Banqiao Dam

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The Banqiao Reservoir Dam (simplified Chinese : ; traditional Chinese :板橋水庫大壩; pinyin :Bǎnqiáo Shuǐkù Dàbà) is a dam on the River Ru in Zhumadian City, Henan province, China. Its failure in 1975 caused as many as 230,000 deaths. [1] The dam was subsequently rebuilt.

Simplified Chinese characters standardized Chinese characters developed in mainland China

Simplified Chinese characters are standardized Chinese characters prescribed in the Table of General Standard Chinese Characters for use in mainland China. Along with traditional Chinese characters, they are one of the two standard character sets of the contemporary Chinese written language. The government of the People's Republic of China in mainland China has promoted them for use in printing since the 1950s and 1960s to encourage literacy. They are officially used in the People's Republic of China and Singapore.

Traditional Chinese characters

Traditional Chinese characters are Chinese characters in any character set that does not contain newly created characters or character substitutions performed after 1946. They are most commonly the characters in the standardized character sets of Taiwan, of Hong Kong and Macau, and in the Kangxi Dictionary. The modern shapes of traditional Chinese characters first appeared with the emergence of the clerical script during the Han Dynasty, and have been more or less stable since the 5th century.

Hanyu Pinyin, often abbreviated to pinyin, is the official romanization system for Standard Chinese in mainland China and to some extent in Taiwan. It is often used to teach Standard Mandarin Chinese, which is normally written using Chinese characters. The system includes four diacritics denoting tones. Pinyin without tone marks is used to spell Chinese names and words in languages written with the Latin alphabet, and also in certain computer input methods to enter Chinese characters.


The Banqiao dam and Shimantan Reservoir Dam (simplified Chinese : ; traditional Chinese :石漫灘水庫大壩; pinyin :Shímàntān Shuǐkù Dàbà) are among 62 dams in Zhumadian that failed catastrophically or were intentionally destroyed in 1975 during Typhoon Nina.

Dam A barrier that stops or restricts the flow of surface or underground streams

A dam is a barrier that stops or restricts the flow of water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect water or for storage of water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. The earliest known dam is the Jawa Dam in Jordan, dating to 3,000 BC.

Zhumadian Prefecture-level city in Henan, Peoples Republic of China

Zhumadian is a prefecture-level city in southern Henan province, China. It borders Xinyang to the south, Nanyang to the west, Pingdingshan to the northwest, Luohe to the north, Zhoukou to the northeast, and the province of Anhui to the east.

A catastrophic failure is a sudden and total failure from which recovery is impossible. Catastrophic failures often lead to cascading systems failure. The term is most commonly used for structural failures, but has often been extended to many other disciplines in which total and irrecoverable loss occurs. Such failures are investigated using the methods of forensic engineering, which aims to isolate the cause or causes of failure.


Approximate location of Banqiao Dam Banqiaomap.png
Approximate location of Banqiao Dam

Construction of the Banqiao dam began in April 1951 on the Ru River with the help of Soviet consultants as part of a project to control flooding and provide electrical power generation. The construction was a response to severe flooding in the Huai River Basin in 1949 and 1950. [2] The dam was completed in June 1952. Because of the absence of hydrology data, the design standard was lower than usual. After the 1954 Huai River great flood, the upstream reservoirs including Banqiao were extended, constructed, and consolidated. Banqiao Dam was increased in height by three meters. The dam crest level was 116.34 meters above sea level and the crest level of the wave protection wall was 117.64 meters above sea level. The total capacity of the reservoir was 492 million m3 (398,000 acre feet), with 375 million m3 (304,000 acre feet) reserved for flood storage. The dam was made of clay and was 24.5 meters high. The maximum discharge of the reservoir was 1742 m3/s.

Flood Overflow of water that submerges land that is not normally submerged

A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrology and are of significant concern in agriculture, civil engineering and public health.

Huai River major river in China

The Huai River, formerly romanized as the Hwai, is a major river in China. It is located about midway between the Yellow River and Yangtze, the two largest rivers in China, and like them runs from west to east. Historically draining directly into the Yellow Sea, floods have changed the course of the river such that it is now a major tributary of the Yangtze. The Huai is notoriously vulnerable to flooding.

Clay A finely-grained natural rock or soil material that combines one or more clay minerals

Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz (SiO2), metal oxides (Al2O3, MgO etc.) and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to particle size and geometry as well as water content, and become hard, brittle and non–plastic upon drying or firing. Depending on the soil's content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red.

Cracks in the dam and sluice gates appeared after completion due to construction and engineering errors. They were repaired with the advice from Soviet engineers and the new design, dubbed the iron dam, was considered unbreakable.

Sluice A water channel controlled at its head by a gate

A sluice is a water channel controlled at its head by a gate. A mill race, leet, flume, penstock or lade is a sluice channelling water toward a water mill. The terms sluice, sluice gate, knife gate, and slide gate are used interchangeably in the water and wastewater control industry.

Soviet Union 1922–1991 country in Europe and Asia

The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a socialist state in Eurasia that existed from 30 December 1922 to 26 December 1991. Nominally a union of multiple national Soviet republics, its government and economy were highly centralized. The country was a one-party state, governed by the Communist Party with Moscow as its capital in its largest republic, the Russian Soviet Federative Socialist Republic. Other major urban centres were Leningrad, Kiev, Minsk, Alma-Ata, and Novosibirsk.

Chen Xing (陈惺), one of China's foremost hydrologists, was involved in the design of the dam. He was also a vocal critic of the government's dam building policy, which involved many dams in the basin. He had recommended 12 sluice gates for the Banqiao Dam, but this was criticized as being too conservative, and the number was reduced to five. Other dams in the project, including the Shimantan Dam, had a similar reduction of safety features and Chen was removed from the project. In 1961, after problems with the water system were revealed, he was brought back to help. Chen continued to be an outspoken critic of the system and was again removed from the project.

Chen Xing was one of China's foremost hydrologists and was involved in the design of the Banqiao Dam.

1975 Banqiao Dam flood

Rough diagram of waterflow during the Banqiao Dam failure Banqiao Dam Failture Waterflow.png
Rough diagram of waterflow during the Banqiao Dam failure

Officially, the dam failure was a natural as opposed to man-made disaster, with government sources placing an emphasis on the amount of rainfall as opposed to poor engineering and construction. The People's Daily has maintained that the dam was designed to survive a once-in-1000-years flood (300 mm of rainfall per day) but a once-in-2000-years flood occurred in August 1975, following the collision of Typhoon Nina and a cold front. The typhoon was blocked for two days before its direction ultimately changed from northeastward to westward. [3] As a result of this near stationary thunderstorm system, more than a year's worth of rain fell within 24 hours (new records were set, at 189.5 mm (7.46 inches) rainfall per hour and 1060 mm (41.73 inches) per day, exceeding the average annual precipitation of about 800 mm (31.5 inches)), [4] which weather forecasts failed to predict. [4] China Central Television reported that the typhoon disappeared from radar as it degraded. [5] According to Xinhua, [6] the forecast was for rainfall of 100 mm by the Beijing-based Central Meteorological Observatory.

<i>Peoples Daily</i> daily newspaper of the Central Committee of the Communist Party of China

The People's Daily is the biggest newspaper group in China. The paper is an official newspaper of the Central Committee of the Communist Party of China, published worldwide with a circulation of 3 million. In addition to its main Chinese-language edition, it has editions in English, Japanese, French, Spanish, Portuguese, Russian, Arabic, Tibetan, Kazakh, Uyghur, Zhuang, Mongolian, and other minority languages in China. The newspaper provides direct information on the policies and viewpoints of the Communist Party.

Typhoon Nina (1975) Pacific typhoon in 1975

Typhoon Nina, known in the Philippines as Typhoon Bebeng, was the fourth-deadliest tropical cyclone on record. At least 229,000 people died after the Banqiao Dam collapsed and devastated areas downstream. The collapse of the dam due to heavy floods also caused a string of smaller dams to collapse, adding more damage caused by the typhoon.

Cold front leading edge of a cooler mass of air

A cold front is the leading edge of a cooler mass of air, replacing at ground level a warmer mass of air, which lies within a fairly sharp surface trough of low pressure. It forms in the wake of an extratropical cyclone, at the leading edge of its cold air advection pattern, which is also known as the cyclone's dry conveyor belt circulation. Temperature changes across the boundary can exceed 30 °C (54 °F). When enough moisture is present, rain can occur along the boundary. If there is significant instability along the boundary, a narrow line of thunderstorms can form along the frontal zone. If instability is less, a broad shield of rain can move in behind the front, which increases the temperature difference across the boundary. Cold fronts are stronger in the fall and spring transition seasons and weakest during the summer.

Communication with the dam was largely lost due to failures. On August 6, a request to open the dam was rejected because of the existing flooding in downstream areas. On August 7 the request was accepted, but the telegrams failed to reach the dam. [5] The sluice gates were not able to handle the overflow of water partially due to sedimentation blockage. [7] On August 7 at 21:30, the People's Liberation Army Unit 34450 (by name the 2nd Artillery Division in residence at Queshan county), which was deployed on the Banqiao Dam, sent the first dam failure warning via telegraph. On August 8, at 01:00, water at the Banqiao crested at the 117.94 m level above sea level, or 0.3 meter higher than the wave protection wall on the dam, and it failed. The same storm caused the failure of 62 dams in total. The runoff of Banqiao Dam was 13,000 m3 per second in vs. 78,800 m3 per second out, and as a result 701 million m3 of water were released in 6 hours, [4] while 1.67 billion m3 of water were released in 5.5 hours at an upriver Shimantan Dam, and 15.738 billion m3 of water were released in total.

The resulting flood waters caused a wave 10 kilometers (6.2 mi) wide and 3–7 meters (9.8–23.0 ft) high in Suiping (遂平) that rushed onto the plains below at nearly 50 kilometers per hour (31 mph), almost wiping out an area 55 kilometers (34 mi) long and 15 kilometers (9.3 mi) wide, and creating temporary lakes as large as 12,000 square kilometers (4,600 sq mi). Seven county seats, Suiping, Xiping (西平), Ru'nan (汝南), Pingyu (平舆), Xincai (新蔡), Luohe (漯河), and Linquan (临泉) were inundated, as were thousands of square kilometers of countryside and countless communities. Evacuation orders had not been fully delivered due to weather conditions and poor communications. Telegraphs failed, signal flares fired by Unit 34450 were misunderstood, telephones were rare, and some messengers were caught by the flood. While only 827 out of 6,000 people died in the evacuated community of Shahedian just below Banqiao Dam, half of a total of 36,000 people died in the unevacuated Wencheng commune of Suipin County next to Shahedian, and the Daowencheng Commune was wiped from the map, killing all 9,600 citizens. [4] Although a large number of people were reported as lost at first, many of them later returned home. A 2005 book compiled by the Archives Bureau of Suiping county reports that more than 230,000 were carried away by water, in which 18,869 died. [8] It has been reported that 90,000 - 230,000 people were killed as a result of the dam breaking.

To protect other dams from failure, several flood diversion areas were evacuated and inundated, and several dams were deliberately destroyed by air strikes to release water in desired directions. The Nihewa and Laowangpo flood diversion areas downstream of the dams soon exceeded their capacity and gave up part of their storage on August 8, forcing more flood diversion areas to begin to evacuate. The dikes on the Quan River collapsed in the evening of August 9, and the entire Linquan county in Fuyang, Anhui was inundated. As the Boshan Dam, with a capacity of 400 million m3, crested and the water released from the failures of Banqiao and Shimantan was rushing downstream, air strikes were made against several other dams to protect the Suya Lake dam, already holding 1.2 billion m3 of water. [9] Suya Lake won only a temporary reprieve, as both it and Boshan became eventual targets. Finally, the Bantai Dam, holding 5.7 billion m3 of water, was bombed. [10]

The Jingguang Railway, a major artery from Beijing to Guangzhou, was cut for 18 days, as were other crucial communications lines. Although 42,618 People's Liberation Army troops were deployed for disaster relief, all communication to and from the cities was cut. [4] Nine days later there were still over a million people trapped by the waters, who relied on airdrops of food and were unreachable by disaster relief workers. Epidemics and famine devastated the trapped survivors. The damage of the Zhumadian area was estimated to be about CN¥3.5 billion ( US$513 million). [11] The Zhumadian government appealed to the whole nation for help, and received more than CN¥300 million (US$44,000,000) in donations. [12]

After the flood, a summit of National Flood Prevention and Reservoir Security at Zhengzhou, Henan was held by the Department of Water Conservancy and Electricity, and a nationwide reservoir security examination was performed. Chen Xing was again brought back to the project.


According to the Hydrology Department of Henan Province, approximately 26,000 people died in the province [13] from flooding and another 145,000 died during subsequent epidemics and famine. In addition, about 5,960,000 buildings collapsed, and 11 million residents were affected. Unofficial estimates of the number of people killed by the disaster have run as high as 230,000 people. [14] The death toll of this disaster was declassified in 2005. [4]


Within eleven years of the dam failure, the lower reach of the River Ru, esp. Zhumadian City, experienced several more disastrous floods. After many feasibility studies, the new Banqiao Reservoir reconstruction was listed as a key national project of The Seventh Five-Year Plan of China. The project owner was Huai River Water Resources Commission. The construction contractor was Changjiang Gezhouba Engineering Bureau. By the end of 1986, the rebuilding project commenced. On June 5, 1993, the project was certified by the Chinese government.

The reconstructed Banqiao Reservoir controls a catchment area of 768 km2 (297 sq mi). The maximum reserve capacity is 675 million m3 (178 billion gallons), a capacity increase of 34% above the capacity of the failed dam. The effective storage is 256 million m3 (67.6 billion gallons) and the corresponding normal high water level is 111.5 m (366 ft) above sea level. The flood control storage is 457 million m3 (121 billion gallons). The dam is made of clay and is 3,720 m (12,200 ft) long and 50.5 m (166 ft) high. The dam crest level is 120 m (390 ft) above sea level. The maximum discharge of the reservoir is 15000 m3/s (about 3.96 million gallons/s).


After the disaster of the Banqiao dam failure, the Chinese government became very focused on surveillance, repair, and consolidation of reservoir dams. China has 87,000 reservoirs across the country; most of which were built in the 1950s–1970s using low construction standards. Most of these reservoirs are in serious disrepair, posing challenges to the prevention and control of flood-triggered geological disasters in areas with a population of 130 million or more. China's medium and small rivers are considered to be the Achilles' heel in the country's river control systems. According to a report from 2010, by the Ministry of Water Resources, China has invested CN¥64.9 billion (US$9.72 billion) since the 1998 Yangtze River floods in repairing and consolidating the country's 9,197 degraded reservoirs, of which 2,397 are large or medium-sized, and 6,800 are key small reservoirs. [15]

See also

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  11. The 30 Year Anniversary of the August, 1975 flood
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Coordinates: 32°58′58″N113°37′24″E / 32.98278°N 113.62333°E / 32.98278; 113.62333