It will take approximately 50 years to rehabilitate nearly 2 million square kilometres of eroded land under fundamental control, Chen Lei, vice-minister of water resources, said yesterday in Beijing.

The survey stated "various erosion have affected 3.56 million square kilometres of land or 37 per cent of China's territory."

During the past decade, China's total water and soil eroded land has been reduced to 110,000 square kilometres from 3.67 million square kilometres in 1990.

However, Chen made it clear "it will take nearly half a century for China to control the eroded land and rehabilitate their damaged ecosystems in accordance with China's present erosion-control capabilities."

China has, since 1998, been capable of rehabilitating some 50,000 square kilometres of eroded land annually through building terraces and irrigation systems, stopping farming on hills with a gradient of more than 25 degrees and turning the areas into woodland or grassland.

While raising public awareness of the seriousness of erosion, Chen was confident the result of the survey can help decision-makers update the overall plan for intensifying China's efforts to accelerate erosion-control and rehabilitate ecosystems in eroded areas.

Of the existing eroded land, 1.65 million square kilometres is affected by water, 1.91 million square kilometres by wind, and the rest affected by glaciers and gravity, Chen quoted the second national survey on China's water and soil erosion as saying.

Water and soil erosion has been observed in China by using remote sensing, including mountains, hills and rural and urban areas with different characteristics and weathering, the survey indicated.

Most erosion occurs in southwestern and central China upstream of the Yangtze River - including Yunnan, Guizhou, Sichuan and Hubei provinces, as well as Chongqing Municipality - and northwestern China's provinces and autonomous regions along the middle reaches of the Yellow River, such as Shaanxi, Shanxi, Gansu, Inner Mongolia and Ningxia.

Erosion is creeping across China east to west.

There are 90,000 square kilometres of water eroded land in East China. However, areas eroded by water have amounted to 490,000 square kilometres in Central China and totals more than 1 million square kilometres in the western region due to their fragile and worsening ecosystems.

Northwest China is the worst area plagued by wind erosion, in particular the Xinjiang Uygur and the Inner Mongolia autonomous regions, plus Gansu and Qinghai provinces.

Areas affected by water and wind erosion totals 260,000 square kilometres, found mainly along the Great Wall and western China's Xinjiang, due to drought, overgrazing, overlogging and over reclamation.

(China Daily January 22, 2002)