The silting problem has been handled well in the construction of the Three Gorges Dam, according to the Chinese Academy of Engineering.

Following the completion of the dam on Saturday, the Three Gorges Project will begin to fully store water next month and the huge amount of silt washed down into the Yangtze from the upper reaches of the river will be stopped by the gigantic dam and built up in the reservoir.

However, progress has been made to reduce silting in the reservoir through a process of "storing water when it is clear but discharging it when it becomes muddy."

According to Zheng Shouren, a member of the engineering academy, the 23 deep-set spillways in the Three Gorges Dam are used to wash silt when the water level is kept at 145 meters during the flood season.

But in the late period of the flood season when the silt content in the water drops, the water level will rise to 175 meters after the spillways are closed and the water storage begins, Zheng explained.

Latest statistics provided by hydrological departments show more than 600 million tons of silt have been carried down into the Three Gorges Reservoir, of which 200 million tons have been washed downstream to the Three Gorges Dam.

The data demonstrates that 40 percent of the silt in the Three Gorges Reservoir has been swept away via its deep-set spillways, 10 percent higher than the target originally set, said Professor Wang Jun, a Chinese water control specialist.

"Silting is listed by the developers of the Three Gorges Project as one of the major technical problems that they face. A lot of investment has gone into resolving the problem," said Wang.

Zheng Shouren also suggested measures including repeated dredging to keep ports both upstream and downstream functional and the main waterway of the Yangtze from bursting its banks.

However, Dr. Wang Wei with the Yangtze River Flood Control Headquarters values the monitoring of silting more than other Chinese water control specialists.

The level of water stored in the Three Gorges Reservoir will be kept at 156 meters after flood season begins this summer, but when to raise the storage water level to 175 meters should be decided by the law which governs the movement of silting, said Dr. Wang Wei.

Source: Xinhua