After four years of dumping rock and stones into the rushing waters on each side of the Yangtze river near the city of Yichang, Chinese engineers will today attempt to close the final gap of 40 metres and start the second phase of the construction of the world's biggest hydro-electric dam.
Watching a rehearsal last week, when the two walls of the 1,140 km-long barrier were still 40 metres apart, it was clear that the epic operation to conquer the Yangtze just below the scenic Three Gorges will almost certainly succeed.
US-made Caterpillar dump trucks with massive tyres raced to the breach from each end at the rate of one a minute, dumping their rocky burdens with a roar and driving away in clouds of dust with the rear still tipped up.
They sped down a 45-degree slope into one of the biggest manmade holes in the world, gouged out of gray rock, where they were reloaded in seconds by Japanese Komatsu diggers and Koreanmade Daewoo excavators, working like over-achieving dinosaurs.
From today the Yangtze, the world's third biggest river, will flow through a narrow purposebuilt channel while work proceeds on the giant dam, which will eventually create a reservoir 600 km long, holding 39.3 billion cubic metres of water.
The 185 metre-high dam is intended to end thousands of years of calamitous flooding in the lower reaches of the Yangtze, which rises in Tibet and flows into the East China Sea at Shanghai. This century alone the Yangtze has claimed 314,000 lives.
It will also still the turbulent waters of the Three Gorges which for centuries have rushed through its steep defiles, making river journeys hazardous.
The water will now rise from 78 to 135 metres above sea level by 2003, at which point 14 turbines will begin to generate power, and a further 40 metres by 2009.
Mammoth structures are rising at the dam site, including a 250 metre-long ship lock and a 40 storey-high elevator which will lift passenger and cargo boats of 3,000 tons in 45 minutes.
Chinese officials proudly tell visitors that the dam, which will cost 200 billion yuan (£17 billion) will be the greatest man-made artifact in the world since the Great Wall. Already school children are being brought in buses to a conical observation tower on high ground to gaze in awe at the work in progress.
Several sculptors were working flat out last week on socialist-realism carvings around the tower to have it ready for today's expected arrival of the Prime Minister, Mr Li Peng, a Soviet-trained engineer, to witness the first triumph of the project he has championed.
Today's damming "is an event that not only inspires people but demonstrates the greatness of the achievement of China's development," said Mr Li. From the view-point tourists see a banner proclaiming "Build the Three Gorges, Pride of the Chinese. Raise High the banner of Deng Xiaoping Theory. Move Bravely Forward."
"A lot of people will lose their homes, but it is good that the big floods will come to an end and that there will be electricity for making China a modern country," said a teacher with a class of 10year-old girls, who were more interested in cheerfully trying out their classroom English on a foreigner, with a chorus of "Good morning".
The world-record statistics of the dam are matched by the human cost. Over 1.2 million people will be forced to move from their homes in two cities, 140 towns and 4,500 villages along the banks of the Yangtze. Already 53,000 people and 100 factories on the low-lying areas have moved to higher ground.
Villagers affected have adopted a fatalistic attitude, as arguments about a dam have raged since it was first proposed by Sun Yat-sen, the father of modern China, in 1919. It was given the go ahead by the People's Congress in 1992 though a record one-third of deputies refused to endorse it.
The dam's critics fear that it will become an ecological disaster, trapping silt and effluent and turning the reservoir into a swamp in less than a century. There are concerns about earthquakes caused by the weight of water, a catastrophe due to a military attack, landslides, and the loss of arable land, rare flora and fauna, and cultural relics. Its most outspoken Chinese opponent Dai Qing argues in a book she cowrote in 1989 - banned in China - that the real number of dislocated people will be almost two million. "It is not an engineering project but a disaster project," she says.
The Chinese Academy of Sciences lists the main benefits as (1): the end of massive flooding, even in the case of a millennial disastrous flood such as in 1870; (2) the generation of 84.68 terawatt-hours (one terawatt equals a trillion watts) of clean electricity, equivalent to the output of 15 polluting coal-powered stations; and (3) vastly improved navigation up to the city of Chongqing, the world's third largest city, situated at the upper end of the planned reservoir.
It maintains that the silt problem can be overcome by sluicing muddy water out during the rainy season, helped by cascade dams which will reduce sediment in Yangtze tributaries.
The dam has also brought investment to a poor area of China and provided work for 18,000 men and 18,000 temporary workers. The Three Gorges dam is China's most ambitious remodelling of nature, though the Communist government already has a long record of moving populations around to create dams and hydroelectricity. Since 1949 it has built 80,000 reservoirs and dislocated 10 million people.
See: Weekend 1