The ecological urban planner Kongjian Yu believes that the urban model of gray cities, which prioritizes the use of cars and expels water from the basin, can be transformed into sponge cities . This is achieved by removing concrete, creating green areas, collecting rainwater and the impulse of traditional agriculture in cities. It is an initiative that has developed in hundreds of projects in 250 cities in China and can be applied in Mexico.
In an interview with La Jornada , the expert, president of the School of Architecture and Urban Design at the University of Beijing and who has developed regional ecological infrastructure solutions, believes that in Mexico the same thing happens in other countries: water is extracted, use, never infiltrate, is ejected from the basin. With this the aquifer loses its balance, the city sinks.
Given this, he says, sponge cities are a low cost solution, based on nature. He explains that the model is based on the vision of the basin, in which cities are located, and the solution is based on the restoration of the river system at regional level. Each piece of the city, whether roof, garden or terrace, can serve as a sponge. This allows the aquifers to be recharged and the sinking of cities reduced, he says.
He mentions that, for example, in the conservation areas of the city, water can be recharged in any hole that is drilled. In cities, houses can become collectors and the balance is maintained, it accumulates in the rainy season and helps in the dry season .
The model is not expensive
In relation to contaminated water, which contains many nutrients and goes to drainage, it can be filtered with techniques that nature provides. Residual liquids are removed solids, pass through systems of aquatic and native plants to generate clean liquid.
He asserts that this model is not expensive, because it is to use agriculture and traditional methods in the city. He points out that there are three objectives, the regulation of water use; clean it and make it productive, instead of sending it to the drain, which is very expensive. And finally it infiltrates the aquifer. It is about recomposing the hydrological cycle and helps adaptation to climate change, it is precise.
He recognizes that among the difficulties in establishing the model are convincing politicians, mayors, the president and, above all, engineers. He points out that engineering has 300 years of existence, it is based on the industrial revolution. It's over. We need a new system and a new revolution. A new code system. We have to remove the concrete .
Kongjian Yu summarizes: sponge cities are based on people, clean water and produce food . The expert will give a keynote speech today at the Faculty of Architecture of the UNAM. In the following days he will tour Mexico City and meet with federal authorities.