The Guangzhou city management authority will install screens in the first half of this year on the 130,000 sewer and drainage pits across the city that are relatively deep or may put a person's life at risk.

Screens, used to prevent passers-by from falling into a manhole, had been installed in 80 percent of such pits by last year, the city management committee of the capital of Guangdong province said at a news conference on March 26.

"We will also require the owners of drainage pits to assign one guard to stand by a pit if it needs to be uncovered to quickly drain off water in heavy rains. The guard is not allowed to leave until he or she places back the cover," said Zhao Hong, deputy director of the city management committee, who added that the measure has proved to be effective during flood seasons in the past few years.

The safety hazard caused by a missing manhole cover has caught public attention since an accident in Changsha, Hunan province, on Friday night when a young woman fell into an uncovered sewer in heavy rain. She is still missing.

More than 1.5 million manhole covers dot Guangzhou and they belong to different government departments including the water authority, electric power bureau and communication agency. A set of regulations on the design and construction of the city's manhole covers went into effect on March 1, offering a unified standard.

Guangzhou is the first city in China to release local regulations on manhole cover construction, according to Wu Huiwen, deputy director of the Guangzhou Bureau of Quality and Technical Supervision.

"The regulations were suited to local conditions. For example, you can see a supplementary provision on the width of cracks of a cover for water to flow in. The provision took the high rainfall in the city into consideration," said Wu.