Some of the world\u2019s oldest cities have been contending with water since their earliest establishment. Rotterdam, The Netherlands\u2019 second largest city and home to the country\u2019s largest port, was one of the first in Europe to adopt and pioneer the \u201csponge city\u201d concept, developing its own \u201cwater-sensitive\u201d approach in the late 2000s, although its history with water goes back much further.<\/p>\n
\u201cRotterdam is a delta city that has always been dominated by water,\u201d says Dirk van Peijpe, co-founder of Rotterdam-based urban design firm\u202fDe Urbanisten. He outlines how the\u202fNieuwe Maas\u202f(New Meuse) river running through Rotterdam \u2013 a main distributary of Germany\u2019s Rhine and Meuse rivers \u2013 is just one part of the Rhine-Meuse-Scheldt delta in Rotterdam, along with several main branches of the Rhine including the\u202fWaal\u202f(main channel), the\u202f Nederrijn\u202f(Lower Rhine) and the\u202fLek to the east of the city.<\/p>\n
\u201cWater also has the potential to impact Rotterdam during storm surges from the North Sea on the western side of the city,\u201d he says.<\/p>\n
Responding to that ever-present influence and the exacerbating effect of climate change, De Urbanisten worked with the city on The Rotterdam Climate Adaptation Strategy, launched in 2013.<\/p>\n
\u201cThe question was how to adapt our city and protect our urban environment, not just using technical systems but to see if we could make our cities more adaptive and \u2018spongy\u2019 although the word wasn\u2019t widely used at that time. We just called it climate adaptation,\u201d he says.<\/p>\n
The strategy triggered multiple interventions across the city. These included the development of water storage, including 10,000m\u00b3 capacity storage under Museum Park, as well as over 130,000m\u00b2 of green roofs \u2013 with an overall target of 1M.m\u00b2 by 2030.<\/p>\n
Innovative typologies such as water squares \u2013 blending functionality with local amenity \u2013 were developed, one of the more prominent being Benthemplein Watersquare, which opened in late 2013. The square provides a drainage system to take pressure off Rotterdam\u2019s sewers by acting as a temporary public storage basin for rainwater during heavy storms.<\/p>\n
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Benthemplein Watersquare, Rotterdam, was designed by De Urbanisten to prevent sewage overflow during heavy rainfall by collecting runoff from surrounding streets and roofs. It features collection basins that work as recreational spaces when dry.<\/p>\n
Another noteworthy scheme was Keilehaven\u202fTidal Park in the Merwe-Vierhavens area, completed in 2024, transforming a former industrial harbour into a green recreational amenity. It is designed to act as a sustainable, climate-adaptive public space that reintroduces a tidal, estuarine system into an urban setting.<\/p>\n
De Urbanisten is also leading the design of the Rotterdam High Line or Hofbogenpar. Construction on the 2km elevated park, located on a former railway viaduct, was scheduled to start in 2025, with opening for public use planned for 2027.<\/p>\n
\u201cThere, rainwater is very much part of the system,\u201d van Peijpe explains. The structure will function as a purifying system for rainwater using solutions such as reed bed filters, before storing it in aquifers. \u201cThe result is a circular system now being implemented in Rotterdam,\u201d says van Peijpe.<\/p>\n
He adds that De Urbanisten is also involved in \u201ca long-term research and design initiative that asks the question \u2018What if sea levels rise by around 2m in 2100?\u2019 Because then you pass the threshold at which we can still rely on the water safety system as we have it now.\u201d<\/p>\n
Flooding and drought mitigation measures are also part of the history of Denmark\u2019s capital. City of Copenhagen director of climate adaptation and the lead on Copenhagen\u2019s Cloudburst Management Plan Jan Rasmussen says the city began engaging with climate adaptation in its modern form in 2007.<\/p>\n
He vividly recalls reading an Intergovernmental Panel on a Climate Change report which at that time predicted a 30% rise in rainfall and more frequent cloudburst events for Denmark.<\/p>\n
\u201cIn 2008, we made the first analysis about the impact of climate change in Copenhagen and in 2010, we prepared the Climate Adaptation Plan, which was launched in 2011,\u201d he says.<\/p>\n
As fate would have it, the plan proved eerily timely. As it was being launched, what Rasmussen describes as \u201ca monster rainfall\u201d hit Copenhagen on 2 July 2011, causing $US1bn (\u00a3750M) of damage in two hours and triggering over 90,000 insurance claims. The estimated cost to insurers was between DKK4.9bn and DKK6.2bn (\u00a3567M-718M), which significantly impacted local insurers and global reinsurers.<\/p>\n
\u201cThat\u2019s why we prepared the Cloudburst Plan in 2012. The flood event had been so massive that we quickly understood that it was not possible to expand the existing sewer system to handle that amount of water. So, we wondered how we could climate-proof the city so we would not experience that again.<\/p>\n
\u201cWe developed some typologies to build a plan for the entire city using the roads and green spaces to store the rainwater, and that led to a plan including more than 200 surface projects for streets, parks and boulevards.\u201d<\/p>\n
One intervention is at St. Anna\u2019s Square in Copenhagen\u2019s historic centre, which was transformed into a multifunctional cloudburst management site, designed to handle extreme rainfall and prevent flooding. It features sunken green areas \u2013 or cloudburst boulevards \u2013 that manage water on the surface, diverting it away from vulnerable buildings while also creating recreational spaces.<\/p>\n
Karens Minde Park was also transformed into a sponge city area, capable of catching and storing 15,000m\u00b3 of rainwater to prevent floods. A soccer field at a higher corner of the park is the first of many \u2018stages\u2019 within it, capturing piped water that runs from an uphill area down to the soccer field, Rasmussen explains. \u201cAs rainfall continues, the water runs down to fill a lake and if that lake is filled, it runs down towards the park\u2019s entrance. We built a wall around the entire park and a gate so that if that area is filled with water, the gate automatically closes.\u201d<\/p>\n
Drought and water shortages were also part of the strategy. \u201cWhile drought has not historically been a problem due to an abundance of groundwater in the city, it is likely to be a challenge in the future. Maybe in 10 to 50 years, there\u2019ll be a lack of groundwater, so we have to do something about it,\u201d says Rasmussen. \u201cThe first priority is to avoid damage from rainwater, but number two is to figure out \u2013 can we reuse some rainwater?\u201d<\/p>\n
Enghaveparken is another Copenhagen \u201csponge\u201d park, featuring 22,600m\u00b3 of water storage capacity to manage cloudbursts. A specific 2,000m\u00b3
retention chamber collects daily rain to clean streets and water plants, integrated with recreational areas.<\/p>\n
Financing the DKK 11bn (\u00a31.3bn) Cloudburst Management Plan was so significant that it required updated legislation to enable water tariffs.<\/p>\n
Copenhagen lobbied for a change of national legislation to fund new infrastructure adaptation measures, with technical adaptations financed by utilities charges or water taxes by Greater Copenhagen Utility, which supplies drinking water, district heating, city gas and cooling. Meanwhile, aspects of the programme relating to urban space improvements would be financed through the city\u2019s municipal budget.<\/p>\n
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Enghaveparken is a Copenhagen \u201csponge\u201d park, featuring 22,600m\u00b3 of water storage capacity to manage cloudbursts. A specific 2,000m\u00b3\u202fretention chamber collects daily rain to clean streets and water plants, integrated with recreational areas. Credit: City of Copenhagen<\/p>\n
Full engagement<\/strong><\/p>\n Arup global water business leader Mark Fletcher notes that sponge city interventions \u2013 particularly given the complexities of older, established cities \u2013 require broad-based thinking and planning.<\/p>\n This proved critical when Arup won an international competition to develop a stormwater management and drainage masterplan for Shanghai, China in\u202f2019.\u202fThe aim was to develop a \u201cblue\/green\/grey\u201d approach to manage stormwater and improve urban drainage across 640km\u00b2 to address urban flooding, pollution and climate change. Arup partnered with the Shanghai Urban Construction Design & Research Institute to create the winning proposal.<\/p>\n \u201cWhen we first looked at Shanghai, governance was a real issue, and one of the real strengths of that project was bringing everyone together. We got all the parties together and did workshops where we said \u2018Okay, who\u2019s responsible for this? Who\u2019s responsible for that?\u2019 We got them starting to talk to each other.\u201d<\/p>\n Arup won an international competition to develop a stormwater management and drainage masterplan for Shanghai in 2019, to address urban flooding, pollution and climate change. Credit: Derek Lee<\/p>\n In the UK context, a move towards broader, system- or catchment-level approaches is helping drive wider implementation of water management interventions, he says. And he notes that the government\u2019s launch of updated national standards for Sustainable Drainage Systems (SuDS) last June signalled\u202fa major shift away from traditional underground, pipe-based drainage towards surface-level, nature-based solutions.<\/p>\n \u201cThat\u2019s about \u2013 is there something that you can do in the catchment or the city so that we get less water that goes into the pipe? If we take everybody on board across the catchment or in the city and everyone\u2019s working together on it, all those pieces start to come together.\u201d<\/p>\n Flood Ready London\u202f(formerly the London Surface Water Strategic Group), which encompasses the Greater London Authority (GLA), Thames Water, the Environment Agency and London Councils, published the\u202fLondon Surface Water Strategy last May.<\/p>\n Fletcher notes that it includes an initiative that incentivises utility companies to install SuDS such as\u202frain gardens when refilling the approximately 165,000 holes dug annually in London.<\/p>\n \u201cIt\u2019s essentially saying \u2013 when we dig up a road or when we dig up a footpath, why do we always put impermeable materials back? Why don\u2019t we put things back that might help us?\u201d<\/p>\n He points out that the amenity created by \u201csponginess\u201d provides a useful pathway towards positive community engagement.<\/p>\n \u201cThe sponge city concept is not a silver bullet. It doesn\u2019t solve everything, but it does improve resilience to regular flooding, and you get the added benefit of better biodiversity and public green space. The point is that there are multiple benefits, not just flooding, that come out of this solution rather than just sticking pipes and pumps in.\u201d<\/p>\n WSP fellow, landscape advisory Ludo Pittie describes strategies such as those adopted by Rotterdam and Copenhagen \u2013 along with many international examples \u2013 as \u201cfoundational\u201d blueprints for \u201cthe international understanding that the way we design our cities has to change\u201d.<\/p>\n Successfully implementing that change lies, at least partly, in adhering to an overarching framework, something that has increasingly been a point of difference in London\u2019s latest efforts.<\/p>\n \u201cIn the UK context, we have been leading on the SuDS Master Plan for Westminster City Council [developed 2024-2025] with Thames Water and we\u2019ve also worked on the London Surface Water Strategy, which was the first time such a plan was developed across the entirety of London at a strategic level.<\/p>\n \u201cUp until recently, what you\u2019d had is a lot of London boroughs doing their individual surface water management plans. And this was the first time there was an aggregated London-wide perspective on bringing all of that together across catchments.\u201d<\/p>\n Progressive developers are also influencing the picture, he says, citing Barking Riverside in East London, where a flood-prone brownfield site has been used to build a resilient, sustainable community using advanced SuDS.<\/p>\n Key features include storing 100% of surface water runoff in parks to prevent Thames flooding, rising ground levels per\u202fThames Estuary 2100 guidelines, and using permeable paving, green roofs and swales to improve water quality.<\/p>\n \u201cWe\u2019ve seen a lot of developments that we\u2019ve worked on that include those principles, where private developers will take the lead and adopt those green infrastructure networks from the outset.\u201d<\/p>\n Thinking big <\/strong><\/p>\n Beyond London and initiatives such as the SuDS Master Plan, Pittie believes sponge cities would benefit from a nationwide approach \u2013 citing the way SuDS are now mandated for new developments in Wales.<\/p>\n He questions whether England\u2019s delay to the implementation of Schedule 3 of the Flood and Water Management Act 2010 \u2013 the legislative framework designed to mandate the use of\u202fSuDS\u202fin new developments across England and Wales \u2013 is where the problem lies. Despite being enacted in Wales in 2019, delays to implementation have continued elsewhere, partly due to concerns from developers regarding increased costs and regulatory burdens.<\/p>\n \u201cI wouldn\u2019t necessarily say Schedule 3 delay is the reason we don\u2019t have sponge cities. But I think sponge cities should be a top-down national policy.<\/p>\n When it becomes a national policy framework, moving forward with implementation becomes a lot easier because there\u2019s a mandate for it.<\/p>\n \u201cI think we have an opportunity to bring everything together in terms of policy and implementation. I think especially with AMP8 [Asset Management Period 8] and the next period too, we\u2019re going to see even more action towards bringing that to bear through the catchment management plans.\u201d<\/p>\n The government\u2019s New Towns programme is also \u201ca huge opportunity\u201d, Pittie says. \u201cIf you\u2019re designing something new, you can do it in a much more streamlined way. It\u2019s possible \u201cto really incorporate those green infrastructures from the outset, and that translates from principles at the masterplan stage to the concept drawings, to how you draw the cross sections with engineers, to how you then do the detailed design.\u201d<\/p>\n With flood risk bringing direct implications for mortgage lending, property valuation and insurance, Pittie argues that the financial sector\u2019s continued engagement is also critical, pointing to \u201cvaluable work\u201d by the Flood Action Coalition. Established last\u202fNovember by insurer Aviva and change-making organisation The Conduit \u2013 WSP is also a member \u2013 the aim of the coalition is to scale finance with the goal of creating a billion-pound bond for flooding.<\/p>\n \u201cI think we\u2019re okay,\u201d Pittie says of the UK\u2019s overall score card. \u201cThere\u2019s been a lot of work done since The\u202fFlood and Water Management Act in 2010. More can be done for sure, but a lot of the plans we\u2019re seeing are continuing to move that dial. It\u2019s about what policy changes are required regionally, but also how we start to enact and finance those and bring the right partners together to start to deliver some of these schemes at scale.\u201d<\/p>\n Kongjian Yu The pioneer of Sponge Cities Kongjian Yu \u2013 pictured at left with friend and colleague global water business leader Mark Fletcher in Beijing last June \u2013 died aged 62 on 23 September 2025. Media reports confirmed that he was killed in a plane crash in Mato Grosso do Sul state, Brazil, while reportedly filming a documentary about his work. The urban designer, landscape architect and Peking University professor\u2019s untimely death followed his inclusion in the opening programmme of the S\u00e3o Paulo International Architecture Biennale, which aligned with COP30 in Bel\u00e9m in November 2025 through its focus on climate-resilient urbanism. ArchDaily described Yu\u2019s passing as \u201ca profound loss to the fields of landscape architecture and environmental sustainability\u201d, adding that \u201chis legacy and transformative ideas will continue to shape cities for generations to come\u201d.<\/p>\n![\"\"](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2026\/03\/B_01_03_Shanghai_City_Scape_3-c-Derek-Lee.webp.webp\")
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\n12 May 1963 \u2013 23 September 2025<\/p>\n