The Three Gorges Dam, the world's largest hydropower project, has reached its shipping capacity and already exceeds the target set for 2030, the Ministry of Transport said.
One of the key benefits of the vast infrastructure project was an increase in shipping capacity, but now engineers are struggling with the challenge of how to provide more room for cargo on the Yangtze River.
The dam has made the river deeper and slower, allowing for easier navigation - especially upstream - for cargo and passenger vessels. The limiting factor for cargo, however, is the capacity of a five-step lock and a soon-to-be-completed ship lift to transport vessels across the 181-metre high dam.
"We estimate the throughput of the five-tier ship lock of the Three Gorges Dam will hit 110 million tonnes this year … It's far beyond our expectations," Li Yang, deputy director of the Policy Research of Ministry of Transport, said at a press conference in Beijing yesterday. "The shipping capacity of the three Gorges Dam's lock is already full."
Li said the project was designed in the 1980s when experts estimated that less than 100 million tonnes of shipping would use the scheme each year before 2030.
The tonnage of shipping using the five-tier lock exceeded 100 million for the first time in 2011, more than five times the level before the dam was constructed.
It reached a record high of 100.06 million tonnes last year, representing 40,848 cargo vessels and 2,461 passenger ships, or 300,000 tonnes per day.
"The transport department has tried its best to improve and increase the shipping capacity [of the Three Gorges Dam]. But we found the potential is limited," Li said. "Now the five-tier lock of the Three Gorges Dam is in full operation … 24 hours a day on more than 355 days a year."
In normal conditions, ships need to wait an average of 40 hours to get through the locks. It takes longer during fog, floods or maintenance shutdowns.
Li said a new ship lift would be completed by July next year.
"But the lift's annual throughput capacity of cargo will be just 6 million tonnes," he added.
The Three Gorges office of the State Council was also researching new capacity, Li said.
The river is the leading means to transport cargo in the mountainous Three Gorges area.
Construction of the project, which cost more than 248 billion yuan (HK$312 billion), began in December 1994. It consists of a dam and a five-tier ship lock, and 34 generators with a combined capacity of 22.5 gigawatts. The world's next biggest power plant, the Itaipu dam shared by Brazil and Paraguay, produces 14GW.
As well as producing electricity, the dam is intended to reduce flooding downstream by providing a huge reservoir to store excess water. Some 1.4 million people were relocated to make way for the project.
The dam has been controversial both domestically and abroad. Beijing regards the project as a historic engineering, social and economic success but critics say the dam has done great damage to the environment.
Professor Zhang Boting , deputy secretary general with the China Society for Hydropower Engineering, said the traffic congestion at the Three Gorges was good news to him.
The dam's construction considerably increased water depth in some dangerously shallow sections, allowing large cargo ships to pass. It also reduced the river's flowing speed, making upstream navigation easier.
"Some shipping companies save up to 70 per cent of fuel after the dam was built. That's a big boon to the whole shipping business," he said. But the traffic jam at the lock was giving the government a mounting headache and it did not have a cheap or easy remedy, Zhang said.