“That’s why many people took the subway, and the tragedy happened,” Guo told Reuters.
Local media said the dead included four residents of the city of Gongyi, located on the banks of the Yellow River like Zhengzhou, following the widespread collapse of homes and structures because of the rains.
People’s Liberation Army has sent more than 5700 soldiers and personnel to help with search and rescue.
The flooding in Henan, also a hub for agricultural and food production, coal and metals as well as heavy industry, is being closely watched for any serious economic disruptions, though the damage appears to be contained so far. Nissan vehicles and iPhones are made by joint-venture companies in the province.
The latest figures from the Chinese government on Thursday estimated the financial damage from the flooding at about 1.2 billion yuan ($252 million).
From Saturday to Tuesday, 617.1 mm of rain fell in Zhengzhou, almost the equivalent of its annual average of 640.8 mm.
The three days of rain matched a level seen only “once in a thousand years”, the Zhengzhou weather bureau said.
Like recent heatwaves in the United States and Canada and extreme flooding seen in western Europe, the rainfall in China was almost certainly linked to global warming, scientists told Reuters.
“Such extreme weather events will likely become more frequent in the future,” said Johnny Chan, a professor of atmospheric science at City University of Hong Kong.
“What is needed is for governments to develop strategies to adapt to such changes,” he added, referring to authorities at city, province and national levels.
Dozens of reservoirs and dams breached danger levels.
Local authorities said the rainfall had caused a 20-metre breach in the Yihetan dam in the city of Luoyang west of Zhengzhou, and that the dam could collapse at any time.
In Zhengzhou itself, the Guojiazui reservoir had been breached but there was no dam failure yet.
Chinese companies, insurers and a state-backed bank said they had offered donations and emergency aid to local governments in Henan amounting to 1.935 billion yuan ($400 million).
Taiwan’s Foxconn, which operates a plant in Zhengzhou assembling iPhones for Apple, said there was no direct impact on the facility.
China’s largest automaker, SAIC Motor, warned of short-term impact on logistics at its plant there, while Japan’s Nissan said production at its factory had been suspended.
Schools and hospitals were marooned and people caught in the floods flocked to shelter in libraries, cinemas and museums.
“We’ve up to 200 people of all ages seeking temporary shelter,” said a staffer surnamed Wang at the Zhengzhou Science and Technology Museum.
“We’ve provided them with instant noodles and hot water. They spent the night in a huge meeting room.”
After the First Affiliated Hospital of Zhengzhou, the city’s largest, lost all power, officials raced to find transport for about 600 critically ill patients.
Karsten Haustein, a research associate at the University of Oxford, said that normal monsoonal activity and the region’s mountainous topography made it “highly susceptible” to such disasters, but the impact was supercharged by climate change. Haustein said that global warming brought an extra 10-20 per cent of rainfall to Henan.
“Climate change isn’t helping to reduce the risk, it rather increases China’s vulnerability to these types of weather extremes,” said Haustein.
The neighbouring province of Hebei issued a storm alert for some cities, including Shijiazhuang, its capital, warning of moderate to heavy rain from Wednesday.
Bloomberg, Reuters, The Washington Post