Residents wade through floodwaters on a flooded road amid heavy rainfall in Zhengzhou, Henan province, China July 20, 2021. At least 25 people have died in China's Henan province after three days of rain matched what one weather bureau said was a level seen only "once in a thousand years." China Daily via REUTERS

A traffic police officer guides residents to cross a flooded road with a rope during heavy rainfall in Zhengzhou, Henan province, China July 20, 2021. State media reported several people drowned inside a flooded subway tunnel in the provincial capital of Zhengzhou, where more than 500 were pulled to safety. China Daily via REUTERS

A resident wearing a rain cover stands on a flooded road in Zhengzhou, Henan province, China July 20, 2021. About 100,000 people have been evacuated in Zhengzhou, a city of 12 million. cnsphoto via REUTERS

A man carrying a woman wades through a flooded road following heavy rainfall in Zhengzhou, Henan province, China July 21, 2021. China Daily via REUTERS

Residents, holding umbrellas amid heavy rainfall, wade through floodwaters on a road in Zhengzhou, Henan province, China July 20, 2021. cnsphoto via REUTERS

An aerial view shows a flooded road section following heavy rainfall in Zhengzhou, Henan province, China July 21, 2021. Picture taken with a drone. China Daily via REUTERS