An underrated issue
Climate change is not a threat: it is a cataclysm happening now. In parallel, with a process that somehow does not counter it but accelerates it, urbanization is growing faster than ever. What are the results of this combination?
There are many, and they seem inevitable. One of these is the ongoing war that cities and small towns are fighting against the increasingly frequent floods that are taking numerous lives. Urgent situations such as these require lasting solutions, and one of these can be summed up with a name: “sponge city”. What is it about?
This is what we are going to explain in this latest article at Seeders Capital.
To understand what a “sponge city” is, it is important to introduce readers to the so-called, urban regeneration, an important environmental practice to adopt in cities which includes the sponge city.
Urban regeneration is to be considered as a system of interventions aimed at renewing an urban space at the level of infrastructures, buildings, and services, and thus redeveloping the fabric of the city also at the level of social cohesion.
When we talk about regeneration, therefore, we are not referring to the simple reconstruction of a single building, or to any project for the redevelopment of the neighborhood. The goal starts from further away and embraces the idea of giving cities a more sustainable dimension, on a human scale.
This important practice of urban regeneration has been implemented by Seeders Capital thanks to many different strategies like Healthy Buildings and Clean Energy Zones.
Resilient urban areas
The sponge city strategy is able to create resilient and efficient urban areas and has already been tested in China.
It is an indispensable approach when excessive urbanization creates megacities that “cancel” the power of the soil to absorb liquids. For this reason, China decided to invest in the construction of 30 sponge cities, with characteristics capable of guaranteeing the resilience of all urban structures to atmospheric events, mitigating the risks of flooding.
But how is it possible to create such resilient urban areas? With a combination of drainage materials, natural parks, underground tunnels and catchment basins.
That’s why the concept of the sponge city seems to have been conceived for the first time by the Chinese government which, following a series of floods that have brought several urban centers to their knees, has chosen to invest in a maxi project aimed at a greater resilience, focusing above all on the implementation of waterproof surfaces and green infrastructures.
For example, the new urban agglomeration that is being built in the Pudong area, 65 kilometers from Shanghai, called Lingang New City, has all the characteristics of the innovative sponge-city model. Roofs are covered with vegetation, wetlands for capturing rainwater, permeable pavements and a large lake in the center. The Chinese government has invested $ 119 million to implement a series of innovative solutions that should serve as a test for possible replication in other cities on the continent.
A strategy that works
A small example (unfortunately always due to negative circumstances) is striking in the city of Wuhan, which was hit by a giant flood in 2016, is now a good candidate to become a “sponge city”. One of its main parks, Xinyu Xie Park, has been transformed into a space with rain storage facilities. Another example: the city of Zhengzhou spent the equivalent of over 80 million euros to build a 5,162 km (3,207 miles) drainage network. The result? 125 critical points where flooding always occurred were removed in the city.
Other memorable and practical examples of the efficiency of these proposals, can be found in Shanghai and Melbourne, which are putting in place some elements of the sponge city against flooding, to make the urban fabric more resilient and to allocate the absorbed water to new uses, generating considerable savings. The London’s Great Outdoors project was also launched in London, which involves the construction of 100 new mini parks located in 26 districts of the city: in addition to increasing their resilience, they absorb considerable quantities of carbon dioxide, purifying the air and decreasing the flow of water in the sewers from the manholes, avoiding roadblocks in the wettest periods.
In particular in Copenhagen, is particularly prone to violent storms and a rise in sea level. In recent years, especially after the storm that caused more than a billion dollars in damage to the city in 2011, investments have begun in a series of climate change-proof projects.
In several districts of the Danish capital, solutions are being tested that mainly involve the construction of water collection basins, in addition to the increase of green areas. In the San Kjeld district, the asphalt has been replaced with a turf, which has been arranged in a hilly pattern. In this way, in the event of further storms or floods, the many green parks in the neighborhood will be able to transform automatically and without damage into as many water basins. An innovative piping system will contribute to the controlled flow of rainwater, capable of channeling rainwater along the roads and then towards the port, minimizing any damage.
In another area of the city, a 22 thousand square meter project was approved, which focuses primarily on greenery, with the transformation of the large urban park into a rainwater collection basin with a maximum capacity of 18 thousand cubic meters of water. The excess water will be guided to a nearby artificial waterway to be filtered, purified and then reused. The same concept is applied to all the streets of the neighborhood thanks to water collection and filtering systems placed between the sidewalk and the roadway.