Kumtag, the country's sixth largest desert, is expanding by 1-4 m eastward every year, posing a threat to the Mogao Grottoes, also known as the Caves of One Thousand Buddhas, in Northwest China's Gansu Province.

One floating dune is only 5 km away from Dunhuang city, home of the grottoes, said Gao Hua, head of the city's tourism administration.

A scientific research group has just concluded the first comprehensive environmental survey of the desert, which appears to be expanding in all directions, posing a direct threat to local grasslands, oases, nature reserves and the caves, which are a UNESCO-listed world heritage site.

Fifteen scientists spent two weeks trekking across the desert to collect geological data and research the hydrology, soil conditions, vegetation and environment in the area.

Wang Jihe, head of the Gansu Desertification Prevention Bureau and a member of the research group, told Xinhua the desert occupies 2,500 sq km between Lop Nur, in Northwest China's Xinjiang Uygur Autonomous Region, and Dunhuang city.

Kumtag's means "sand hill" in Uygur language. As its name suggests, it overhangs the small oasis in Dunhuang, which has nurtured ancient cultures dating back to AD 336 in the arid region.

Data from the Gansu provincial forestry bureau shows that the desert devours 6.7 sq km of arable land every year in Nanhu County, on the edge of Dunhuang.

Dunhuang occupies 31,200 sq km, of which 90 percent has surrendered to desertification.

Funds have been appropriated by the central and local governments to pay for reforestation and desert control efforts to protect the ancient heritage site.

However, progress has been slow compared to the rapid pace of ecological degradation. The research is seen as part of the integrated effort to curb the desertification.

The Mogao Grottoes, one of China's most popular tourist destinations, were listed as a world heritage site by UNESCO in 1987. Altogether, 735 caves have been found, and frescos on the inside walls cover an area of 45,000 sq m. The caves also hold 2,400 colored Buddha statues.

(Xinhua News Agency/China Daily October 9, 2007)