Located in the central province of Hubei at the place where the Yangtse River leaves the spectacular and legendary landscape of the Three Gorges and spills onto the central plain of China, the dam is a concrete colossus over 100 meters (320 feet) high which took nearly 10 years to build.

On Sunday, valves will be closed to allow the water level to rise 65 meters in two weeks time to a height of 135 meters, creating a reservoir 436 kilometers (273 miles).

It will swamp 13 rural cities, once home to some 724,000 people now displaced to new homes above the high water mark, or sometimes as far Shanghai or Guangdong province.

Because of China's Severe Acute Respiratory Syndrome (SARS) outbreak -- and perhaps the stepping down in March of former Prime Minister and principal backer of the project Li Peng -- no significant ceremony will mark the event. But writer and dissident Dai Qing, a long term critic of the project, suggested another reason.

"The funds for this project (24.5 billion dollars) have already been collected. That is why leaders today prefer not to speak."

Moreover, he said: "They do not want to answer questions that might be raised, questions about pollution of the reservoir, about cracks that have appeared in the dam itself and questions about the solidity of its foundations."

More serious, sedimentation of the reservoir -- against which the dam's engineers say they have taken the necessary precautions but which independent specialists have labelled as inadequate -- has called into question the ability of the dam top stop flooding from the Yangste which has killed tens of thousands of people throughout the 20th century.

"There are many alternatives for flood control that would bring greater benefits all around and would be far less costly in economic and environmental terms," said Paul Harris, specialist in environmental issues at the University of Hong Kong.

But regarding the generation of electricity, production of which will reach about 84.7 billion kilowatt hours annually beginning from 2009, Harris is more supportive.

"This will be important for China's development and, from national and even global perspectives, has benefits in that the energy produced will not contribute to global warming," he said.

Bill Mok, utilities analyst with the ING investment bank in Hong Kong, agreed.

"The Three Gorges Dam makes sense in terms of (meeting) electricity demand growth, as well as for the diversification of energy sources'" he said.

Already, the builders of the dam are looking to other projects -- the Three Gorges Project Development Corporation announced this week plans for four more dams in Jinshajiang, higher up on the Yangtse, over the next 20 years.

Together, these projects will produce twice the electricity of the Three Gorges dam, but Dai Qing said that energy conservation is a better solution to China's energy problems and that he will continue his battle against power-generating dams.

"Although the (Three Gorges) dam has already been built, we will continue to oppose its use," he said, citing the dynamiting of certain projects in Europe and the United States.

"In wanting to subdue nature, to bring in under control, one will only succeed in destroying the framework of life," he said.

SPACE.WIRE