Banqiao Dam Flood (1975)

Typhoon Nina struck China's Henan Province in August 1975. The Banqiao Dam was one of 62 dams that collapsed, causing extraordinary loss of life and catastrophic damage. The death toll was 26,000 from flooding, with additional deaths estimated at 145,000 from epidemics and famine following the flooding.

In the 1950s, the Banqiao Dam was built on the Ru River to help manage flooding on the Yellow River. The [Page 33]dam, designed for a 1,000-year flood, was 387 feet high with a storage capacity of 492 million cubic meters. Upon completion, cracks in the dam appeared as a result of construction and engineering errors; these cracks were repaired, and the dam was considered invincible.

Following days of earlier storms, Typhoon Nina produced flooding that was twice the 1,000-year level, eventually setting off a cascading series of dam failures. At 12:30 A.M. on August 8, the upstream Shimantan Dam collapsed. By 1:00 A.M., the Banqiao Dam had failed as well. Eventually, a total of 62 dams would collapse.

The dam collapses produced a wave 9–23 feet high and 6 miles wide, traveling at close to 30 miles per hour. Pooling created lakes as large as 750 square miles that would later prevent disaster relief from reaching the area. Over 15 billion tons of water was released in the dam collapses.

No evacuation plans were in place for the region, and there was no early warning system. However, evacuation orders were delivered to some communities, thereby improving survival rates in those areas. Not all evacuation orders were received by the communities due to weather conditions, poor communication, and messengers becoming trapped by the water. These communication failures contributed greatly to loss of life.

For survivors of the initial flooding, help was delayed by destruction of communication and transportation infrastructure, including the major railway. Residual lakes formed by the influx of water impeded travel and communication. Nine days after the disaster, over one million people remained trapped by water, and could not be reached to receive aid. The People's Liberation Army was deployed for disaster relief, but the extent of the infrastructure damage meant that airdrops were the only source of relief.