A landslide caused by rains in southern China left 21 people missing on Tuesday, adding to a growing death toll from China’s worst flood season in a decade, which is expected to worsen with heavy rains forecast across the country.

Rescuers searched for 21 people missing after a landslide in Hanyuan County in China’s southern province of Sichuan on Tuesday morning, the official Xinhua News Agency reported. Rocks and mud buried 58 homes and about 4,000 villagers were evacuated from their homes.

Floods this year have already killed at least 823 people, left 437 missing and caused tens of billions of dollars in damage, the State Flood Control and Drought Prevention reported.

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 report said. Water levels along the middle reaches of the Huai River, notorious for flooding, were 5 feet (1.5 meters) above its warning level in the provinces of Anhui and Henan.

Three—quarters of China’s provinces have been plagued by flooding and 25 rivers have seen record—high water levels, the Flood Prevention Agency said. The overall damage totalled 154.1 billion yuan ($22 billion).

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

The water level in the massive Three Gorges Dam, the world’s largest hydroelectric project which was also built to end centuries of floods along the Yangtze River basin, hit its highest level ever last week.

Shipping traffic was suspended at the dam for the second time this month, as water levels rose following heavy rains in the upper reaches of the Yangtze, Xinhua News Agency said. About 100 ships were waiting on either side of the dam, where water flow was expected to peak sometime on Wednesday.

More torrential rains are expected for the southwest, southeast and north-eastern parts of the country through Wednesday, the National Meteorological Centre said.

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