5. The deadliest civil engineering incident in history, the collapse of the Banqiao Dam in 1975 resulted in the deaths of almost 200,000 people
The Banqiao Dam, situated on the River Ru in Zhumadian City, Henan province, China, was completed in June 1952 to manage regional flooding and generate hydroelectric power for the surrounding area. Functioning successfully until August 8, 1975, when, at approximately 1 am, the dam, unable to hold back record rainfalls, suffered a critical failure and collapsed. Releasing a total of 15.7 billion cubic meters of water, the resultant flood waters formed a 10-kilometer wide wave measuring 7 meters high that sprinted at speeds of almost 50 kilometers per hour across the Chinese plains. In total, an area 55 kilometers long and 15 kilometers wide was covered by the released water, creating a 12,000 square kilometer temporary lake, and killing an estimated 171,000 people.
Despite government claims to the contrary, blaming natural weather conditions, it has been determined that the dam’s failure was chiefly due to structural faults which exacerbated the dramatic increase in water capacity. Immediately after the project’s completion, cracks appeared in both the dam and the sluice gates; although repaired, it is believed that they were never returned to full strength. Equally, the sluice gates on the night of the incident were rendered ineffective due to sediment blockage. Most importantly, however, to save costs the dam only included five sluice gates. Engineers on the project had lobbied for a minimum of twelve but were overruled by management.