Lei Xia had safely evacuated long before the flood came in the afternoon of July 16, and avoided heavy property loss as she also took her furniture and electric appliances with her.

"At about 3 o'clock that afternoon, a sudden rolling sound of gongs signaled the coming flood, which bought time for us to relocate," recalled Lei, who owns a teahouse in Kaizhou District, southwest China's Chongqing Municipality.

Since July 15, torrential rainfall battered the upper reaches of the Yangtze River where Kaizhou is located. Local village and town staff took turns to keep watch and patrol, most of whom with a gong in hand to beat at the first sign of danger.

Gongs, which have been used since ancient times, still play an important role in flood control in rural China, saving people's lives and property.

"Aggressive floods sometimes come at midnight or during the wee hours, and people know it's coming when they hear the beating of gongs," said Zou Pinsheng, a town chief in Kaizhou.

Besides the gongs, loudspeakers also proved effective in issuing emergency warnings.

In Tianba Township of Chongqing's Wuxi County, the flood overflowed a river and rushed to the town at around 3 a.m. on July 16.

"Get up and get out of the house! A flood is coming," screamed town staff Yuan Zhujun on his loudspeaker.

People were stirred from their dreams by his cries and began to move. More than 1,000 residents had been evacuated within three hours when the water level in town reached two meters, with no casualties reported.

"Compared with door-to-door warnings, using a loudspeaker can warn many more residents, thus buying time to evacuate," Yuan said.

Yet in vast rural areas across China, grassroots workers still need to travel step by step around villages and knock on doors at the drop of a hat, especially in those areas mainly inhabited by the elderly who have poor hearing and move slowly.

Fu Shanxiang, Party secretary of the Xianglushan community in Chongqing's Wanzhou District, was still going from door to door after most residents had been evacuated on the morning of June 16.

He found a rope, tied one end to a roadside tree and the other to his waist, jumped into the waist-deep torrent and waded toward an old man and a mother and daughter crying for help across the street on the second floor of a residential building.

The three stranded by the deluge were saved.

"Knocking on every door is a must, and we'll never let anyone get stuck at home, especially the elderly," Fu said.

Drones, intelligent patrol systems as well as other smart technologies have been used to support China's flood control efforts, while ancient methods handed down for generations, like beating gongs, remain important in underdeveloped rural areas of the country.

"Flood control, after all, relies on people," Zou Pinsheng said. "And these old ways will never become obsolete."