China is facing considerable flood control challenges, after torrential rains simultaneously raised water levels on the Yellow and the Yangtze rivers, authorities have reported.

Water flow at the Wubu Hydrologic Station in Shaanxi province, for instance, reached 7,580 cubic meters per second at 8 am on Saturday, the second flood peak to hit the middle reaches of the Yellow River this year.

Flowing at the lower reaches of the river, the peak took the water level at the Longmen Hydrologic Station in Yulin above its warning level, the State Flood Control and Drought Relief Headquarters said on Sunday.

And water at Wubu Hydrologic Station was reported to be flowing at a rate of 10,600 cu m per second at 1 pm on Friday, its highest level since 1989.

Some 40,800 residents in Shanxi and Shaanxi provinces had to be relocated on Saturday because of the threat of flooding, the headquarters said.

A section of the 218 National Highway, in Hejing county, the Xinjiang Uygur autonomous region, is severed by floods on early Saturday after continuous rainfall. Gai Niman / Xinhua

On Sunday, the Hukou Waterfall Scenic Area in Shaanxi's Yichuan county reopened to the public, two days after an emergency closure on Friday due to the year's first flood peak to hit the Yellow River.

"Some visitors were allowed back in the morning, but they were not allowed to walk close to the waterfall for safety concerns," said a staff member named Song at the scenic area.

He said water levels at the upper reaches of the Hukou Waterfall are now being monitored full time.

According to China Three Gorges Corp, water was released from the Three Gorges Dam at a rate of 45,100 cu m per second on Sunday in an effort to reduce the flood risk on the upper reaches of the Yangtze.

"But controls will not be eased back any time soon, as rainfall is again expected on upper reaches of the Yangtze," the headquarters said.

On Sunday, part of Jiangxi province's Poyang Lake, China's largest freshwater lake, saw water levels exceed warning levels, as flooding on the upper and middle reaches of the Yangtze raised heights.

The level at the lake's Xingzi Station had risen to 19.01 meters by 8 am on Sunday, its highest in two years, and 1cm above its official warning level, Tan Guoliang, head of the Jiangxi provincial hydrographic bureau, told Xinhua News Agency.

Also affected by rising water on the upper and middle reaches of the Yangtze, levels at the Jiujiang section of the river in Jiangxi had risen to 19.54 meters by 8 am on Sunday, more than a meter higher than six months ago, and the water was still rising, he said.

Meanwhile, train services resumed on the flood-hit Nanjiang Railway in the Xinjiang Uygur autonomous region on Sunday morning.

Five trains operating on the line on Saturday were ordered to stop at the nearest station due to flooding and mudslides unleashed by continuous rain. No casualties were reported, the Urumqi railway bureau said on micro blog on Sunday.

Heavy rains and storms are again expected to hit most areas of the country from Sunday to Tuesday.

During the same period, torrential rain is being forecast specifically for central parts of Heilongjiang province, southeastern parts of Hebei province, and southern parts of Tianjin, bringing precipitation of up to 120 mm in some regions, according to the China Meteorological Administration.

At the other end of the scale, a heat wave is now being forecast for regions along the Yangtze, Huaihe and Hanjiang rivers, as well as Chongqing, with temperatures rising to 38 C from Sunday to Tuesday, it said.

Zheng Guoguang, director of the China Meteorological Administration, urged his department to ensure the accuracy of weather forecasts to minimize the damage brought by changes in the weather in coming days.

Meteorological monitoring in areas especially prone to flood and other weather disasters need to be strengthened, he said.

"North China will face changeable weather conditions in the near future, and the Haihe River basin is likely to see more challenges on flood control," he said at a working conference on Saturday.

"At present, relief work is still continuing in many regions after torrential rains hit in the past few weeks. Therefore, any weather change will have an impact on local relief work," he said.

The State Flood Control and Drought Relief Headquarters has urged its branches in Shanxi, Shaanxi, Gansu, Qinghai, Ningxia and Inner Mongolia to strengthen efforts on flood control.

jinzhu@chinadaily.com.cn