The torrential rain caused by the city and the loss of life and property caused more and more people's attention. The way people travel today has changed. In the past, riding a bicycle to go out, not afraid of the rain, encountering stagnant water, bypassing or picking up a bicycle passed. Nowadays, many people drive cars, cars can't go home without flames, and they cause urban congestion. It is no wonder that the public and the media are becoming more and more sensitive to the phenomenon of "Jian Shui Tan" in the city. Learn to know that the current drainage technology in China is already lagging behind, and the urban drainage system is a basic gap...

China's drainage design standards are very low:

The French writer Hugo wrote in the novel "The Tragic World" that "The sewer is the conscience of the city." In this year's torrential rains, the "conscience" of many cities in China has been tortured.

Starting from around 10 a.m. yesterday, heavy rain hit the entire city of Beijing. As of 11 o'clock last night, the average rainfall in Beijing's urban areas reached 196 millimeters, far exceeding the 72 millimeters of the "6.23" heavy rain last year. The largest point of the rainfall was 366 mm in the Fangshan District. The Beijing Meteorological Bureau stated that this was Beijing’s record of meteorological observations since 1951, the largest annual precipitation in 61 years. For this reason, Beijing released yesterday the first storm orange warning signal in history.

According to statistics, yesterday's heavy rainfall and strong winds caused the killing of 37 people in the urban area of ​​Beijing, 25 of whom drowned. As traffic is almost paralyzed, many people rushing home have to choose to walk. Some netizens sent micro-blogs and expressed their willingness to open the door so that people who could not go home temporarily avoided or used them. In this terrible weather, the love that netizens sent made them feel slightly warm in the trapped people who couldn’t get home in the rain.

In other large cities, the situation is similar. Drainage design standards in cities in China are very low. Urban arterial roads are basically based on the “annual one-time” rainfall standard, and some places are less than “one year”. This is determined by the original design concept. In the early days of the construction of New China, the economy was poor and the economy was poor. Many of the Soviet Union's design concepts and technical theories were used. The design method was the ultimate strength method (reasoning formula method). “Efforts to save money, the more The better the province, only to meet the needs of the time on the line." Europe and the United States, as developed countries of old capitalism, place greater emphasis on safety and long-term development, adopting more scientific and relatively high design standards. Therefore, the small drainage pipes that were built in China at that time were first designed according to the once-a-month rainfall standard (even 0.25 years and 0.33 years). The design plan allows the accumulation of stagnant water, so the city floods several times a year. It is normal. The "return period" of China's rainwater pipeline design (the "recurrence period" is the concept of hydrology, ie, the design of rainwater pipelines is based on how many years of torrential rain flow is met - editor's note). The standards are lower than those of European and American countries, according to the national " "Outdoor Drainage Design Code", the return period is generally 0.5 to 3 years, the important roads, important areas or short-term water accumulation that can cause more serious consequences, generally choose 3 to 5 years.

The minimum limit for Europe, the United States, Japan, etc. is usually 5 or 10 years. Some developed countries allow local cities to set their own standards based on demand, but they are not allowed to fall below national standards, while our country has only one national standard. And in the implementation process, most cities adopt the lower limit of the standard specification. With the economic development, Chinese cities are rapidly expanding. The old drainage network has long been overwhelmed. In the construction process of each city, there are many phenomena of “emphasizing ground and light underground”. The underground drainage pipeline is a concealed project and does not go to the top. “It is not easy to notice at ordinary times. There is very little concern during construction.” When it encounters heavy rain, it has become a disaster and it has attracted the attention of the public and the media.

"Drainage technology is 30 years behind developed countries":

The design method of our country's drainage system is relatively backward, and the designer's knowledge needs to be updated. In the European Union, the United States, and Canada, design methods have been updated more than a decade ago. In China, the calculation method of rainwater flow still uses the 19th century reasoning formula method. Although the flow reasoning formula method is simple but inaccurate, foreign models have been used to measure the flow rate two or three decades ago.

“If we use computer model calculations, such as the heavy rain in Beijing on July 21, which places there is a lot of water and how much water we need to drain, we can use computer simulations. Now we can only rely on experience. ."

In recent years, the country has invested a lot of funds to support environmental governance, and many talents have also joined the field. Drainage pipe network due to lack of attention, lack of funds, resulting in a large number of brain drain, leaving only a few who stick to the position.

In the prevention and control of urban internal disasters, China has been unable to rely on it. Only the "Flood Prevention Law" promulgated in 1997 and the "Water Pollution Control Law" amended in 2008 are on the edge. In various departments, there are often cases of wrangling and shirking. As a result, the city's internal affairs have received attention every year, but they have not been resolved.

The city drainage system is blind:

Multinational "deep hole" engage in underground water storage

The key factor in the formation of guilt in cities in our country is the lack of standards for urban drainage. China only has flood control systems and drainage systems, and urban drainage systems and standards are still blind spots. "For example, the water conservancy department has 72 hours of draining standards. This is a farmland standard. Farmland will drain water for 72 hours and crops will not die. But if you flood the city for 72 hours, the city will not move and it will die. Our technical normative system has not yet covered this one. The rivers and rivers have been breached by people; the next light rain has caused the water to be drained in time, and there are others who have been in charge of it; but the water has accumulated guilt, but there is no one to control.

In order to fundamentally solve the problem within the city, we must first develop a standard for internal disasters, and then use relevant engineering measures to achieve the goal of eliminating pollution.

Cities in developed countries have two sets of systems. One set is a small drainage system, which is equivalent to the drainage system of rainwater pipelines in China. The other is a large drainage system, which refers to the use of engineering measures and non-engineering measures to solve urban local short-term The drainage problem of heavy rain (above the design discharge capacity of the rainwater pipe network, but not exceeding the maximum load of the urban flood control system) consists of urban rivers, lakes, water surfaces, roads, and regulating structures. This large drainage system is exactly what Zhou Yuwen described as a drainage system.

At present, there are many precedents for the city's drainage system available for reference:

Chicago, USA, has a sewer system that is as glamorous as its skyscrapers. It took 30 years to complete the first phase of the project: Under the drainage system, a 175-km-long, 30-meter deep tunnel with a maximum diameter of more than 10 meters was built.

In London, England, a large reservoir was built over a depth of more than 50 meters below the water supply pipeline.

The drainage pipeline in Singapore is 30 to 40 meters below the subway. Japan also built underground water storage facilities. All developed countries are "deepening their holes" and developing deep space to ensure that the infrastructure is strong enough. This is worth learning and learning from.

Using the extra capacity of the subway industry, “the machines that dig underground will pick up these things under the ground, and then pick them up, for example, they can finish the subway in 10 years, and then they can use these water holes for 10 years.”

Without urban infrastructure, there will be no healthy development of the city. Drainage pipelines are one of the lifelines of the city. It is necessary to change the concept first, plan the system design, and leave something for future generations.

With the development of the city, the original system that supported the city has been unable to move, and it urgently needs new ideas to support it.

Chicago will spend several decades investing 30 billion U.S. dollars in building tunnels and only completing the first phase of the project.

“The sewers in Paris, France (built in the middle of the 19th century) and the sewers in London, England (completed in 1865) are still working well underground.

The sewers in Songzhou, Jiangxi Province, which were built in the Song Dynasty in China, have been for many years. Nowadays, future generations still enjoy the things left by their ancestors. ”

Facing the urban interior, few drainage engineers feel guilty. "What is the reason? What do you do for this job? You have to set the standard for the government. If the return period is a standard once in a year, I'll design it according to one year. The rain that exceeds the design criteria comes and it doesn't matter to me. Who is in a hurry? No one is in a hurry.

The "Regulations on Urban Drainage and Sewage Disposal" currently formulated by the Ministry of Housing and Urban-Rural Development and the Ministry of Environmental Protection is about to be issued. The regulation will regulate urban drainage and sewage treatment, increase financial investment in the construction of drainage and sewage treatment facilities, and specify measures to prevent and control internal disasters. This regulation has brought about the dawn of the construction of urban drainage networks and prevention and control of internal pollution in China.