A massive project to divert water from China's south to its drought-prone north -- which has seen hundreds of thousands of people relocated -- will become partly operational next year, state media reported.

The South-North Water Diversion Project is one of the country's largest infrastructure projects since the building of the Three Gorges Dam, which involved the relocation of more than one million people.

Sun Yifu, deputy water resources chief in the eastern province of Shandong -- who is also involved in the programme -- said his province's part of the project would be completed at the end of the year, the Xinhua news agency said.

He added that "the entire project" would become operational in the first half of 2013, and start supplying water to arid parts of the north, the report said late Saturday.

China's South-North Water Diversion project consists of three routes -- the eastern, middle and western routes -- and Sun was referring to the eastern portion of the project, or a 1,890-kilometre (1,170-mile) canal.

Construction on the 1,430-kilometre central route began in 2003 and will only be operational in 2014. The western section, meanwhile, has yet to see the light of day.

Chinese revolutionary leader Mao Zedong is credited with coming up with the idea for the massive diversion programme, which will feature a tunnel dug beneath the Yellow River -- the second-largest in China.

But the project -- which will cost an estimated 500 billion yuan ($79 billion) -- was only approved in 2002.

Critics say it could be a huge waste of resources that risks creating new water shortages and sparking environmental disasters. They also point to the human cost of mass relocations to make way for the canals.