Water power: Falling water

Dams and risk

Dams hold back vast volumes of water at enormous pressures. If a dam breaks, the resulting flood of water is deadly. Engineers must anticipate the worst possible weather and rain scenarios in order to calculate how strong to build the dam wall. Many lives are at stake.

The Banqiao Dam in China, built in the 1950's was designed to withstand a storm so powerful that it would occur only once in a thousand years. Unfortunately in August 1975, a once in TWO thousand years grade storm occured and the dam collapsed. 171,000 people died either from flooding, or the disease and starvation epidemics that followed. More details at Wikipedia

Case study: The Three Gorges Dam, China