1887 Yellow River flood

The Yellow River in China is prone to flooding, due to the broad expanse of largely flat land around it. The 1887 Yellow River floods devastated the area, killing between 900,000-2,000,000 people. It was one of the deadliest natural disasters ever recorded.
For centuries, the farmers living near the Yellow River had built to contain the rising waters, caused by silt accumulation on the riverbed. In 1887, this rising riverbed, coupled with days of heavy rain, overcame the dikes, causing a massive flood.
The waters of the Yellow River are generally thought to have broken through the dikes in Huayankou, near the city of Zhengzhou in Henan province. Owing to the low-lying plains near the area, the flood spread very quickly throughout Northern China, covering an estimate 50,000 square miles, swamping agricultural settlements and commercial centers. After the flood, two million were left homeless. The resulting pandemic and lack of basic essentials claimed as many lives as those lost directly by the flood itself. It was one of the worst floods in history, though the later 1931 Yellow River flood may have killed as many as two million.