Water resources around the Sanjiangyuan region -- the source of the Yangtze, Yellow and Lancang rivers -- are dwindling due to the effects of global warming and decreased rainfall, scientists have found.

Locked in the hinterlands of the Qinghai-Tibet Plateau, the area provides 25 percent of the water flowing down the Yangtze River, 49 percent of the water on the Yellow River and 15 percent of the water on the Lancang River. Sanjiangyuan occupies some 360,000 sq m and is considered a key part of the country's riparian resources.

Global warming, in particular, has harmed the water supply in Sanjiangyuan, which was once known as the Chinese water tower, officials with the China Meteorological Administration said.

Much of the rivers' source water comes from melting glaciers and snow, but most of this run-off now evaporates because of the warmer temperatures, experts said.

In addition, the amount of area occupied by glaciers has reportedly shrunk by about a third over the last century.

Given the current amount of rainfall, a temperature increase of 1 C would reduce water flows in the area by as much as 8 percent, experts said.

Since 1961, the temperature in Sanjiangyuan has risen by an average 0.32 C per year, according to official statistics from the China Meteorological Administration. However, the amount of rainfall during the period has declined.

These two factors have caused a variety of problems, including water and soil erosion, desertification and basification, which have seriously affected the local environment and economic development, experts said.

One expert, Qin Dake, has called for more artificial rain operations to reverse the situation.

"Making artificial rain is cheap, efficient and convenient. It can help relieve some of the water scarcity in the area," said Qin.

The authorities have been making rain in the region since last year and have had some success, according to reports.

The Qinghai-Tibet Plateau used to boast 36,000 glaciers covering an area of 50,000 sq km and feeding several of the major rivers in China and Southeast Asia.

(China Daily August 13, 2007)