Chinese scientists have been fighting against nature and man to protect the renowned frescos at Dunhuang grottoes from damages in the tough climate of northwest China.

The Mogao Grottoes in Dunhuang city contain some 2,000 clay sculptures and more than 45,000 meters of mural paintings that date back from the 5th to the 14th centuries. The grottoes are also known as "Caves of the Thousand Buddhas" and are one of the world's most vital sites of ancient Buddhist culture.

But the site, surrounded by deserts and Gobi, are constantly harassed by the dry weather, strong gales and sand storms that threaten the grottoes and the heritage inside.

China started to protect the grottoes from wind and sand in 1944. Since 1990, the country has carried out several tests, introduced state-of-the-art technologies and joined hands with international organizations to curb sand storms in the region.

"We can say for certain the efforts have started to pay off," said Wang Wanfu, deputy head of the Dunhuang Research Institute.

According to Wang, sand that accumulates in the grottoes today is less than 10 percent of what was reported in the 1980s. "We used to clean out 3,000 to 4,000 cubic meters of sand from the grottoes a year before the 1980s," he said. "Now it's about 100 cubic meters."

Over 30 leading sand control experts gathered in Dunhuang last November to discuss ways of harnessing sandstorms from their roots and to map out a long-term scheme for the protection of the grottoes.

Since the 1980s, the Dunhuang academy has also joined hands with international research bodies to monitor the local geological and meteorological environment in the area as well as the temperature and humidity inside the caves.

In addition to the erosions of wind and sand, experts say damages to the grottoes have also stemmed from the modern perils of mass tourism, where the moisture from the breath of visiting crowds can impair delicate murals that have survived for centuries in an arid desert climate.

"One simple example, the colors of the murals may fade when the carbon dioxide and moisture the visitors exhaled reach a certain density in the caves, which are often small and narrow," explained Li Zuixiong, vice president of Dunhuang Research Institute.

Nearly 4 million tourists from more than 80 countries and regions have visited the grottoes since the first one was opened to visitors in 1979.

The 50 grottoes that open to tourists today are receiving more than 300,000 people a year, a figure that is expected to climb to 500,000 in the coming five to ten years.

To minimize damage to the grottoes, Li's organization diverted the tourists to eight different routes in 2000. Last year, the organization requested tourists to make reservations beforehand in an effort to adjust visitors' flows.

In the meantime, scientists are working on a virtual caves project, which will allow viewers, without entering the grottoes, to feel like they are visiting the real grottoes of amazing Buddhist art.

Use of digital means and other high technologies will also help conserve the cultural heritage, including its Buddhist manuscripts, painted scrolls and other historical documents, according to Li.

The grand grottoes that made the remote Dunhuang city on the ancient Silk Road famous were included in the world cultural heritage list of the United Nations Education, Science and Culture Organization in 1987.

Of the 735 caves, 492 still more or less remained intact. All have been subjected to various kinds of damage or indignities to some extent, from the long-term erosion of wind and water, to the smoke from fires built by bivouacked troops, according to experts.

(Xinhua News Agency June 28, 2004)