This year's highest flood crest hit the Yangtze River, China's longest waterway, on Thursday, posing a challenge to flood control and hindering navigation for ships and boats along the river.

An elderly woman observes floodwaters outside her house in Tongnan county, Chongqing, on Thursday. [Chen Chao / China News Service]

The water volume flowing into the Three Gorges Dam increased to 54,500 cubic meters per second on Thursday from 46,000 cu m per second on Wednesday, increasing the dam's water level by 2 meters, according to data released by the China Three Gorges Corporation.

Wang Rujun, director of the Yangtze River Maritime Safety Administration, said the dam will gradually discharge more water to adjust levels in the upper and lower reaches, and the waterway watchdog is preparing to safeguard ship security by issuing an alarm for the coming floods.

According to the latest weather forecast released by the National Meteorological Center, parts of central and eastern China are expected to be hit by continuous rainstorms in the coming week.

Chen Lei, minister of water resources, told a national conference on flood control on Wednesday that with heavy rainfalls expected along the Yangtze, local authorities should minimize damage through the timely release of information and proper adjustment of water discharges in dams and reservoirs.

The Ministry of Land and Resources also warned local authorities to prepare for possible geological disasters triggered by torrential rains before August.

The Ministry of Civil Affairs activated its lowest-level emergency response plan on Thursday to address the floods in Sichuan province, where 13 people died and one was reported missing due to continuous rainstorms since June 29, according to the agency.

The Sichuan provincial civil affairs department said more than 4.6 million people have been affected by downpours in the province, with rainfalls damaging about 37,000 houses.

"Heavy rain affected 52 townships with more than 130,000 people (in Wanyuan city). It inundated two-thirds of the urban areas. Some 70,000 urban residents were relocated. It cut off all the highways, and more than 40 townships were inaccessible," said Cai Shiquan, chief of the emergency response office in Wanyuan of Sichuan.

Deafening sirens were heard on Wednesday as water from the nearby Miaogou River found its way into the city center, rushing into the first floors of houses and covering many cars.

"Fortunately we had moved our valuables to the third floor after we received a government warning about a possible rainstorm several days ago," Yu Longhai, a restaurant owner on the city's Taiping Road, said.

In Tongnan county, Chongqing, nearly 8,000 people living near the Qiongjiang River were evacuated, according to figures from the county's information and press bureau.

The flood submerged trees and buildings in Ciqikou, an ancient town in Chongqing, forcing locals to leave their homes.

Wu Mengyuan, a restaurant owner in Ciqikou, said in her experience, the water will recede within three or four days and then rise again.

According to statistics from the Ministry of Civil Affairs, between the continuous rainfalls since June 20 and the mudslides in Sichuan province since June 29, at least 63 people have been killed and 42 are missing. More than 10 million people have been affected across the country.

Zhou Lihua in Wuhan, Huang Zhiling in Chengdu and Xu Wei in Chongqing contributed to this story.

wangqian@chinadaily.com.cn