Last night we had a downpour in Sydney. Flash flooding, streets closed, a certain amount of chaos on the roads. We are told that the intensity of these downpours will increase (due to you-know-what) so some people have started to think about what that will mean for our cities in the future. They have come up with the concept of the sponge city.
The problem is that traditionally we have built gutters, storm water channels and drainage pipes to take the surplus water away but there is a fixed amount of water that these drainage systems will take. The pipes can’t expand, the gutters can’t miraculously balloon when the heavens open up, and the vast acres of concrete and bitumen prevent the water from soaking into the ground, sending it across the surface to these drainage points that can’t cope.
The solution is to have more permeable membranes in our cities to take up the water, to create a city that acts like a sponge. Shanghai is planning to re-use %70 of its rainwater by building acres of green roofs, artificial wetlands and permeable pavements. And Shanghai is not alone. There are many cities that can see the benefits of re-fitting their drainage systems to reduce water run-off and increase water storage.