Banqiao Dam Failure 1975
One of the worst dam failure to ever happened in human history.
Also known as the Henan(河南) 75.8 disaster, occurred in August 1975 at Henan province, China. When the hot humid air brought by typhoon Nina combined with the cold air from the north created the perfect environment for sustained heavy rain. On the night of August 8th, Banqiao dam collapsed catastrophically. Drowning at least 26,000 people (with estimates upward to 80,000 casualties). Combined with the fact that the communists government at the time couldn’t react swiftly, widespread famine and diseases took 200,000 additional lives.
How did it happen exactly? The story starts at the 1940s. During the late 40s, a series of floods occurred on the Huai river (淮河), so the Mao government decided to build a series of dams to improve the control on the river. However, the engineers at that time focused on the dam’s ability to store water and neglected the need of draining in case of heavy rain. With the help of Soviet engineers, the Chinese government built more than one hundred dams on the river between 1957 and 1959 (insane!). Then came the era of Cultural Revolution led by Maoist (1965–1975). During that period of time, people were busy fighting each others on various topics and the society stagnated. Without proper maintenance and awareness on possible floods, a terrible terrible disaster was brewing.
It was the 1975 western Pacific typhoon season. On July 31 1975, typhoon Nina was formed near Guam Island. With perfect condition for a tropical cyclone to develop, typhoon Nina soon turned into a very strong typhoon with windspeed equivalent to a category 5 hurricane. After penetrating Taiwan, typhoon Nina made landfall from the Fujian province on August 4 1975. Combined with the burst of humid air all the way from southern hemisphere crossing the equator, heavy rain followed throughout the entirety of central China. More than nineteen thousand square kilometers of land experienced more than 40 cm of rain (15.75 in.). On the upstream of the Banqiao dam, 1 meter of rain is recorded in a day! From August 5th to 7th, the rain never stopped pouring, and the water level at Banqiao dam rose relentlessly. On August 6th, the water level has became so high at 112m, which is already two meters more than the designed maximum water level. Even worse, on the night of August 5th, due to the torrential rain in the region, the Banqiao dam control center has lost both telephone and road access to the outside world. The control center’s last resort of communication was via telegraph. At the midnight of August 6th, workers at Banqiao dam opened all the spillway, desperately trying to lower the water level. Sadly, the miscalculation made by soviet engineers two decades ago meant that their is no way that the designed spillway is enough to counter this kind of rainfall. And the water level kept on rising as the rain continued to pour. At the night of August 7th, 7 smaller dams upstream have collapsed. Under the assistance of the military, workers sent the last morse coded telegraph to Beijing saying that water has started to flow over the top of the dam. They tried to warned all the inhabitants down stream by firing flares and even gunshots from their rifles, but the bad weather meant that no one actually got any warnings. At 1 a.m. August 8th, Banqiao dam collapsed along with 58 other reservoirs with various sizes on the same river.
600 million cubic meters of water rushed down the valley (that is the same amount of water that flows through Niagra falls in two whole days!), arriving at the first town (文城公社) and killing 9600 people almost instantly. One hour after the collapse of Banqiao dam, a water wave with height of 7 to 10 meters (23–33 ft.) struct the city (遂平城) 45 km (28 mi.) downstream causing even more damage and casualties. In the following days, People’s Liberation Army (PLA) rushed into the affected areas to carry out search and rescue operations. Five days after the dam collapsed, there are still more than one million people submerged in water waiting for rescue. With bodies floating everywhere, hygiene conditions deteriorated. Widespread flu, dysentery, hepatitis and even encephalitis ( brain infection) took the lives of more than one hundred thousand people. The PRC government made the actual casualties figures a secret to save face. Criticism and the cries of the refugees were never heard. This disaster that killed hundred of thousand of people and destroyed millions of houses could have been prevented, or at least, reduced. The bureaucracy and turbulent society meant that people didn’t really anticipated such things to happen. It is a true tragedy, and the nature is not the one to blame.
This is my first ever medium article! I will continue to cover more dire disaster throughout modern history. Feel free to follow me so you won’t miss any interesting but sad stories!
