Situated at Mingsha Hill near the Dunhuang Grottoes, the spring in the shape of a half moon is surrounded by sand dunes but has never filled up with sand for the past 2,000 years.

But over the past four decades, the water level of the spring has continuously declined, from seven to eight meters in the early 1960s to the present two to three meters. And its size has decreased by nearly two thirds.

To stop the drying up, Chinese experts have tried various methods including draining it twice and the construction of an artificial reservoir to replenish the spring with underground water.

However, all these efforts have failed to retain the water in the spring.

Geologist Li Zhengyu with the Dunhuang Research Institute said the water level descent should also be attributed to the changed airflow caused by human activities.

According to him, the spring was part of the Danghe River in ancient times, but after the river changed its course, the spring kept supplying water.

In the early 1970s, to keep out the wind and stabilize the sand dunes, a protective forest was built along a reservoir at the northern foot of Mingsha Hill, which, Li believes, has altered the velocity of the northwest wind and slightly changed its direction.

"In the past, sand in the wind could not drop into the spring directly because the spiraling air current would send it elsewhere. But now, much more sand falls into the spring and sucks away the water," he said.

(Xinhua News Agency April 20, 2003)