Dams DisastersDisasters

Dams Disasters

A dam is a barrier across flowing water that obstructs, directs or slows down the flow, often creating a reservoir, lake or impoundments. Most dams have a section called a spillway or weir over or through which water flows, either intermittently or continuously, and some have hydroelectric power generation systems installed.

Oroville Dam DisasterDams are considered "installations containing dangerous forces" under International Humanitarian Law due to the massive impact of a possible destruction on the civilian population and the environment. Dam failures are comparatively rare, but can cause immense damage and loss of life when they occur.

In 1975 the failure of the Banqiao Reservoir Dam and other dams in Henan Province, China caused more casualties than any other dam failure in history. The disaster killed an estimated 171,000 people and 11 million people lost their homes.

The Banqiao Reservoir Dam failure happened when Typhoon Nina pelted the region with the heaviest rains ever recorded in the area. More than a year’s worth of water fell in 24 hours. The previous record was 800 mm (31.5”) of rain, and the stalled typhoon Nina dropped a new record of 1060 mm (41.73”).

The rainfall caused massive downstream flooding and, because of the flooded downstream areas, one request to open the dam was rejected on August 6. On August 7, the request to open the dam was accepted but this information did not reach the dam, as the storm had brought down the telegraph wires.  The under-designed sluice gates were unable to handle the water volume and the first dam failure warning was sent. The water crested on August 8 at 0.3 meter (0.0984’) higher than the protection wall on the dam, which failed. 62 other dams in the Huai river basin also failed. More details