Every single year, mostly in rainy seasons, some big cities suffer due to floods. Fortunately, the sponge city concept has become a great solution to avoid floods and other natural impacts. Poor people are the most beneficiated! See how the sponge city concept works!
Sponge City, an idea that saves!
The sponge city concept is kind of an old one. Amazingly, only nowadays public services brought up the idea.
Sponge city is the result of an urban project that aims to keep the rainwater just where it falls, due to the natural permeability of the terrain.
In other words, during heavy precipitations, water is absorbed by soil and vegetation altogether.
Floods and other tragedies that are apparently "nature fault" are actually the result of human omission that relegates their obligations to their community and the environment in the background.
Thus, the sponge city program's focus is to retain rainwater by waterproofing the paved floor so that part of it evaporates and the rest is gradually drained. Thus, instead of a sudden flow straight into the rivers, the water is retained before.
Rapid runoff causes all kinds of urban dirt to be dragged by the water that runs on the surface.
Natural agents such as pollen and flower buds - falling from the city's trees - flow into lakes and rivers and can kill fish due to nutrient overload and water oxygen depletion.
Because of the excessive number of floods, China's first sponge city is Wuhan. Since the place is known as "the city of hundreds of lakes", it was chosen for the pilot project.
The other reason to choose Wuhan is that it's located near the junction of the Yangtze and Han rivers, being subject to frequent floods, especially in the summer monsoons months.
After Wuhan, 16 other Chinese cities were also included in the sponge city program. These cities would also have new drainage systems and more green areas.
Sidewalks and streets waterproof + soil water absorption = end of floods!
The results are visible!
According to the Director of Water Management of the Chinese government, Wen Mei Dubbelaar, "In a natural environment, most precipitations infiltrate the terrain, draining well and avoiding flooding. This phenomenon does not happen in paved places, because they do not drain water, generating flooding. In the sponge city, only 20 to 30% of rainwater is absorbed by soil, reducing the risk of flooding. The wider streets of Lingang already have permeable paving and rainwater flows without accumulating!"
Expected results to sponge cities:
20% of the urban areas of sponge cities will be able to absorb and store 70% of rainwater.
170 km2 out of a total of 860 km2 of the urban areas will receive water drainage systems and green spaces.
More trees planted and new awnings placed on sidewalks, to increase shade.
Buildings painted with light colors in order to reflect more heat, instead of absorbing.
Roofs of buildings and houses, covered with grass, for greater absorption of water and later release it through evaporation.
Waterproofing the paving of warmer areas of the city and roads, to prevent the overheating of streets and asphalt, on very hot days.
The sponge city became one of the most spectacular urbanistic programs worldwide!
Requirements to be a sponge city project:
- Reformulation of the road system (roads and streets)
- More tree planting and creating shelters for the protection of inhabitants in rainy times
- Construction of smart buildings adapted to the standards of the city-sponge concept
- One-off campaigns, face-to-face or virtual courses, seminars and training, focused on new concepts
- Agreements with other sponge cities, for exchange of services and information
- Integration into the principles of slow movement and other environmental education movements for the awareness of the local population
Ultimately, new urban laws have to be urgently created in order to rule the water collection, storage, and water treatment infrastructure systems of those cities where every single year has tragedies due to floods!