10 of the World’s Deadliest Dam Failures

Living in the shadow of a large dam means you have placed your trust in the engineers who designed it. Because if there were any errors in their calculations, the result could be a deadly catastrophe. When a dam breaches, the consequent water surge can carry away all before it, destroying property and killing humans and livestock. As this list shows, when mistakes are made during dam construction, the results can be truly horrific. Some final words of reassurance: the vast majority of dams don’t fail!

A fierce typhoon hit the western Chinese province of Henan in August 1975, which had devastating consequences. There was a massive dam standing 387 feet (118 meters) tall in the province, spanning the Ru River. Completed in 1952, the Banqiao dam was constructed with an interior of tightly packed clay with an overlay of sand. Its purpose was to provide irrigation for farmland in the adjacent Huai River Basin. The reservoir created by the dam had a capacity of 158 billion gallons (600 billion liters).The dam had been designed to withstand anything but a flood level expected to occur only once in a thousand years. Unfortunately, that “once” came along when a ferocious typhoon appeared just five years after the dam was finished. This cataclysmic weather event was so severe that 55 inches (140 centimeters) of rain fell in three days on an area that normally had 32 inches (81 centimeters) in an entire year. That was too much for the Banqiao dam, and it failed, releasing a deluge 33 feet (10 meters) high and up to 7 miles (11.3 kilometers) wide. Firm casualty figures are hard to come by, but by one estimate, as many as 230,000 perished