POYANG LAKE: Normally surrounded by water in August, a pagoda-topped island in China's Poyang Lake is now fully visible, testifying to the dramatic impact of a long drought and heatwave on a vital part of the country's irrigation infrastructure.

China's biggest freshwater lake, Poyang is known as the "kidney" because of the role it plays in regulating the flow of the Yangtze river in central Jiangxi province, taking on floodwaters in the normally wet summer and then receding dramatically during the dry autumn and winter.

This year, as a record heatwave throughout the Yangtze basin stretches beyond 70 days, the lake has shrunk far earlier than usual and is just a fifth of its size of a few months ago. 

Locals say they've never seen anything like it.

"Last year there was water in the lake," said 57-year old Zhang Daxian, who makes his living there. "This year I don't know what happened. It is so dry."

Poyang's hydrological functions have also been eroded over the years by sand mining and the construction of the Three Gorges and other large-scale dams upstream.

Authorities have proposed building a large sluice gate to exert more control over water flows - a move criticised by green groups.

Zhang, a Buddhist, is paid 1,000 yuan ($146) a month by the local government to clean on the island, known as Luoxing Pier, when water levels drop, a job usually required for half the year.

"This year it's been dry for ... almost two months. The water was supposed to recede in the middle of September, but this year... it dried up in the middle of July," he said.

On Wednesday, residents were able to walk comfortably on the cracked and baked flats of the lake on Wednesday, treading through dead mussels and fish - though some took it in their stride.

"It is just climate change," said Zhang, a 51-year-old whoused to work for the local fishery administration. "It happens. It is normal."

Fishing was banned on Poyang Lake in 2020.

The shrinkage has also affected shipping and drinking water supplies for nearby communities. Authorities have already released water from the Three Gorges and Danjiangkou reservoirs to alleviate downstream shortages, state broadcaster CCTV said on Tuesday.

Du Lei, an engineer with the remote sensing centre of the Ministry of Natural Resources, told CCTV that the lake was still receding, and some of its small feeder rivers had completely dried up.

"The entire northern part of the lake is more like a river because of the shrinking of the lake's surface," he said.