Four silt-stirring vessels started operation Saturday morning at the end of the Xiaolangdi Water Control Project, signifying the commencement of China's third-round sand-washing operation to clear up the course of the sediment-laden Yellow River.

The operation, which will take 24 days to complete, will become a landmark for China to shift from the traditional to modern means to harness and explore its second longest river, according to Li Guoying, director of the Yellow River Water Resources Committee.

The committee organized sand-washing operations in July 2002 and September 2003 by discharging speeding currents from the Xiaolangdi project on the lower reaches of the river, successfully sending 187.1 million tons of sand into the sea.

The third-round operation will rush off the water stored at the Wanjiazhai and Sanmen Gorge reservoirs in the middle reaches of the Yellow River and at the Xiaolangdi project, with the aids of engineering methods to churn the densely-silted river sections and the sediment of the Xiaolangdi reservoir, so as to scour almost the river and expand the runoff of its lower reaches, according to Li Guoying.

The largest of its kind on the Yellow River, the Xiaolangdi project is China's second only to the Three Gorges Dam on the Yangtze in terms of workload.

The project had prevented some 900 million tons of silt from flowing to the lower reaches since it started storing water in October 1999.

However, the build-up of silt in the lower reaches of the river was still serious, with 400 million tons silting up on the riverbed to raise its water level by 10 centimeters every year.

The silt has built up a new riverbed, known as the "second hanging river" by the locals, on top of the original riverbed on the lower reaches from Kaifeng, central China's Henan Province, to the mouth.

The second largest river of China, the 5,464-km-long Yellow River originates in the Qinghai-Tibet Plateau, winds its way through eight provinces and autonomous regions, and empties into the Bohai Sea in north China.

Once a notorious troublemaker in the Chinese history, the Yellow River used to breach its embankment twice in three years and change its course every 100 years over the past 2,000 years.

Now the Yellow River carries some 1.6 billion tons of silt into the sea annually.

(Xinhua News Agency June 19, 2004)