According to LiveScience.com, the 1931 Yangtze River flood in central China had the most casualties of any modern natural disaster. The U.S. National Oceanic and Atmospheric Administration estimates 3.7 million deaths as a direct result of the flood, and over 51 million people were affected overall.
The flood affected all populations living alongside the Yangtze River, which stretches across central China. For this reason, the flood's casualties were widespread. In addition to drowning, deaths occurred as a result of famine and starvation after much of the country's food supplies were destroyed, as well as disease from the resulting wet environment.