We have gathered 12 implemented examples of multifunctional solutions that create more resilient and liveable cities across the world.
Traditionally speaking, climate adaptation seeks to lower the risks posed by the consequences of climate change, including flooding caused by extreme rain events. However, when approached holistically, climate adaptation can also be used to create synergies between a number of urban challenges by addressing several areas of urban development at the same time. A large number of synergies and cost-efficiencies can be achieved when rainwater management is integrated into the overall urban planning, and cities around the world are increasingly concerned with improving their resilience against the effects of climate change, including reducing the risk of flooding and cloudbursts. We have gathered 12 of such cases, which make cities more 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 lead 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 at the same time comply with the technical specifications. (Courtesy: Nordarch, City of Roskilde and COWI)
2. Bishan – Ang Mo Kio Park, Singapore
Integrating stormwater opportunities with urban planning is highly relevant in tropic and sub-tropic regions. A good example is the rehabilitation of the Kallang River within Bishan – Ang Mo Kio Park in Singapore, where an existing concrete stormwater canal was changed into an attractive and accessible natural river ecosystem, still securing the flood protection. The inaccessible canal was transformed into a liveable city waterscape for the joy of the local residents. (Courtesy: Atelier Dreiseitl / Ramboll)
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 its 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 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. Water brings life to Bishan-Ang Mo Kio Park, Singapore
In 2006 the ‘Active, Beautiful, Clean Waters Programme’ (ABC Waters) was introduced in Singapore. The purpose was to transform the country’s water bodies beyond their functions of drainage and water supply into lakes with new spaces for recreation. The Bishan park project is one of the flagship projects under this programme. The park was due for major refurbishment and the Kallang River, which at the time was more a concrete channel along the park edges, was also due for an upgrade in order to accommodate increasing volumes of rainwater runoff from the catchment due to urbanisation. Today, the 2.7 km long straight concrete drainage channel has been restored into a sinuous, natural river and 62 ha of park space have been redesigned to accommodate the dynamic process of a river system including fluctuating water levels, while at the same time providing maximum benefit for park users. Since the introduction of the naturalised river into the park, the park’s biodiversity has increased by 30%. (Courtesy: Ramboll Studio Dreiseitl)
5. Treating rainwater through curb-extensions, Copenhagen, Denmark
On Lindevang, a street in Copenhagen, an unconventional management approach to rainwater from roads has been applied. A technology that is becoming more widespread in relation to cleaning dirty runoff water from roads is SUDS. By using alternative methods for handling road water, a double profit is gained in the form of a decreased load on the sewer system and a facility with recreational value. The curb-extensions on Lindevang are constructed by using a two-section system in which the first section collects fallen leaves and sand particles. The second section of the curb-extension infiltrates through a special type of soil which binds and delays organic and inorganic nutrients, through which clean water infiltrates into the groundwater aquifers. In the case of extreme rain events, the water is by-passed to underground infiltration trenches in order to use the full capacity of the system and then followed by discharge to the sewer. (Courtesy: Orbicon)
6. Flood protection with advanced pumping solutions, Saint Petersburg, Russia Saint Petersburg Flood
Prevention Facility Complex is the principal line of defence in protecting the beautiful Russian city against flooding. The complex involves dams and related hydraulic structures extending over 25.4 kilometres (15.8 miles) and comprises two navigation passes with approach canals, six water gates, eleven protective dams and a six-lane highway with a tunnel, bridges and road interchanges passing over the protective dams. When a flood threatens, the dock chambers fill with water, the floating gates rise to the surface and are moved to the middle of the navigable canal reducing the impact of the storm surge on the Neva Bay water area. When the flood danger recedes, the floating gates are led back into the docks and the water is pumped out. The draining of the dock chambers is executed by advanced pumpingequipment installed at each of the pump stations at the Northernand Southern sides of the navigable canal. All the pumps feature a special design and the pump stations are located in cast-insitu reinforced concrete framing below the water line. (Courtesy: Grundfos)
7. Rainwater reuse systems of green rooftops serve dual purpose, Copenhagen, Denmark
Rainwater can be collected off rooftops and reused for multiple purposes. In an office building called ‘House of Energy’ located in Copenhagen, rainwater is collected and reused for irrigation of the green areas on top of the building’s reception and parking lot. A drainage system diverts the rainwater to four basement tanks (of 1,500 litres each) placed in the parking area. To ensure the irrigation of the green roofs, an automatic water system has been installed. This type of rainwater solution reduces the volume of stormwater runoff and decreases the stress on the sewer systems. The amount of energy needed to moderate the temperature of the building is reduced by the green areas due to the cycle of condensation and evaporation. As a result, the daily energy demand for air conditioning on sunny days is reduced. (Courtesy: Genvand)
8. Stormwater solutions, Fornebu, Norway The former Fornebu International
Airport in Norway closed in 1998 and has been transformed into a green and active residential area and public park with water as an important visual element throughout. The Nansen Park, a new section of the Fornebu park, was completed in 2008 and includes solutions for the managing of stormwater, green structures with gutters, cleaning ponds, retention basins and an outlet to the sea. (Courtesy: COWI)
9. 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 raingarden and a ditch downstream through the raingarden. From the raingarden, 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 coast and 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)
10. 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)
11. Copenhagen’s first climate resilient neighbourhood, Copenhagen, Denmark
An existing neighbourhood in Copenhagen is currently undergoing a transformation to become more resilient against coming climate changes like strong and heavy cloudbursts. The transformation will also result in green, beautiful urban spaces for the local residents to enjoy.
Unlike most of Copenhagen, the neighbourhood of Skt. Kjelds Kvarter is sitting on a slope, sloping down towards the harbour. The main purpose is therefore to retain surface water in the area and infiltrate as much rainwater to the groundwater as possible. Storage capacity is used during heavy rain. During cloudbursts the excess water is transported away from the neighbourhood to places where the risk of damage is minimised. The overall aim for the neighbourhood is to have flexible surface solutions that can manage daily rain 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 will be carried out in different sections – two of those sections are described here:
The transformation of Taasinge Plads was completed in 2014 and the area is now a green pocket park that demonstrates management of three different types of surface water fractions; rainwater from roofs, which is used for recreational use and play, rainwater from none traffic areas, which is used for local infiltration, and finally surface water from roads, which is infiltrated through filtermedia (as salt is used for ice control in the winter, the road water is not infiltrated to the groundwater but 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 is a long stretch of road (34,900 m2) where green spaces, urban nature and linked surface water solutions will replace asphalt and pavements. The applied urban nature will learn from characteristic wet/dry biotopes in Copenhagen and uses their processes in a rational way to treat and retain stormwater. Surface water from roads is handled by First-Flush solutions which direct the polluted initial surface runoff (First Flush) of a rainstorm to the existing sewer system, whereas the cleaner “Second Flush” is directed to green surface water solutions. (Courtesy: City of Copenhagen and HOFOR (Greater Copenhagen Utility). Strategic design advisors for the master plan of the area: Tredje Natur. Advisors for Taasinge Plads: GHB Landscape Architects and Orbicon. Advisors for Bryggervangen & Skt. Kjelds Plads: SLA and ALECTIA.)
12. Energy efficiency and integrating water for a liveable city, Nanjing, China
Sustainable urban development plans for the Nanjing High Tech Zone on the west bank of the Yangtze River in China were designed to make the semi-developed area greener and more attractive for both businesses and citizens. The concept was to rethink and upgrade urban planning in the area to shift the development in a more sustainable and innovative direction, while at the same time safeguarding the growth of the city and ensuring its climate resilience. Solutions that would improve existing town plans, reduce energy consumption and create a greener and more healthy environment were developed in cooperation with Danish urban water experts. As a result, the water infrastructure of the city was transformed from occupying ugly technical-looking structures to being an integrated part of city life. The newly developed structures are used as green areas, recreational spaces, transport corridors for soft traffic, rest places, wetlands for water treatment and so on. At the same time the capacity of the water transportation and storage areas has increased making the city more climate resilient. (Courtesy: COWI)