In early 1931, melting snow and ice flowed downstream and arrived in the middle course of the Yangtze during a period of heavy spring rain.

Ordinarily, the region experienced three periods of high water during the spring, summer and fall, respectively; however, in early 1931, there was a single continuous deluge.

The floods inundated approximately 180,000 square kilometres (69,000 sq mi) – an area equivalent in size to England and half of Scotland, or the states of New York, New Jersey, and Connecticut combined.

Contemporary studies conducted by John Lossing Buck allege that at least 150,000 people had drowned in the first few months of the flood, with hundreds of thousands more dying of starvation and disease over the following year.

[8][18] The most lethal effect of the flood was the diseases that swept through the refugee population due to displacement, overcrowding, and the breakdown of sanitation.

When the city itself was inundated in the early summer and after a catastrophic dike failure at just before 6:00 AM on 27 July,[20]: 270  around 782,189 urban citizens and rural refugees were left homeless.

At that time no one knew whether the water would subside or rise even higher.The city of Nanjing, then the capital of Republican China, was also severely affected by the disaster.

[8] One of the most disastrous single events during the flood occurred on 25 August 1931, when the water rushing through the Grand Canal washed away dikes near Gaoyou Lake.

[21] Thomas Harnsberger, a missionary of the Presbyterian Church in Taizhou, Jiangsu, was one of the two central figures (alongside General Wang Shuxiang,[22] a PhD in hydraulics) who supervised the rebuilding of the dikes at Lake Gaoyou, as well as securing the funds for it.

China’s attention was on a civil war between the Communists and Nationalists and the Japanese were invading in the North, while the world was deep into the Great Depression.

Although Song Ziwen remained the head of the commission, the day-to-day running the relief effort was entrusted to John Hope Simpson, a British refugee expert.

[28] In the wake of the disaster, the government set up organizations such as the Huai River Conservancy Commission to address flood problems.

[29] As part of an anti-superstition campaign by the Kuomintang Government, a Dragon King Temple was demolished in Wuhan shortly before the flood-hit.

As a response, prominent officials, including He Baohua, mayor of Wuhan, and Xia Douyin, then the local garrison commander and later governor of Hubei Province, held ritual ceremonies and kowtowed to the deity.

Li Siguang, a prominent scientist and minister of geological resources, told Mao he would commit suicide if he could not stop the construction of the dam.

[29] The project did not move beyond the planning stage in Mao's time, due to a lack of resources, rising Sino-Soviet tensions and the disruptions of the Great Leap Forward.

[29] The project was restarted in the 1980s, and the hydroelectric Three Gorges Dam began full operation in 2012, becoming the world's largest power station in terms of installed capacity.