Three Gorges Dam

Its primary purpose was flood control.

An excerpt from the article 12 facts about Three Gorges Dam
The Yangtze River's occasional flooding caused both mild and major devastation in the basin area. The dam eased flood pressure by the controlled release of rainwater from its reservoir. However, it did not prevent flooding, as one of the biggest occurred in 2010, and caused the death of nearly 400 people, and over US$50 billion of damage.