It is possible to connect the chambers to the sewerage system in situations where for instance the surface is frozen and therefore keeps water above the surface. The road has proved able to handle large water volumes without problems during a cloudburst. (Courtesy: Frederiksberg Utility, Frederiksberg Municipality, NCC, IBF and University of Copenhagen)

4. Kampung Admiralty, Singapore

Kampung Admiralty has won World Architecture Festival Award 2016, Skyrise Greenery Award 2017 and World Building of the Year 2018 . It is the first development in Singapore to integrate housing for the elderly, and hence Singapore’s flagship vertical village. The design of the Hydrological system allows for over a million gallons of tap water to be conserved each year as storm water runoff is stored in the rainwater harvesting tank and reused for irrigation.

The focus of the project is to encourage the elderly residents to engage in an active lifestyle among younger generations, but it is also part of a greater effort to increase environmental sustainability.

Ramboll (Ramboll Studio Dreiseitl) is responsible for design of the greenery and landscape, which includes a tropical rainforest, as well as water management systems.

5. The Lakeside Garden, Singapore

Once a mangrove swamp, the Jurong region in South-Western Singapore is being transformed into a vibrant business and leisure destination known as the Jurong Lake District. The Lakeside Garden, the first phase of the Jurong Lake Gardens, serves as the recreational heart of the new district. Led by Ramboll, the project emphasises water-sensitive urban design and ecosystem regeneration. The Lakeside Garden has restored the area’s swamp forest and wetlands, blending nature with recreation through community-focused features such as nature-themed play areas and allotment gardens. The project prioritises wildlife habitat enhancement by maintaining tranquility within the gardens and provides accessible green spaces and recreational amenities for residents, fostering both environmental conservation and community building.

(Courtesy: Ramboll)

6. Climate-resilient Green Bus Stops, Poland

Green Bus Stops are part of a holistic approach to climate-resilient cities. Many cities today suffer from Urban Heat Island effect (UHI) and excess of rainwater runoff in the streets. Four cities in Poland have chosen to use the so-called Green Bus Stop as a Nature Based Solution to reuse rainwater as a resource and contribute to the reduction of UHI effect. Each bus-stop is covered with a plant-based green roof with a water retention layer – such a roof stops up to 90% of the stormwater falling on its surface. During dry weather, the water is used by the plants and evaporated, making space for the next fallout. Part of the water, which is not used on the roof, together with the excess stormwater from the surrounding sidewalk, is retained in a vegetated retention-infiltration box in the back of the shelter. Green Bus Stop emits less heat than the traditional counterpart does, at times as much as 10°C less. Read more from Amphi Consult.

7. The climate resilient school, Roskilde, Denmark

The vision for the climate resilient school in Roskilde is to handle all stormwater on campus. To ensure this, 1,100 m2 of roof has been disconnected and runoff from the pavement infiltrates through permeable pavings. Runoff from the roof runs through trenches into a paddling pool shaped like the local bay which is also used by the schoolchildren for playing and learning. From the ‘bay’, the stormwater goes through an ACO trench into a soakaway. The soakaway has a membrane underneath, creating storage volume for stormwater. It is possible for the children to pump up the stormwater with old-school hand-pumps. The overflow goes into a rain garden and a ditch downstream through the rain garden. From the rain garden, the water flows into a multifunctional pump track lane with parkour elements for street climbing. The multifunctional square is covered in permeable rubber and illustrates the meeting between the coast and the sea. The project demonstrates that SUDS are able to handle everyday rain, design storms and cloudbursts when the different SUDS elements are connected to each other as pearls on a string. (Courtesy: Danish Technological Institute, Aalborg University, DHI, Gundsoe Entreprenoer Forretning, Thing og Brandt Landskaber, IBF, NCC Roads, ACO Nordic, Wavin, Nykilde, Amphi Consult, KLS Grafiske Hus, Municipality of Roskilde and Roskilde Utility)

8. Hydraulic models for flood protection strategy, Prague, Czech Republic

After a severe flood in 1997 the Czech government adopted a flood protection strategy. The Prague Flood Model, developed by DHI water experts, was part of the strategy. Emergency plans for Prague city centre and the suburbs were updated based on model results, the weakest points in the flood defences were identified and suggestions for improvements were assessed. Based on those analyses, the first phase of flood protections for the Old Town was designed and implemented in 2001. Just one year later, in 2002, Prague experienced its worst floods in history, and the model showed its value in guiding the response of the city authorities. They were able to close mobile barriers at the right time and place, to save lives as well as protecting the historical Old Town. The model has since been reassessed and updated regularly and has been used for the design of the complete flood protection system as well as in urban planning, including the drawing up of risk maps as required by the EU Flood Directive. Three years ago, an interactive tool, Operational Flood Maps, was introduced and has successfully been in operation since then. It is connected to eleven city water level gauges and enables the City Hall Crisis Management Department to estimate and forecast the extent of flooding. (Courtesy: DHI)

9. Copenhagen’s first climate-resilient neighbourhood, Denmark

Unlike most of Copenhagen, the neighbourhood of Skt. Kjelds quarter in the North-Eastern part of the city is sitting on an incline, sloping down towards the harbour. Therefore, the main purpose is to retain surface water in the area and infiltrate as much rainwater to the groundwater as possible.  The overall aim for the neighbourhood is to have flexible surface solutions that can manage daily rainfalls locally. During cloudbursts, the surface solutions are combined with a conventional split rainwater sewer system, which ensures a
controlled transport of the rainwater to the nearest harbour. The transformation has been carried out in different sections:

Taasinge Plads
The transformation of Taasinge Plads was completed in 2014. The area is now a green pocket park that demonstrates how to manage three different types of surface water fractions: Rainwaterfrom roofs, which is used for recreational use and play, rainwater from zero traffic areas, which is used for local infiltration and finally, surface water from roads, which is infiltrated through filter media. As salt is used as ice control in the winter, the road water does not infiltrate the groundwater, but is transported to the harbour. During cloudbursts, an integrated open storage capacity is taken in use and works as a blue element in the pocket park.

Bryggervangen and Skt. Kjelds Plads
Bryggervangen and Skt. Kjelds Plads was finished in 2019 and is a long stretch of road (34,900 m2 and a roundabout), where green spaces, urban nature and linked surface water solutions have replaced asphalt and pavements. The applied urban nature is inspired by the characteristic wet/dry biotopes found in Copenhagen and uses their processes in a rational way to treat and retain rainwater. Surface water from roads is handled by first-flush solutions, which direct the polluted initial surface runoff (first flush) stemming from heavy rainfall to the existing sewer system, whereas the cleaner, ‘second flush’ is directed to green surface water solutions. This can be turned off in the winter to avoid salt intrusion into the green areas.

(Courtesy: City of Copenhagen and HOFOR (Greater Copenhagen Utility). Strategic design advisors for the master plan of the area: THIRD NATURE. Advisors for Taasinge Plads: LYTT Architecture and WSP. Advisors for Bryggervangen & Skt. Kjelds Plads: SLA and NIRAS.)

10. Evaluation of flood management in Malmö, Sweden

The nature-based stormwater solution in Augustenborg, Malmö, includes open canals, swales, ponds, green roofs and adapted levelling of green areas to ensure controlled flooding. This area was retrofitted with an open green stormwater system in the late ’90s. Since this retrofit, it was unclear whether the solution was effective for extreme rainfall events with a 100-year or higher return period.

When a major rainstorm hit Malmö in August 2014, Augustenborg was less affected by flood damage than nearby areas, prompting an evaluation of its flood management system.

A model of the system was set up using the simulation software MIKE FLOOD, including rain-on-grid and infiltration, to enable accurate quantification of stormwater infiltration in green areas. Scenarios were created for the current stormwater system and the previous system. This methodology allowed for a comparative evaluation of the two. Results showed that the retrofitted green stormwater system would result in approximately 80 % lower discharge, thus substantially decreasing the risk of flooding.

(Solution provider: DHI)

11. Combining climate adaptation and social sustainability at Karen’s Minde Axis, Copenhagen, Denmark

The Copenhagen district of Sydhavn, a densely populated low-lying area by the harbour, faces challenges from rainwater backing up from the backlands, causing damage to both natural and built environments. Karen’s Minde Axis project, focused on climate adaptation and urban space enhancement, addresses this issue by integrating rainwater retention into parks, urban spaces, and natural areas. A 2,500 m² rainwater basin not only prevents flooding but also enhances biodiversity, significantly increasing the variation in fauna species.

This project takes a holistic approach, creating synergies across sectors while preserving the existing framework as much as possible. Serving as both a recreational space and a flood prevention area, Karen’s Minde Axis exemplifies how local climate adaptation can improve social cohesion and enrich community narratives.

(Solution provider: Schönherr)

12. Playful cloudburst management at Lindevang School, Frederiksberg, Denmark

At Lindevang School, the schoolyard is not just a space for play but also a vital water storage area. Redesigned to adapt to cloudbursts, the yard features two lowered areas with underlying storage membranes, enabling it to hold more water from the school and surrounding roads. When these membranes are full, water rises in the lowered spaces, which also serve as innovative play areas, functioning as stairs, seating, and even a small football field. The renovation has also improved growing conditions for existing trees, with additional trees planted to enhance water infiltration in the schoolyard.

(Solution provider: Niels Lützen Landsskabsarkitekter)