The headquarters for Flood Control on the Yellow River, China's second longest, announced yesterday that it would start to clear away sediment in the lower reaches of the world's muddiest river on June 16.
It will be the fourth clearing stunt of the kind designed to lower the bed of the river.
The flood-prone Yellow River is the most heavily silted in the world. It was known as "China's sorrows" for the heavy losses caused in floods. For centuries, the Chinese have been battling hard to harness the river.
Every year, the river carries 1.6 billion tons of silt into the lower reaches, depositing 400 million tons. For about 800 kilometers in the lower reaches, the watercourse is four to six meters higher above ground level, threatening communities and livelihoods.
Severe soil erosion from the Loess Plateau, where the upper reaches of the Yellow River traverses, has accumulated at the lower reaches of the river, elevating the riverbed by annual rate of 0.1 meters.
Experts, who reckon that a satisfactory ratio between the water and sediment will improve dredging, have contrived to create floods to brush away silt deposited on the riverbed at the lower reaches of the river.
A spokesman with the headquarters was confident of a successful clearing mission as enough water has been stored for the purpose this year. Up to now, eight reservoirs on the upper and middle reaches of the river have kept about 22.7 billion cubic meters of water altogether, 700 million cubic meters more than that for the same period last year.
The headquarters has worked out a detailed plan regarding silt clearing, and the three reservoirs of Wanjiazhai, Sanmenxia and Xiaolangdi, all on the middle reaches of the Yellow River, are expected to play a leading role in the silt clearing task.
A total of 260 million tons of silt have been washed out into the sea via the flooding experiments since 2002 when China began to clear silt and lower the bed of the river at its lower reaches with a series of artificial flooding experiments.
Up to now, the lower reaches of the Yellow River are now capable of accommodating a water flow of 3,000 cubic meters per second, compared to 2,000 cubic meters per second before the experiments were carried out.