China to spend $9.7 bil. to prevent silting up of Yellow River

Asian Economic News, Jan 10, 2005

BEIJING, Jan. 5 Kyodo

China will spend $9.7 billion on tens of thousands of new ''soil dams'' designed to filter sediment out of runoff water bound for the Yellow River, thus preventing flooding in the river's lower reaches, state media and water experts said Wednesday.

Xinhua News Agency said the investment will fund the building of more of these silt retention structures on the Loess Plateau of central China, from which an estimated 1.6 billion tons of sediment flows into the Yellow River annually, as well as the replanting of farms created in the 1970s with trees.

The Xinhua News Agency called the plateau, which has been subject to centuries of deforestation and inappropriate conversion of steeply sloped pasture land to crop cultivation, as well as severe overgrazing, one of the ''the world's worst areas for soil erosion.''

The dams, essentially filters that let water pass but block sediment, will stop surrounding topsoil 100-300 meters deep from filling in the riverbed and raising it higher than surrounding land, said Ma Jun, a senior researcher with Sinosphere Corp., an environmental consulting firm in Beijing.

China began building soil dams around 1980, and the dams are effective for flood control, Ma said, though some criticize them for holding back water when it is needed downstream.

Soil dams are particularly useful when sudden heavy rain storms threaten to flood the river, said Zhu Xiaoyong of the central government's Yellow River Water Conservancy Committee in Henan Province.

Xinhua said the investment will ''improve the living standards'' of 70 million rural residents on the plateau -- which wholly or partially covers Shanxi, Shaanxi and Gansu provinces, and the autonomous region of Inner Mongolia -- but did not specify how.

The report also did not say who would pay or supervise the new projects, but Zhu said such a large investment would need approval from the ministries of forestry and water resources.

The World Bank has over the past decade funded a watershed rehabilitation project in the Loess Plateau to the tune of $300 million. But the project ended last year.

According to a bank report, about 430,000 square kilometers of the 640,000 square-km plateau is subject to severe erosion, resulting in sedimentation and flood water being carried to the lower reaches of the Yellow River, where flooding has resulted in enormous loss in property and human lives in the past.

While floods have in recent years been brought under control through strengthened river embankments and the construction of reservoirs, silt continues to be deposited in the lower reaches and the river bed is rising at a rate of about one meter every 10 years.

In some reaches the river bed is more than 10 meters above the surrounding farm lands, necessitating the costly raising and strengthening of flood protection dikes.