"The deadliest natural disaster ever recorded occurred through the winter, spring, and summer of 1931 in central China. There are three major rivers draining this area, the Yangtze, the Yellow, and the Huai. All three flooded catastrophically, because the winter snowstorms were particularly heavy in the mountains around the river basins, and when spring began, all this snow melted and flowed into the rivers.
Then the spring brought particularly heavy rains. Then the cyclone season, which usually brings only 2 storms per year, brought 10, 7 of them in July. All this water swelled the three major rivers, especially the Yellow River, and because they drain a very large, very flat area of China, somewhere between 3.7 and 4 million people were drowned or starved.
Nanjing City, China’s capital at the time, became an island surrounded by over 100,000 square kilometers of water, more area than the state of Indiana, or all of Portugal."