What's the important event in August 1975?
Introduction:1from August 4 to August 8, 975, a sudden rainstorm occurred in Zhumadian, Henan Province, and the reservoir burst, killing more than 240,000 people. Become the world's biggest reservoir dam-break tragedy.
In August, more than 60 reservoirs in Zhumadian, Henan Province, covering an area of 10000 square kilometers, broke their dams one after another, and nearly 6 billion cubic meters of flood water flowed freely. 1.0 1.5 million people were affected, more than 26,000 people died, 5.24 million houses collapsed and 300,000 farm animals were washed away. The Beijing-Guangzhou line running through the north and south of China was washed away102km, stopped for 16 days, affected transportation for 46 days, and caused direct economic losses of nearly 10 billion yuan, making it the largest and most tragic reservoir dam-break tragedy in the world. After 30 years, looking back at this dike-breaking accident, the problems reflected from it are worth pondering. ...
On July 3rd1,0975, Typhoon No.3 formed over the Pacific Ocean. On August 7, the typhoon entered Zhumadian area.
Before the arrival of the typhoon, there was already heavy rain in Zhumadian. From August 4 to 8, the maximum rainfall in the rainstorm center reached 163 1mm, and from August 5 to 7, the maximum rainfall was 1605mm, which was equivalent to 1.8 times of the annual average rainfall in Zhumadian. From 4th to 8th, the rainfall area over 400 mm reached 194 10 square kilometer, and the rainfall area over 1000 mm was concentrated in the area from Banqiao Reservoir and Shimantan Reservoir to Fangcheng in the west of Beijing-Guangzhou Railway. The rainfall intensity of this rainstorm, in the rainstorm center-Zhuang Lin, located in Banqiao Reservoir, the maximum 6-hour rainfall was 830mm, which exceeded the world record at that time-the maximum 24-hour rainfall of 782mm 1060mm in Smith Port, Pennsylvania, USA, and also set the highest record of similar indicators in China.
Witnesses said: within a few days of heavy rain, day is like night; The rainstorm is like an arrow, and there are dead birds everywhere on the mountain after the rain; Take out the washbasin from the room and it will be full in the blink of an eye.
The rainstorm was unexpected by the reservoir designer.
Banqiao Reservoir has a designed maximum storage capacity of 492 million cubic meters and a designed maximum discharge capacity of 1720 cubic meters per second. This flood, the total flood volume is 697 million cubic meters, and the peak flow is 65.438+0.3 million cubic meters per second.
On the morning of August 5th, the water level of Banqiao Reservoir began to rise, reaching the highest water level 117.94m on the 8th. When the breakwater was 0.3m deep, the dam in the main channel burst and the reservoir water of 600 million cubic meters suddenly discharged. According to the records, the maximum instantaneous flow is 7.8 1 10,000 cubic meters per second when the breach occurs, and the downstream flood is 7.05438+10,000 cubic meters within 6 hours. After the dam-break flood enters the river, it rushes downstream at an average speed of 6 meters per second, forming a torrent with a head as high as 5-9 meters and a flow width of 12- 15 kilometers between the dam and the Beijing-Guangzhou railway.
The water of Shimantan Reservoir began to rise at 20: 00 on the 5th, and reached the highest water level11.40m at 0: 30 on the 8th. At that time, the water depth of the breakwater was 0.4m. The total inflow flood was 224 million cubic meters, which was completely discharged in five and a half hours. The maximum dam-break flow is 30,000 cubic meters per second, and the downstream Tiangang Reservoir is breached.
The two flood storage and detention areas, Nihewa and Laowangpo, in the lower reaches of Shahe River and Red River, have a maximum flood storage capacity of 886 million cubic meters. At this time, the flood storage dikes overflowed in many places and lost their control functions.
The main rivers in Zhumadian area have burst their banks and overflowed. The whole area is 300 kilometers long from east to west, with a length of 150 kilometers from north to south, and 6 billion cubic meters of flood surges across Wang Yang. About 654.38 billion cubic meters of flood water flowed into Fenquan River basin because of the breach of the main river embankment in Laowangpo flood detention area on August 8. On the evening of the 9th, the flood entered Fuyang, Anhui Province, and the Quanhe River burst its banks in many places, and Linquan County was flooded.
It is understood that on August 5 17, there was a general rainstorm in the upper reaches of the reservoir, and the accumulated water in the courtyard of Banqiao Reservoir Management Bureau exceeded 1 m, and the telephone in the reservoir area was interrupted. The Administration lost contact with rainfall stations such as Longwangmiao and Taohuadian in the upper reaches of the reservoir.
On August 7th 19: 30 and August 8th at 00: 20, the Reservoir Management Bureau sent two special emergency telegrams to the higher authorities, requesting to blow up the auxiliary spillway by plane to ensure the safety of the dam, but failed to reach the higher authorities. At 8 1: 40, the reservoir management bureau sent a special telegram to the superior for the third time to report the reservoir breach. At 4 o'clock, the local garrison of the reservoir risked being struck by lightning, moved the walkie-talkie antenna to the roof, and informed Zhumadian Military Division of the dam break and reported it to the prefectural party committee. At the same time, the reservoir garrison used signal flares to report the danger to the downstream people and make an emergency transfer, but it failed because there was no prior agreement.
-Sudden floods
227 households and 9,600 people died in Daowencheng Commune. ...
The 50-ton carriage of Suiping Railway Station was washed away for 5 kilometers, and the rails were twisted into twists. ...
In the early morning of the 8 th, the flood rushed out of the Banqiao Reservoir like a runaway wild horse and rushed downstream at a speed of 6 meters per second. Wencheng Commune, which bears the brunt of the disaster, suffered the most, with 227 families killed and 9,600 people killed.
On the morning of 8th 1 hour, after the dam of Banqiao Reservoir broke, only one hour later, the flood rushed into Suiping County, 45km away. Someone was strangled by wires on the way, or rushed into a culvert to suffocate. When the flood crossed the high slope of Beijing-Guangzhou Railway, more people fell into the whirlpool and drowned.
In less than 6 hours, Banqiao Reservoir discharged 71100 million cubic meters of flood water. Suiping county has 830 square kilometers of land and a piece of Wang Yang. After the flood, there were no villages, big or small.
On the land of 65438+100000 square kilometers, nearly 6 billion cubic meters of flood water flowed freely. People who survived the robbery recalled that when the 24.5-meter-high dam of Banqiao Reservoir burst, the flood peak sounded like a landslide, and its shape was like tumbling over the river. Everywhere, buildings and trees disappear instantly. On the mainstream water, people are crowded, struggling desperately and calling for help. The bodies of the victims and pigs, sheep, cows, horses, chickens, ducks and other animals drifted with the water. The stone mill was washed away by the river, and the chain tractor and heavy mechanical lathe rolled with the river. The 50-ton train car of Suiping Railway Station was washed away for 5 kilometers, and the rails were twisted into twists. ...
After the flood, only a gray land was left. In the river ditch, muddy, human and animal bodies, littering, terrible. The villagers of Daluchen Village, 4 kilometers east of Banqiao Reservoir, later described it as follows: "It is white from a distance and empty from a distance. There is no road into the village, only one tree is left. "
According to statistics, in this rainstorm, two large reservoirs, Banqiao and Shimantan in Zhumadian, Henan Province, two medium-sized reservoirs, Zhugou and Tiangang, and 58 small reservoirs broke their dams within a few hours. In 30 counties and cities in Henan Province,178,000 mu of farmland was flooded,10150,000 people were affected, more than 26,000 people died, 5.24 million houses collapsed, 300,000 farm animals were washed away, and the Beijing-Guangzhou line running through the north and south of China was washed away 102 km, and traffic was interrupted.
-"No.7503" typhoon moved to Henan.
● The reservoir burst due to a rare rainstorm in history.
According to meteorological data, on August 4th, 1975, Typhoon No.3 in China ("Typhoon No.7503") crossed the island of Taiwan Province Province and landed in Jinjiang, Fujian. At this time, just as the air near Australia in the southern hemisphere broke out in the northern hemisphere, the tropical convergence line of the western Pacific jumped northward, causing the landing typhoon not to disappear quickly on land as usual, but to cross Jiangxi, Hunan, Changde and the Yangtze River with rare intensity and suddenly reach the hinterland of the Central Plains.
On August 5, the mysterious typhoon 7503 suddenly disappeared from the radar monitoring screen of Beijing Central Meteorological Observatory. Due to the adjustment of the westerly belt in the northern hemisphere, Typhoon No.7503 could not turn eastward on its way northward, so "stop and move less in Henan" led to the disaster.
The specific area of "stagnation" is in the big arc zone between Funiu Mountain Range and Tongbai Mountain Range, where there are a large number of horseshoe-shaped valleys surrounded by mountains on three sides and canyons sandwiched between the two mountains. The violent vertical movement of southerly airflow here, coupled with the participation of other weather scale systems, caused a rare torrential rain in history, which was also an important reason for the reservoir breach.
According to the reporter's understanding, the forecaster of the Central Meteorological Observatory only drew the rainfall of 100 mm in this area at that time, because there was no scientific understanding at that time, and it was impossible to draw a very accurate conclusion.
-Overhaul the dam. Expert advice was ignored.
● The word "dam break" does not exist in people's minds.
Pan, an academician of China Academy of Engineering, introduced in his book "Millennium Dam" that the Huaihe River flood in the summer of 1950 contributed to the "Decision on Harnessing Huaihe River" made by the state in the same year 10. This decision clarifies the policy of "storing and discharging while raising funds" for harnessing the Huaihe River, and specifically formulates the strategic deployment of "building reservoirs in the upper reaches, promoting soil and water conservation in general, and taking the long-term goal of stopping Hong Xing from repairing water conservancy" and "holding temporary flood storage projects in low-lying areas to renovate the Hongru River". The "Huaihe War" thus began.
In the "Huai River War", Shimantan Reservoir was built in the upper reaches of the Red River and Banqiao Reservoir was built in the upper reaches of the Ruhe River. According to reports, there were few hydrological data at that time, and the design flood and engineering standards were very low. In engineering application, Banqiao Reservoir found cracks in water conveyance tunnel and longitudinal and transverse cracks in earth dam, so Banqiao Reservoir and Shimantan Reservoir were expanded at 1955— 1956 respectively. According to the once-in-a-century design and once-in-a-thousand check of hydraulic structures in the Soviet Union, the flood standard of Banqiao Reservoir decided to raise the dam by 3m, with the crest elevation116.34m and the breakwater elevation1/7.64m.. The newly added auxiliary spillway has a width of 300m and a bottom elevation of113.94m. Together with the original spillway and water conveyance tunnel, the maximum flood discharge capacity is1742m3, and the maximum storage capacity is 492m3, of which the storage capacity for flood regulation is 375m3. According to the 50-year return period design and 500-year return period check of Shimantan Reservoir, it is determined that the dam height is 3.5m, the crest elevation of the dam reaches109.7m, and the crest elevation of the breakwater is11.2m.. After reinforcement, the maximum storage capacity is 94.4 million cubic meters, including 70.4 million cubic meters of flood storage and the maximum discharge capacity is 390 seconds cubic meters.
During the three years after the reinforcement and expansion of Banqiao and Shimantan Reservoirs, the construction of reservoirs in the Central Plains flooded in and has not been collected so far. During the two years from 1957 to 1959, more than 100 reservoirs were built in Zhumadian area.
During the period of 1958, Henan summarized the experience of building water conservancy projects in the mountainous areas of the He Sui River Basin: "focusing on storage, focusing on small scale, focusing on self-management by commune teams". Chen Xing, then the chief engineer of Henan Water Resources Department, immediately objected: in plain areas, heavy storage and light drainage will cause serious damage to the water environment-too much surface water will cause waterlogging, and too much groundwater will easily lead to waterlogging. If the groundwater level is artificially kept too high, it will be beneficial to the accumulation of saline-alkali damage. The combination of waterlogging, waterlogging and alkali is unimaginable.
However, Chen Xing's suggestion was ignored, and the experience of "centralized storage" was widely promoted, and it was soon extended to Anhui. In Anhui Province, not only a large number of small reservoirs have sprung up in hilly areas, but also rivers in the Huaihe River Basin have been blocked by a series of "dams", resulting in fatal "intestinal obstruction" in the Huaihe River Basin in the following decades.
Chen Xing is the designer of Suyahu Reservoir in Zhumadian, Henan Province, the largest plain reservoir in the Far East. The construction of the reservoir coincided with the Great Leap Forward. A former leader of the Water Resources Department of Henan Province thought that the original design was too conservative and made several key changes without authorization. For example, he thought that "the gate design was too big", so he cut off seven gates from the original 12 hole drainage gate, leaving only five gates. At the same time, it encountered the flood diversion gate at the junction of Huaihe River, Henan and Anhui: the gate Kong Yuan was designed with 9 holes according to the displacement of 800 seconds cubic meters, but due to the ideological guidance of "focusing on storage", the hydrological data was artificially reduced and only 7 holes were built; 1959 After the sluice gate is opened, the two holes are manually blocked at 196 1.
In the "rectification" started at 196 1, Henan Province conducted a comprehensive survey of the reservoirs in the province, and abandoned some reservoirs with low design standards, poor construction quality and hidden dangers, including some large reservoirs.
However, the mistake of guiding ideology has not been really reversed, and the tendency of reinjection irrigation, ignoring river regulation and emphasizing advantages over disadvantages still persists. By the end of 1960, there were more than 100 new reservoirs in Zhumadian. In contrast, the flood discharge capacity of the Hongru River has not been enhanced, but has decreased year by year.
In fact, before the catastrophic flood in August 1975, there was a serious crisis in the upper reaches of the Huaihe River: the river was not well ventilated, the dikes were not firm, and many hidden dangers of "sick dikes" were not removed. What's more, people are not alert to the potential danger of dam failure of large reservoirs such as Banqiao and Shimantan-to be precise, the word "dam failure" simply doesn't exist in people's minds.
People believe too much in the established flood standards such as "once in a hundred years" and "once in a thousand years", and are confident that Shimantan Reservoir can control the once-in-50-year flood and protect itself from the once-in-500-year flood. Banqiao Reservoir can control the flood with a return period of 100, and it can be safe in the flood with a return period of 1000. No one has ever seen the "once-in-a-thousand-year" flood, and all the data are calculated according to the limited historical materials that people have. 1August, 975, the real flood came. The heavy rain from the sky is staggering: its rainfall is twice as high as the design standard of "once in a thousand years"!
-Heavy storage and light discharge will inevitably cause damage to the water environment.
● The guiding ideology of water conservancy construction has fallen into some misunderstandings.
The impact disaster caused by dam break has caused a devastating blow to the Hongru River basin, and the soaking disaster caused by poor drainage and high flood has aggravated the loss of this disaster-the guiding ideology of water conservancy construction has fallen into.
Some misunderstandings have undoubtedly become another source of this disaster.
At that time, because Suyahu Reservoir was not out of danger, Chen Xing, a water conservancy expert, suggested blasting the water retaining part to speed up the flood discharge. After the plan was approved by the relevant state leaders, the blasting officially started on August 14, and it took two whole days to complete all the work. After the blasting, a large number of floods in Henan poured downstream, causing tension in the middle and lower reaches of the Huaihe River. For many years, the Huaihe River has been harmed by the guiding ideology of emphasizing storage and neglecting discharge. Cofferdams have been clustered on the spillway, and the flood discharge capacity has decreased by 30-40%. Along the way, the Huaihe River flows flat and dangerous. Water conservancy experts pointed out that over the years, from the endless demand for "reservoirs", people have tasted the true taste of "heartless fire and water" by emphasizing advantages and ignoring disadvantages, and emphasizing reservoir construction and ignoring river regulation.
14 after the dam failures of Banqiao and Shimantan, Li Rui, former vice minister of water resources, pointed out meaningfully in the demonstration of the Three Gorges Project that the role of reservoirs should never be emphasized unilaterally and the river regulation should not be ignored. He said: "For river flood control, the role of dikes is absolute, and it is the most effective measure for major rivers at home and abroad. This is a long-term hard work, but it does not show the talent and grandeur of the organizer. But I believe that as long as the earth exists and rivers exist, the role of dikes is eternal ... "
Experts say that Chen Xing pointed out 20 years ago that no matter what calculation method is adopted, no matter how to improve the management of the built reservoirs, no matter how smooth the command is when the information appears, it is bound to cause damage to the water environment. However, why didn't Chen Xing's opinions not only get ignored, but also began to be used only after he was purged by politics and disaster came? It seems that the institutional causes of decision-making and personnel mistakes are worth pondering.
-Rainstorm warns the national water conservancy work.
● Qian, then Minister of Water and Electricity, said that "the responsibility lies with the Ministry of Water and Electricity".
19751late October to1early February, 65438, the Ministry of Water and Electricity held a national conference on the safety of flood control reservoirs in Zhengzhou. Minister Qian said: "... the responsibility lies with the Ministry of Water and Electricity, and I have to bear the main responsibility first. Because there has never been a dam failure accident of a large reservoir in the past, there is a paralysis thought, and it is considered that the problem of large reservoirs is not big, and there is a lack of in-depth research on the safety of large reservoirs. Second, there are problems in reservoir safety standards and flood calculation methods. For reservoir safety standards and flood calculation methods, we mainly adopt Soviet regulations. Although some improvements have been made, they have not broken through the box, studied the experience of other countries in the world, or even summed up their own experience in time to make regulations that are in line with the situation in China. Third, the reservoir management work is not well grasped. There is also a lack of clear regulations on command and dispatch, communication, standby power supply, alarm system and necessary material preparation in flood control. Banqiao and Shimantan Reservoir, when the flood control was the most tense, telecommunications were interrupted, contact was lost, and the command was ineffective, which caused great passivity. "
Qian also said: "The quality of Banqiao and Shimantan Reservoir projects is relatively good, which will bring great benefits after completion. However, due to the lack of hydrological data during the construction period, the flood design results are very unreliable. 1972 after the rainstorm occurred in Banqiao Reservoir, the management department and the design unit conducted a flood review, but they did not arouse enough vigilance and did not put forward corresponding measures, so the flood control standard was actually very low. "
Qian believes that the "7.5.8" rainstorm is a severe test for harnessing the Huaihe River and a warning for the national water conservancy work. Therefore, we must conscientiously sum up the positive and negative experiences and constantly improve the level of water conservancy work. Summarize the experience and lessons of harnessing the Huaihe River for 25 years, make a full estimate of the flood, and find out the regularity from the meteorological and historical characteristics.
No weather station predicted the heavy rain.
● The old forecaster in Zhumadian feels guilty and sorry so far.
No one reported the rainstorm from the Central Meteorological Observatory to the Henan Meteorological Observatory and then to the Zhumadian Meteorological Observatory. Today, Sun Lingxi and Wang Genyuan, 70-year-old forecasters of Zhumadian Meteorological Bureau, still feel guilty and sorry when they mention the unexpected rainstorm.
Afterwards, experts analyzed the reasons why the "75.8" rainstorm could not be accurately predicted: First, the path of the "7503" typhoon was too secret, which broke the law that the typhoon released energy on a large scale in inland areas, making people unprepared and unpredictable; Secondly, the forecaster's experience is not rich enough, and the establishment of New China is not long. China's meteorological science is still in the stage of exploration and research, and there is no mature experience to learn from. There are many grass-roots meteorological stations that still rely on the old model of air pressure, temperature and humidity curves to see the sky. Thirdly, the observation methods are backward and the communication tools are outdated. After that, meteorologists at all levels adjusted their forecasting ideas, analyzed the causes and defensive countermeasures of local typhoon-caused flood and rainstorm in a joint way, and established a variety of flood-caused rainstorm weather forecasting models.
According to the forecast of Kong Haijiang and others of Henan Meteorological Observatory, a regional rainstorm caused by landing typhoon is likely to occur in Henan Province in 2008. Therefore, the task of disaster prevention in Henan Province is still arduous in the future.
-Rainstorm disasters are not just a matter of forecasting.
● The first meteorologist who arrived at the scene at that time summed up a lot of experience.
On September 16, the reporter met with Li Zechun, an expert in weather dynamics and numerical forecasting, former director of the National Meteorological Center and academician of China Academy of Engineering. He has been engaged in the construction and scientific research of weather forecasting and numerical weather forecasting business systems for a long time and experienced the "July 8" disaster relief.
Li Zechun was the first weatherman to arrive at the scene. Recalling the scene of that year, his words are still heavy. "This experience made me deeply feel that the responsibility of meteorologists is great!" Li Zechun did a lot of investigations in the following months, and many experiences he summed up still have practical guiding significance today.
He said, first of all, we should pay attention to the important role of meteorological research in national life. Meteorological work must strengthen business concept, carry out perfect management, long-term accumulation and meteorological research; At the same time, frontline meteorologists should have rich meteorological knowledge. "When the flood occurred, Zhengzhou had a weather radar, but because of the power outage, no information was left." This matter has so far made Li Zechun feel uneasy. He believes that meteorological, hydrological, environmental protection, forestry, agriculture and other departments should be unified to form a unified natural environment observation website, and finally these materials should be managed in a unified and standardized manner to serve and apply science.
"The rainstorm is not just a matter of forecasting." Li Zechun pointed out that "man-made disasters" were equally prominent in that disaster. Mainly manifested in the reservoir construction at that time, "heavy water storage irrigation, light river regulation", in some reservoir construction "a model of fast and good province", contrary to scientific laws. In addition, when disasters happen, social organizations also have problems. They don't know how to evacuate people and provide disaster relief. Therefore, local leading departments should attach great importance to the construction of natural disaster monitoring and early warning system in the whole society, and at the same time carry out scientific disaster relief to form a good atmosphere of popular science public opinion.
Li Zechun also pointed out that some new situations at present and in the future are worthy of vigilance. "There were few chemical plants in those days, and there were relatively few sequelae left after the flood. Now some places develop chemical industry, and factories are built in dam areas. Once an accident happens, the pollution caused is immeasurable. This problem has already appeared in the typhoon in New Orleans. " He believes that the site selection of some large chemical plants must be comprehensively evaluated by meteorological, water conservancy and other departments.