What caused massive flooding in beijing in 2012?

In a twenty-hour period on July 21, 2012, a flash flood hit the city of Beijing in the People's Republic of China. Within a day of the flooding, 56,933 people had been evacuated, while the floodwaters killed 79 people,[1]causing at least 10 billion Yuan (US $1.6 billion) in damages and destroying at least 8,200 homes.[2] In the city, more than 1.6 million people were affected by the flood overall.[3]

July 2012 Beijing flood

Flights delayed in Beijing Capital International Airport, Terminal 2

DateJuly 21, 2012 (CST)Location People's Republic of China (Beijing)Deaths77+ (26 flooded)Property damage$1.6 billion USD

Fangshan District was the most heavily affected area of Beijing, located in the southwest, which received a record-setting 460 mm (18 in) of rain, while on average the city received 170 mm (6.7 in) during the same period, the highest recorded since 1951. The Juma River flooded its banks and reached a flow rate of 2,500 m3 (88,000 cu ft) per second. A woman in Fangshan reported the river rose 1.3 metres on her home in approximately ten minutes.[4]

At Beijing Capital International Airport, the floods resulted in the cancellation of over 500 flights, stranding 80,000 travellers.[5]