Nearly two dozen people were missing after Tuesday's landslide amid heavy rains [Reuters]

A landslide in southern China has left 21 people missing, further adding to the misery of a nation reeling under the worst floods in a decade following heavy rains.

Rescuers searched for the missing people after a landslide hit Hanyuan county in the southern province of Sichuan on Tuesday morning, the official Xinhua news agency said.

Nearly 60 houses were buried in rocks and mud, and about 4,000 villagers were forced to flee their homes.

More heavy rains are expected for the southeast, southwest and northeast parts of the country through Thursday.

Massive losses

This year alone floods have killed at least 823 people, with 437 missing, and have caused tens of billions of dollars in damage, the State Flood Control and Drought Prevention reported.

Rescuers were searching for 21 missing people as thousands more fled their homes [AFP]

It said two dozen major rivers had risen beyond their warning levels, with workers scrambling to sandbag riverbanks along the Yellow, Jialing, Han, Huai and Yangtze rivers to prevent further flooding.

The water level downstream on the Jialing river in Chongqing breached government warning levels and flooded riverside communities for the second time this week.

Though China experiences heavy rains every summer, flooding this year is the worst in more than a decade, as the flood-prone Yangtze River Basin has seen 15 per cent more rains than in an average year, Duan Yihong, director of the National Meteorological Centre, said in an interview on Wednesday posted on the Xinhua website.

"Rains should begin to slow down in August, but it is hard to predict now what exactly will happen," Duan said. "We have to be vigilant and closely monitor the weather ... do a better job of forecasting."

Dams tested

Record-high water levels have put the capacity of China's massive Three Gorges Dam – the world's largest hydroelectric project which was also built to end centuries of flooding along the Yangtze River basin – to the test.

China's dams have come under pressure as water levels continue to rise [Reuters]

The dam's water flow reached 56,000 cubic metres per second on Wednesday morning, the biggest peak flow this year with the water level reaching 158 metres, Xinhua said, about 10 per cent less than the dam's maximum capacity.

Shipping traffic was suspended at the dam for the second time this month, Xinhua said.

Chinese officials for years have boasted the dam could withstand floods so severe they come only once every 10,000 years.

Flooding this year has overwhelmed reservoirs, swamped towns and cities, and caused landslides that have smothered communities, including toppling 680,000 houses, Xinhua said.

Source: Agencies