The Deadliest Weather-Related Catastrophe You Probably Never Heard Of
In early August 1975, Typhoon Nina made landfall along the coast of China near Shanghai. The storm weakened as it moved inland and merged with a cold front that straddled Henan Province (in central China), resulting in the development of a series of near-stationary thunderstorms in and around the town of Linzhuang. The greatest short-term rainfall event in modern Chinese records ensued: some 1060 mm (41.73”) of rain fell in just 24 hours. The Banqiao Dam on the Ru River near Linzhuang, failed as a result of the rains and collapsed on August 7-8, sending a wave some 6 miles wide and 10–23 feet deep across the plains below. As a result some 100,000–230,000 people perished. By some accounts, this makes Typhoon Nina the fourth-deadliest tropical storm in modern world history.
The wide range in fatality estimates is because many of the deaths occurred as a result of famine and disease following the flood itself. The exact figures for each source of fatalities remains obscure. If the high-end figure of 230,000 is correct, then the event would rank as not only the fourth-deadliest tropical storm on record but perhaps the sixth-deadliest natural disaster of any kind since 1900.
The Banquao Dam was constructed with the help of Soviet consultants in 1951 as a project to control flooding and generate electricity. It was designed to survive a “once in 1000 years” return rainfall event (the area normally receives about 1000mm/40” of rainfall a year) which was calculated as being 300 mm (11.81”) of rainfall over 24 hours. In reality, that much rain fell in just two hours during the 1975 storm, with following maximum precipitation point rainfalls measured:
189.5 mm (7.46”) in 1 hour
494.6 mm (19.47”) in 3 hours
830.0 mm (32.68”) in 6 hours (world record)
954.4 mm (37.57”) in 12 hours
1060 mm (41.73”) in 24 hours
1629 mm (64.13”) in 3 days