In March 2013, a female college student was caught in a sewer due to a heavy rain.
and many more. . . . .
What causes urban flooding?
Most of us have only seen the wealth of big cities, but have not noticed the crisis that lies underground. The current situation in our country is that the construction of the above-ground cities is advancing rapidly, but the underground pipeline network is left unattended, and after the accumulation of time, the problem becomes more serious and the management becomes more difficult.
In the case of urban waterlogging, some people habitually attribute it to natural disasters and man-made disasters. Many local governments have also seized this point and expanded it. The media also followed the report, but concealed the real cause of urban waterlogging. Furthermore, it makes the public think that the cause of urban waterlogging is natural disaster. So is this really the case?
Natural disasters that cause urban flooding:
Reason 1: Urban sponge reduction
In the past, there were many wetlands such as mud, lakes, grasslands, fish ponds, farmland, etc. These wetlands now seem to be the "sponge bodies" in the sponge cities we have been launching. With the expansion of the city, sponge bodies such as green space and ponds have been reduced, and hardened roads have increased. Drainage can only be achieved by relying on urban drainage pipe networks. The water seepage speed and water holding capacity are not as good as before.
Reason two: Urban rivers are flooding
City construction likes to lay out along the banks of the river, so it looks more beautiful, but the disadvantage of the back is: if there is heavy rain, water will accumulate in the upstream of the river, and the downstream will also show a rise in water level, which will cause the water level of the urban underground pipe network to rise High, showing a blocking phenomenon.
Cause three: The urban heat island effect is enhanced
With the rapid development of cities, the dust in the city, the exhaust of cars increased, the severity of the heat island effect became more severe, and then the rain island effect was formed. The greater the sky above the big city, the greater the rainfall. Rainfall in the sky has increased, and the ability to penetrate the ground has decreased. The city's drainage pipe network has not yet had an effect, and then constitutes a waterlog.
Human disasters that cause urban flooding:
Cause one: Inadequate maintenance of urban sewer pipe network
The sewer network in most cities is narrow and severely blocked, which is caused by lack of maintenance for a long time. The city sewers are built in seven points and maintained in three because maintenance is very important.
Reason two: Urban construction planning is unreasonable
Unreasonable land occupation is serious. For example, in order to expand the city, the high-permeability areas have been built into the high-rise buildings, the city's inland rivers have been filled and so on.
Cause three: Unqualified urban drainage regulations
Cause four: Urban underground drainage network management is difficult
It touches part of the complexity: municipal administration, water conservancy, urban planning, garden construction, and many other parts. At this time, a strong part is needed to harmonize.
Reason 5: Expensive construction of underground pipeline network
There are hundreds of millions of dollars in one kilometer, which requires long-term and huge fiscal budgets.
Reason 6: The construction of the underground pipeline network will not show any effect in the short term
Because of the underground construction, it is difficult to pay attention to it, and if there is no heavy rain in the short term. The effect of the underground pipe network is difficult to exert.
International Urban Waterlogging Management Measures:
Paris: 50 meters underground in Paris, it has the world's most prosperous underground pipeline system. It took 126 years before and after the Parisians to complete the construction. The water channels are staggered and dense like spider webs. They are also extremely spacious together.
The sewers in Paris serve as attractions, receiving more than 100,000 visitors each year, and the Paris has a museum of underground waterways
Japan: At the end of the 1950s, Japan's economic development was similar to that of China. It entered a period of rapid economic development. However, due to the backwardness of the sewer system, it suffered from urban flooding. Tokyo, Japan, floods Jinshan with rainstorms and watches the sea at home.
In 1964, Japan established a special underground pipe network comprehensive management part to unify the construction and drainage specifications of sewers, replace the aging pipelines, substantially revised the "Sewer Law", and legislate to regulate urban sewers. A huge budget is invested each year. Tokyo's sewer drainage specifications are once in 5-10 years, and the widest sewer can reach 12 meters.
The current feasible urban flood management methods:
According to the "Sponge City Construction Skills Guide" issued by the Ministry of Housing and Urban-Rural Development of China, it is pointed out that the key to building a sponge city is to continuously improve the planning and quality of the "sponge". If conditions permit, a new "sponge body" must be built. At present, some natural wetlands in the city must be vigorously protected, but the management of urban waterlogging depends on natural wetlands. Some sponge bodies are needed. These sponge bodies include infrastructure such as permeable bricks and rainwater collection systems, and permeable bricks. It has very good water seepage and water retention effects. The rainwater collection system has water storage and purification effects. The two are used scientifically and reasonably. It will be very useful to reduce the pressure on urban municipal pipelines.
To sum up: In today's highly prosperous age of science and technology, to test whether a city is prosperous or not, you can know the answer with a heavy rain.
Therefore, facing the problem of urban waterlogging, General Secretary Xi Jinping proposed to build a modern sponge city. In October 2014, the Ministry of Housing and Urban-Rural Development of China issued the "Sponge City Construction Skills Guide". A sponge city means that the city can be like a sponge. It has outstanding “elasticity” in adapting to environmental changes and responding to natural disasters. This is also a powerful countermeasure that China has taken to deal with urban flooding.