Wuhan rainstorm waterlogging blame? Pan can not do so

Wuhan heavy rain net friend drainage ditch

fenghuangxinwen· 2016-07-07 04:27:11

in the rainstorm flooded" [lead]

WuHan Railway Station, according to media reports, since June 30th, the Yangtze River and the Huaihe River area, southwest Eastern and other places in the strongest rainfall flood season, causing severe floods in some areas. Hubei, Jiangxi, Hunan, Jiangsu, Guangxi, Guizhou and other provinces hundreds of rivers flood alert level. In addition, Poyang Lake for the first time this year the river water intrusion phenomenon. According to

Chinese national headquarters informed that, as of July 3rd statistics, there are 26 provinces (autonomous regions and municipalities) 1192 counties suffered floods, crops affected area of 2 million 942 thousand hectares, the affected population of 32 million 820 thousand people, emergency transfer of 1 million 480 thousand people, 186 people died, 45 people missing, 56 thousand houses collapsed, the direct economic losses of about 50 billion 600 million yuan.

in Hubei, Wuhan, from June 30th 20:00 to July 6th 10, the Wuhan national basic weather station records has a total rainfall of 560.5 mm, Wuhan has its own breakthrough since meteorological records week persistent precipitation maxima, while still under the rain. Heavy rains caused many flooded roads, a subway because the water closed. The

flood disaster has been described as "a hundred years". In recent years, the "hundred years" frequently appear in newspapers, almost every year, netizens joked, "yesterday I met in this life eighth times a hundred year storm". Why is the hundred years of the disaster, for everyone, is a homely food?

aerial Wuhan City waterlogging, traffic

for two consecutive years "hundred years" too normal

hundred years, which means only happens once every 100 years the event. But in fact, in hydrology, "hundred years" is this meaning, the correct understanding should be "arbitrary within one year have 1% probability of things". According to friends

Shu Lele's research, "hundred years" is Chinese translation will aggravate the distortion of foreign words for example. The United States from 1960s began using the concept of event 100-year for risk assessment, the purpose is to evaluate the reliability of the project under the one percent probability event". Event 100-year as a calculation parameters, professional call reproduction period, a more reasonable translation should be "1% of the probability of event". But when it is translated into Chinese "Bainianyiyu", it can easily lead to misunderstanding.

hydrology based on the precipitation and peak flow observation survey data, according to the size and grade of rare degree appeared to measure the hydrological phenomenon. For example, the frequency of floods often expressed as a percentage, the smaller the frequency of floods, indicating that there is less chance of a flood of magnitude more than the magnitude. The flood frequency is 1%, compared to 100 year flood.

with the knowledge of probability calculation, although a year occurred in a "once-in-a-century" event probability is 1%, but in one hundred years, this event occurs at least once the probability will rise to 63%. And in every ten years, the probability of occurrence of a "hundred years" event will be greater than 9.5%. These events are called "once in a hundred years". So, a "hundred years" the number of occurrences is relatively frequent. Since

year flood probability is independent, so, for two consecutive years "hundred years" is also very normal, for one hundred consecutive years "once-in-a-century" is possible in theory.

and "Bainianyiyu" is likely to change. Because this probability is based on the observed data. For example, according to the observed data of precipitation, a city of 10mm per hour is hundred years. But if there is such a precipitation for many years, then the statistical data will be updated. The precipitation of 10mm per hour is probably ten years.

in addition, the incidence of "once-in-a-century" events in different regions are independent of each other. That is to say, Beijing has a "event at the same time not occur even in a hundred years", Shanghai may in the event of another "once-in-a-century" event. Therefore, in the news, often see "once-in-a-century" words, most of the time not being exaggerated or lying, but really so.

of the Wuhan University of Technology campus consists of thirteen buildings east hospital dormitory, up to now the water level has reached up to the chair. Students in the water to get up to review the mechanical principle, to prepare for the morning of the exam.

storm culprit El Nino, really is a once-in-a-century

storm continued arch-criminal considered El nino. El Nino is an anomaly in the tropical sea, which is characterized by a significant increase in the sea water in the eastern and central equatorial Pacific Ocean. When the eastern sea area of the equatorial Pacific sea surface temperature is higher than the same period the year at 0.5, and continued for more than 3 months, entered the "El Nino"; lasting more than 6 months, is recognized as a "El Nino event". When El Nino events occur, due to the high temperature of the tropical ocean, through the ocean and atmospheric interactions will change the normal atmospheric circulation, which leads to global climate anomalies. The

began in September 2014 and ended in May 2016, El Nino, life history, total length intensity, peak intensity of three indicators have reached the highest, is the strongest El Nino events since twentieth Century, known as the hundred years a bit too much.

after a hundred years, can be called super El Nino events, only two times, once in the 1982-1983, once in 1997-1998, all lasted about 1 years, and this lasted 21 months.

El Nino event, has a significant impact on the world. 2014, 2015, the global temperature surface temperatures even a new high, in January 2016, the Arctic temperatures recorded second times in the winter rose to zero degrees celsius. South Africa, Brazil and other places continued drought, Indonesia, Philippines, Australia and other frequent forest fires, India Peninsula, Latin America, there are more rain and floods.

on China, El Nino events in the northern winter prone to mild winter, in the summer of second the Yangtze River and southern regions prone to floods, prone to cold summer in the Northeast china. Coupled with the South China Sea Summer Monsoon in late May, so that the more precipitation.

at least at the beginning of this year, the National Climate Center predicted that this summer, the south, especially in the middle and lower reaches of the Yangtze River precipitation may be too much, prone to flooding. Since the flood season this year, heavy rainfall in southern area frequently, more precipitation and strong. The Yangtze River Basin Rainfall and rainstorm days are the same period of history since 1961; precipitation in Songhua River basin for the same period in history, more than and 2, Liaohe basin average rainfall for the same period in history, more than and 5, and more than two watershed mean torrential rain days are 1961 to the same period in the history of the more than and 2.

7 5 July, Hunan Heshan District of Yiyang City Quan Jiao Town, hydropower has been broken, the street has become a world of waters.

Wuhan waterlogging blame a once-in-a-century storm? This pot can't throw

almost every rain and flood "in Wuhan, the flooded, the most important is the most direct reason is that mentioned above, the heavy rainfall after the El Nino event. Behind the climate change in recent years, the world continues to appear extreme weather events. Over the past 20 years, the southern region of China was affected by extreme weather events, floods and floods, and the frequency of the frequency has increased significantly.

but in addition to natural disasters, the waterlogging in Wuhan, it is part of the man-made disaster. Waterlogging can be said to be Chinese in the process of rapid urbanization, the term "first on the underground city construction mode of the consequences.

city scale expansion, the influx of population, the city's temperature is higher than the surrounding, the formation of "heat island effect", rising air is easy to produce relatively strong rainfall, enhances the city rainfall frequency and intensity of city development and construction; large-scale science, which has natural water storage and flood control function, peak depression ponds, lakes and reservoirs have been artificially damaged or fill it with filling, reduce rainwater storage diversion function.

is known as "100 Lake City of Wuhan, in recent years, city development, illegal filling the lake led to the city water system and the lake area is shrinking, the natural absorption and storage system of city rainwater capacity decreased and loss. 1950s Lake area of 1581 square kilometers, the city has 127 lakes, in 80s has been reduced to 874 square kilometers. In the past 30 years, it has reduced by 228.9 square kilometers, and the lake has been reduced to more than and 30. Correspondingly, the total area of Wuhan urban construction area increased year by year, from 455 square kilometers in 2006 to 507 square kilometers in 2011, 5 years, the area increased by 11.53%.

in the past, soil and water can save a lot of water, and now, with the city construction "go faster", a large number of green land, wetland, pond city disappeared, "hard" has become more and more serious, so that one to rain, the rain is difficult since the row, 90% row go to rely on the drainage network. And Wuhan's drainage system is clearly unable to bear this responsibility.

2014 years, the newly revised "outdoor drainage design specifications", urban drainage facilities in the general area of the design storm return period of 1-3 years, an important region for 3-5 years, especially important areas for 10 years. But in fact, most of the cities in China, even in the construction of a young city like Shenzhen, have adopted the Soviet model, because the Soviet Union had less rainfall and the standard of the drainage pipeline was low. Most of the city generally adopt minimum standards, which is also a year. As a comparison, the developed countries and regions, urban drainage pipe network standards, the United States drainage standards for residential areas 2-15 years, generally take 10 years, commercial and high-value areas for 10-100 years, while the UK is 30 years.

Wuhan, some of the pipe network is even built in the Qing Dynasty, drainage capacity degradation is serious. Wuhan City Water Department has said that the daily rainfall or hourly rainfall exceeded the "one-year" standard, in Wuhan every year to 7 - 8 times average.

three years ago, the Wuhan Water Bureau through the "action plan" to tackle the construction of drainage facilities in Wuhan city for three years, 13 billion yuan investment, improve the city drainage system, known as the confidence after three years Wuhan will bid farewell to "see the sea". At the time of the media claimed that the three year plan is completed, will be able to withstand 200 mm /24 hours, 50 mm /1 hours of heavy rain. Such rainfall in Wuhan in the history of an average of 10 years will be a "," one of the 15 East Lake are not afraid".

the Wuhan waterlogging, can not be said of the 13 billion boondoggle, in fact the Wuhan University area waterlogging situation is not so serious. However, even billions of drainage project fully implemented, can only meet the "ten years" flood disaster, with such plans and standards to deal with the disaster of a real "Bainianyiyu" El Nino, "too difficult".

1998 flood rescue soldiers. Like the rain, floods in 1998 were also affected by the El Nino events. But unlike in 1998, this year over North and South swing, the longest duration of the rainstorm process is better than the same period in 1998.

a "hundred years" can not explain how frequent extreme weather city lazy political climate change caused by

, all the city managers need to pay attention to the problem. In the construction of drainage system, many cities at home and abroad have the significance of reference. Saitama Prefecture,

is often flooded, in 2006 completed the 50 meters deep underground drainage system, drainage system is the world's most advanced, concentrated after water storage rate of 200 tons per second and then discharged to the nearby Edo sichuan. The system can prevent the typhoon season due to heavy rain and possible flooding, guarding the Tokyo area of Japan to avoid flooding. In addition, in the underground tunnel across the Tokyo downtown lot, these underground tunnel can hold 540 thousand tons of water, such as the Tokyo underground drainage system has a total of 23, the storm invasion could complete the normal function. Drainage system

Paris are in the 50 meters below ground, and took 126 years to complete the construction, with a total length of 2347 kilometers, equivalent to Paris to Islam but Boolean distance. According to the size of the channel can be divided into small sewers, drains and sewers in three; every 12 billion cubic metres of water through the discharge. The sewers of Paris like a river navigable, day and night lights, there are 100 thousand visitors each year, sewer Museum has become a famous tourist attractions.

even the drainage system of our ancestors, is now the vast majority of the city. The second largest city in Jiangxi province of Ganzhou in the Song Dynasty established a set of advanced drainage systems, Fushou ditch. Before the Song Dynasty, the city of Ganzhou is also suffering from the flood year. The Northern Song Dynasty Xining years, an official called Liu Yi planning and construction of the Ganzhou city streets, according to the layout of the streets and terrain features, take the district drainage principle, built a two road drainage system. The natural flow of longevity ditch, the city's natural rainwater and sewage discharged into the river, the water window channel slope is 4.25%, is 4 times the normal sewer by slope. This ensures that the formation of strong currents, enough to take sediment into the river. This set of drainage system is still in use, to ensure that Ganzhou's Millennium is not a flood". In the surrounding Guangzhou, Nanning, Nanchang and many other cities suffered flooding, Ganzhou is still safe and sound.

mentioned above, due to climate change, the former "once-in-a-century" disasters are more and more common, a "once-in-a-century" standard will need to be modified. But a lot of city in the process of construction, confined to the immediate interests, only focus on the ground rather than underground, ignoring the problems of drainage network exists, whenever I encounter a disaster, with all the "once-in-a-century" excuse people, sooner or later this pot is throw off.

Tokyo underground drainage system was built in 2006, is strong and advanced, a series of concrete vertical pit, underground river 60 meters deep.

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