Abstract: For a long time, the British government has been taking legislative measures to indirectly promote the popularization of household rainwater recovery systems through the “House Construction Management Regulations” and other legal regulations. At the same time, the British government also attaches great importance to the effectiveness of the rainwater recycling system in improving urban drainage capacity and coping with sudden heavy rainfall.
Sponge cities are being built across China. Sponge city takes “slow discharge and slow release” and “source decentralized” control as the main planning and construction concepts. It pursues harmony between urban people and water, which has become an important choice for urban construction in various countries.
Let’s see how developed countries build sponge cities!
The United Kingdom
Start from the source; serve two purposes with one stone
In order to solve the increasingly serious problem of water shortage and improve the municipal drainage capacity of large cities such as London, the British government actively encourages the installation of rainwater harvesting and utilization systems in residents’ homes, communities and commercial buildings. In this way, it solves the above two problems at the root.
The latest data from the British Rainwater Reuse Management Association shows that in recent years, as water prices have continued to rise, more and more households have begun to use rainwater harvesting systems. The cost of a typical house rainwater harvesting system is between £1,500 and £3,000. At present, rainwater harvesting systems for households in the UK are mostly used to meet non-potable water needs such as household irrigation and laundry. Household rainwater collection systems usually have water storage tanks of 1,000 to 7,500 liters installed at home. The rainwater is collected directly from the roof, filtered through aqueducts or a more complex self-cleaning filtration system, and then introduced into underground water storage tanks for storage.
For a long time, the British government has been adopting legislative measures to indirectly promote the popularization of household rainwater recycling systems through laws and regulations such as the 《House Construction Management Regulations》.
While paying attention to household rainwater recycling, the UK is also vigorously promoting the use of rainwater in large municipal buildings and commercial buildings.
The most typical example is the London Olympic Park. The main building and woodland in the park have established a complete rainwater collection system during the construction process. The 225-hectare park is irrigated entirely with rainwater and treated gray water through recycling of rainwater and reuse of wastewater.
At the same time, the British government also attaches great importance to the effectiveness of the rainwater recycling system in improving urban drainage capacity and coping with sudden heavy rainfall.
According to data from the British Rainwater Utilization Management Association, the current household rainwater collection system can increase the ability of a single household to cope with sudden rainfall to the level of once a year. At the same time, after large-scale facilities and communities establish their own scale rainwater harvesting systems, the community’s ability to deal with sudden rainfall may increase to the level that occurs once in 30 years. On this basis, the response capacity of the 30 or so large storage lakes established by the water company around the greater London area may increase to once in a century. And the response capacity of the Thames River, the main drainage channel in the Greater London area, will also increase a lot accordingly.
France
Different shapes, improve circulation
France, located at the western end of the European continent, is significantly influenced by the oceanic climate. There usually is relatively abundant rainfall throughout the year. France, as one of the origins of the prototype of modern cities, has many major cities in its territory with different design ideas for drainage, water logging prevention and rainwater recycling treatment.
As the capital of France, Paris has a water circulation system that can be regarded as a model among metropolises around the world. In 1852, the famous designer Osman reconstructed the water circulation system, which was praised by the French as “the most uncontroversial system” and basically used today. At present, France is gradually implementing the ambitious “Great Paris Transformation Plan” with a planned investment of up to 100 billion Euros. According to the staff of the Paris City Government, in this grand plan, Paris will further improve and maintain the existing urban water circulation system. It will also add water storage and purification treatment centers in various locations in Paris to improve rainwater collection and reuse.
The water cycle treatment of Lyon, another famous French city, is adapted to local conditions and fully utilizes the power of nature. Compared with Paris, Lyon’s urban water cycle does not overemphasize the role of underground drainage pipes. Several community areas in the city have low-lying ground, so the rainwater collection fully makes good use of the features of ground. Then the rainwater can pass through to the designed canals in these low-lying areas. The Central Park in the center of Lyon is built in a low-lying land. When the local architectural designer built the park, a water storage pool with a capacity of 870 cubic meters was deliberately set aside.
Germany
Efficient water collection with ecological balance
In recent years, Germany has begun to widely promote the “swale-infiltration system”, which connects various on-site depressions, infiltration canals and other facilities with drainage pipes with holes. It forms a decentralized rainwater treatment system. Low-lying grass can store infiltrating rainwater for a short period of time, while infiltration canals can store rainwater for a long time, thereby reducing the burden on urban drainage pipes.
Major cities in Germany
There are three ways to use rainwater:
- Roof rainwater storage system
- Rainwater interception and infiltration system
- Rainwater utilization system for ecological community
In addition, they are still exploring other methods: building a huge urban park in the city center; encouraging citizens to participate in the construction of “green roofs”. Experts believe that if the roof greening work can reach a certain density, at least 60% of the rainfall can be retained in the future.
Singapore
Well-guided and strict standards
As a tropical island country with abundant rainfall, Singapore’s maximum annual rainfall has continued to rise in the past 30 years, but urban water logging rarely occurs.
First, pre-plan the urban drainage system. Singapore usually plans and designs the underground and surface drainage system of the building before the construction of the ground building. Therefore, each building, including sidewalks and roads, has a certain number of drainage channels around it.
Secondly, strengthen rainwater drainage and build large storage tanks. The rainwater collected through the urban rainwater collection system will eventually flow into 17 large cisterns around the city of Singapore, and these large cisterns are also the key to solve the problems of rainwater drainage and urban water logging in Singapore.
Third, establish strict ground building drainage standards. The Singapore Public Utilities Board has revised and improved the ground building drainage system standards several times, requiring all new buildings to increase the height of the waterproof threshold.
Great solutions from HOENSOEY Technology
In China, HOENSOEY Technology actively participates in China’s sponge city construction, launching a series of rainwater collection modules and related supporting products for shallow surface water treatment systems. Among them, the latest product HOENSOEY Cells has great pressure bearing ability (up to 130 tons/square meter) and high rate of water storage (95% of the water storage space). In addition, installation is fast and easy (self-contained patent structure buckle). Only shallow excavation is required, which greatly saves manpower and equipment costs. And it makes the construction of sponge cities easier.
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