The massive Xiaolangdi Reservoir on the upper reaches of the Yellow River, China's second longest waterway, has prevented some 900 million tons of silt flowing to the lower reaches since it started filling in Oct. 1999.
According to a source from the Xiaolangdi reservoir construction administrative bureau, this has greatly relieved the long-time severe build up of silt in the river's lower reaches.
Before 1949, an average 1.6 billion tons of silt flowed through the river every year, raising the level of the riverbed in the lower reaches by 10 centimeters annually and forcing flood embankments to be built along the banks, the source said.
With the passage of time, the Yellow River rose higher than the surrounding countryside and gained the notorious nickname of "the river above ground".
After the People's Republic of China was founded in October 1949, the central government continued to extend and consolidate the original embankments until they were more than 1,300 km long and able to repeatedly resist flood scourges.
However, the build up of silt in the river's lower reaches was still severe, with 400 million tons filling up the riverbed every year.
The Xiaolangdi reservoir was designed to hold 12.65 billion cubic meters of water and 7.6 billion cubic meters of silt, said Liao Yiwei, deputy director of the Yellow River Water Resources Committee. When the reservoir was full, its dam would block up to 10 billion tons of silt so that the riverbed level in the lower reaches would stabilize for the next 20 years.
(Xinhua News Agency February 10, 2003)