The Worst Flood in History (and 9 Other Catastrophic Floods)

Often cited as the deadliest floods in history, the 1931 China floods affected the Yangtze River, Yellow River (Huang He) and Huai River.

Triggered by torrential rainfall and snowmelt, the floodwaters submerged massive areas in Henan Province and beyond.

The estimated death toll ranges from 1 to 4 million people, with tens of thousands drowning and many more dying from famine and disease. The devastation across central China remains unmatched in scale [source: Disasterhistory.org].

In August 1975, Typhoon Nina brought extreme rainfall to Henan Province, causing the Banqiao Dam and dozens of others to fail. The flood swept across the region, killing an estimated 26,000 to 240,000 people.

Poor planning and outdated infrastructure contributed to the tragedy, which led to widespread destruction and raised global awareness of dam safety.

When the South Fork Dam failed after days of heavy rain, 20 million tons (18.1 million metric tons) of water surged into Johnstown, Pennsylvania.

The wave obliterated the town in minutes, killing over 2,200 people. This event stands as one of the worst floods in American history, highlighting the dangers of inadequate dam maintenance.

This river flood devastated the Mississippi River Basin and is one of the most destructive floods in U.S. history. Torrential rains caused the Mississippi and Missouri Rivers to swell, breaching levees and inundating 27,000 square miles (70,000 square kilometers).

Over half a million people were directly affected, and the floodwaters reached as far south as Louisiana.

Triggered by weeks of heavy rain, the 1937 Ohio River flood destroyed entire towns and cities along the river's path. Cities like Louisville and Cincinnati were submerged.

This devastating flood caused over 1 million evacuations and resulted in nearly 400 deaths, spurring major changes in flood insurance and early warning systems.

Hurricane Katrina brought catastrophic floods to New Orleans in August 2005. Storm surges and levee failures left 80 percent of the city underwater. The estimated death toll surpassed 1,800, with billions in property damage. Katrina remains one of the most devastating natural disasters in modern U.S. history.

Though primarily known as a cyclone, the storm surge from this disaster caused massive flooding and the deaths of over 300,000 people in East Pakistan (now Bangladesh). The Bhola Cyclone is more than a notable flood; it remains one of the deadliest natural disasters ever recorded.

A powerful storm and high tides led to the North Sea flood, affecting the Netherlands, the United Kingdom and Belgium. More than 2,500 people died, and the event prompted massive upgrades to dikes and early warning systems throughout Europe.

In June 1972, heavy rainfall overwhelmed dams near Rapid City, South Dakota. A wall of water rushed through the town, killing 238 people. This tragic event led to significant improvements in U.S. flood management and preparedness.

Caused by a powerful hurricane, the Galveston flood remains the deadliest natural disaster in U.S. history. The storm surge swept over the city, killing between 6,000 and 12,000 people and destroying most of the infrastructure. The aftermath led to a seawall and raised land to prevent future catastrophe.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.