Banqiao and Shimantan Dam Failures (1975)

Rain and Reservoirs

In early August 1975 the year’s third typhoon moved north after landfall and met cold air over Zhumadian prefecture in Henan, producing three downpours over three days. According to a 2007 retrospective in Youth Reference, the third and heaviest, beginning at noon on 7 August, dropped 853 mm of rain in six hours at Linzhuang near the Banqiao reservoir. Banqiao and Shimantan were among the first reservoirs built in 1951 under the Huai River control programme, and Banqiao was known as an “iron dam”. The article says four dry years and a severe 1975 drought had led Banqiao to hold 32 million cubic metres above normal, and that Chen Xing, chief engineer of the Henan Water Resources Bureau, proposed blowing up the auxiliary spillway, but the telephone lines to the dam were down. The World of Chinese wrote in 2019 that before communications failed the authorities had told Banqiao not to open its sluice gates fully, to avoid worsening flooding downstream.

The Failures of 8 August

According to Youth Reference, Shimantan failed first at 00:30 on 8 August; at 01:30, just as the rain stopped, the Banqiao dam collapsed and the reservoir emptied within five hours. Together with two medium and 58 small reservoirs that failed within hours, 5.7 billion cubic metres of water turned ten counties into a sea. The flood destroyed 103 km of the Beijing–Guangzhou railway, cutting it for 18 days; in Wencheng, which had no warning, half of more than 36,000 people died. The American engineer Wayne J. Graham wrote in 2010 that Banqiao, Shimantan and 60 other dams failed, “5,240,000 houses collapsed” and more than ten million people were affected.

Relief and the Bantai Sluice

On 9 August the Zhumadian prefectural Party committee cabled the Centre that more than three million people had been stranded on roofs and trees for two or three days. The Centre formed a delegation under Vice-Premier Ji Dengkui; more than 70,000 troops were sent and the state allocated over 370 million yuan in relief. To drain the trapped water, Vice-Premier Li Xiannian told a meeting early on 14 August: “To save people, wherever you say to blow up, we agree to blow up”; troops then blew up the Bantai sluice in Anhui on 14 August, releasing 5.513 billion cubic metres. Youth Reference notes that Anhui had built the sluice in 1958 to hold back water from Henan, that the two provinces had long quarrelled over drainage, and that 1.5 million people in six unflooded counties of Fuyang, Anhui, “bore the greatest sacrifice.”

The Death Toll Dispute

The official death toll is 26,000. Youth Reference quotes Minister of Water Resources and Electric Power Qian Zhengying describing it as the flood with the largest affected area and the most deaths since 1949. Other estimates differ widely: Yi Si’s 1998 essay in a collection edited by Dai Qing puts the dead at 85,000; The World of Chinese attributes the 85,000 figure to “estimates compiled in 1989”; and Graham gives “fatality estimates ranging from 26,000 to 230,000.” The World of Chinese adds that many, including a Henan water-resources official, believe the official figure understates the true scale.

The disaster long remained unknown abroad. Graham writes that “Information on these failures remained hidden from the outside world for two decades”; The World of Chinese says that disaster death tolls were then treated as state secrets and that a 2005 seminar in Beijing lifted restrictions on casualty figures.

Causes and Lessons

In November 1975 Qian Zhengying chaired a national conference on flood control and reservoir safety in Zhengzhou and accepted responsibility: “Responsibility lies with the Ministry, and first of all I bear the main responsibility.” Among the causes she listed were complacency because no large dam had failed before; safety standards and flood calculations that “largely copied Soviet rules without regulations suited to China”; the lack of clear emergency rules, with Banqiao and Shimantan essentially unprepared for the flood season and command breaking down when communications failed; and ineffective flood-control command. The hydrologist Wang Guoan argues that the main cause was not low flood-control standards but design flood values that were too small, and that foreign experience must not be copied mechanically and important earth-rock dams need emergency spillways. Shimantan was rebuilt after 1976; Banqiao’s reconstruction was approved in 1978, halted in 1980, resumed in 1986 and completed in May 1992.