Thirteen years after construction began on the Three Gorges Dam on China's biggest river, work on the project often compared to the Great Wall in its scale is nearly complete.

The first pickaxe fell in 1993, when access roads were built to the site on the 6,360-kilometer-long (3,940-mile) Yangtze River that runs from the Himalayan plateau in Tibet to the East China Sea near Shanghai.

"We are going to finish one year early. At the end of 2008, it will be completed," said Huang Hongyong, an official in charge of the project, as he proudly gestured towards the 2.3-kilometer length of the dam.

Besides generating massive hydroelectricity, the dam has been designed to control the flooding that has through the ages repeatedly laid waste to farms, towns and cities along the middle reaches of the river.

"The first goal of this dam was flood control," explained Qin Xixiang, assistant chief engineer of the China Yangtze Three Gorges Project Corporation, which owns the dam.

"Before, we might statistically suffer a flood every 10 years. Now, it will be every 100 years," said Qin.

And if the construction of the gorge has required the huge evacuation of 1.13 million people, supporters of the project argue that it is for the protection of 15 million others.

In this rather dry period, the central spillway, flanked by the two sets of turbines and giant generators, is quiet.

But this tranquility masks the power of the Yangtze, which varies from a flow of 9,000 cubic meters (315,000 cubic feet) per second to 80,000, or even 110,000 per second.

The river is also capable of flooding out tens of thousands of people: 145,000 victims in 1931, 142,000 dead in 1935 and 33,000 in 1954.

This litany of disasters gave rise to the idea of taming the Yangtze quite early on, with Sun Yat-sen, the founder of the Republic of China, first envisaging it in 1918.

But it was not until the start of the 1990s that former premier Li Peng pushed the project through the National People's Congress despite widespread opposition from environmental groups and academics.

China had begun a period of stellar economic growth, was hungry for energy and desperately needed new resources.

The Three Gorges project was originally planned to produce nearly 83 billion kilowatt hours of electricity per year, transmitted over a radius of one thousand kilometers.

On the left bank, 14 sets of 700 megawatt turbine and generator units are already in operation. Next to them is a ship lift, which can hoist vessels of 3,000 tons.

"Ships will be able to sail up to Chongqing (600 kilometers further west) from now on instead of being stranded downstream in the dry season." Qin said.

"Economically, it was vital."

On the right bank, 12 further 700 megawatt units are still under construction and installation.

At the heart of the gorge, workers are busy around the excavations which will accommodate the turbines, each 25 meters in diameter.

About 8,000 people, spread over a wide area, are still working on the project, which at its peak employed 30,000 people.

With a capacity already equivalent to Itaipu, situated on the border of Brazil and Paraguay and currently the largest operating hydro-electric dam in the world, the Three Gorges will eventually overshadow all others.

Between now and the end of the year, a new tender process will be held for adding a new power station with a set of six more 700 megawatt generators, underground and next to that of the right bank.

The dam will hence become "the biggest in the world", according to the China Yangtze Three Gorges Project Corporation.