Sponge Cities and River Deltas: Flood Control by Working with the Land.
In many ways, 2021 has been the year of fire and floods. Between the west coast and southern Europe being constantly under a haze of smoke and torrential rains washing away huge areas around the world, fire and water have defined many people’s lives.
Which might be why this summer I received the oddest media request I’ve ever had. A random person on the phone from Washington DC asking if I could appear on her nightly news program to talk about the floods in China and their Sponge Cities initiative.
I agreed without knowing what was to follow, so imagine my family’s delighted laughter when they realized I was going to be appearing on Chinese State Media’s nightly US news broadcast to talk about the floods that had washed away entire villages in Hunan province and what cities across China were doing to prepare.
It was, perhaps, the oddest 6 minutes of my life.
It’s worth remembering that far, far more people die and are displaced every year by floods than by fire, despite fire being more dramatic. Preparing for floods – be they monsoon rains, sea level rise, hurricanes and typhoons, or just above normal rain fall – should be job number one for any municipality that is serious about resilience.
Several cities in China are doing just that.
The sponge city idea being implemented by China isn’t new. The designers drew on Sustainable Drainage Systems (SuDS) and Low Impact Development ideas from the UK and North America and took them to their logical conclusion.
First described by Professor Kongjian Yu in 2013, Sponge Cities are a way of diverting the enormous amounts of water experienced by Chinese Cities during severe weather events and ensuring the water doesn’t overwhelm sewers, rivers or wetlands.
Techniques used include storm water ponds, preserving and increasing wetlands, green roofs, porous paving and contiguous open green spaces.
China is in a race to beat the warming planet. As the urbanization of China continues more and more of the country is being paved, leaving less surface area to absorb, divert and control run off. China has declared that by 2030, it wants Sponge City principles built into all urban development plans and has designated 30 pilot cities to fully implement the ideas in the strategy.
Up until this summer, China figured they had a success story on their hands. The city of Wuhan is known as the city of 100 lakes. However almost all of those lakes have been paved over or covered in some way. Over 38 square kilometers of the city have been retrofitted using sponge city techniques, including Nanganqu park. Formerly a drainage ditch from a steel company, the park has been rebuilt as a natural space with permeable paving, swales, drainage ponds and wetlands, all with the goal of absorbing rain and run off.
The program proved it’s worth when a typhoon hit the city in May. Sadly, there was some loss of life and injury, but there was no significant flooding.
This summer, however, revealed that even sponge cities can be overwhelmed by the worst of what the climate is brining. The city of Zhengzhou was inundated by torrential rain, and experienced severe flooding. Critics are saying the $12 billion that China has set aside for their Sponge Cities program is now insufficient, and the strategy needs to shift from handling the regular heavy rains China is used to experiencing, to previously unexpected extreme weather events exacerbated by China’s love of paving.
Elsewhere, cities are in a race against time to battle an atmosphere that can now hold much more moisture and then drop it all at the same time.
The Room for the River program in the Netherlands is a bold strategy, even for a country that knows what it’s like to be underwater.
The program is an effort to manage flooding along the Rhine, Meuse, Waal and IJssel river deltas, and involves widening the green areas around each river, adding a 1300 acre floodplain, and deepening the rivers at strategic points so they can handle more water, as well as allowing them to overflow their banks with minimal damage to people and property.
The project was budgeted at a cool 2.2 billion euros, and was largely successful at preventing the kind of devastation experienced in July of this year in countries upstream from the Netherlands such as Belgium and Germany.
Despite setbacks in China, projects both there and in the Netherlands prove that working with the landscape and anticipating where the water will naturally go to accommodate it, are proving to be far more effective than traditional water management techniques such as dams and dikes.
What remains to be seen is if other governments around the world take notice, and if they choose to pay the high price up front, knowing that the investments prevent even more expensive repairs and restoration after the floods inevitably come.
Beautiful and Functional Infrastructure
Mark Bessoudo had a piece in The Possible not too long ago about urban infrastructure that can be both beautiful and multifunctional. Whether it’s the power plant in Copenhagen that also doubles as a year-round ski run, or the new wetland at Sherbourne Commons in Toronto, smart cities (as opposed to Smart Cities) are figuring out how to make infrastructure that serves more than one purpose, and beautifies as well.
It’s an interesting idea that has come full circle. Infrastructure during the early part of the last century was almost always built with aesthetics in mind. The beauty of a powerplant or water pumping station was a way of telling the world that a city had arrived, and was capable of greatness. It’s nice to see this idea gaining traction again.
Indigenous Reconciliation and Affordable Housing
On the heels of Canada’s first ever National Day of Recognition for the horrors of the residential school system, a fascinating announcement from the Squamish First Nation in the Vancouver area. It seems that due to the nature of their treaty with Canada, the zoning requirements imposed by the surrounding Vancouver municipalities do not apply to them.
They are also experiencing (as is the rest of Vancouver) a crisis of inadequate housing among the members of their nation.
Solution? Built enough housing to solve the problem and ignore the howls of the NIMBYs all around.
It’s elegant in it’s simplicity, and with over 87% of the nation voting in favour of the development, looks like it’s going to go ahead.
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