New survey published today by Arup has found that the urban centre of London is the least “sponge-like”, or naturally able to absorb rainwater, of seven major global cities. London emerges with a “sponge” rating of just 22% – far behind Auckland, which ranks top with 35%.
Arup’s first-of-its-kind Global Sponge Cities Snapshot aims to prompt cities to ask: how spongy am I? Authors of the survey are calling on city leaders to move beyond concrete interventions and instead look to nature for solutions to climate-related challenges, such as managing heavy rainfall.
Authors studied a sample of approximately 150km2 in seven diverse global cities – Auckland, London, Mumbai, Nairobi, New York, Shanghai and Singapore – to assess how well their existing natural infrastructure helps them absorb rainfall.
The new analysis comes as the IPCC predicts that water-related risks will increase with every degree of global warming, with around 700 million people currently living in regions where maximum daily rainfall has increased.
In Auckland, half of the area studied was made up of green and blue spaces, which helped it achieve its high “sponge” rating. The only city snapshot to contain a greater proportion of green and blue spaces is Nairobi (52%), however Auckland’s more permeable soil helped to give it a narrowly higher overall “sponginess”.
By comparison, London and Shanghai align much more with the “concrete jungle” stereotype, with a higher percentage of hard surface in their urban centres: 69% and 67% respectively. This places them as the two least “spongy” of the cities surveyed.