The source water of the Yellow River has dwindled by 23 percent more in the past ten years than the average level in the previous 40 years in northwest China's Qinghai Province, environmental officials said Saturday.

The provincial Water Resource Department has been monitoring the source water and attributed the water changes to environmental degradation at the river head.

The river head area of the Yellow River failed to conserve as much water as before due to a degenerated environment and global climate change, said Han Yongrong, an expert with the department.

Statistics provided by the department show that the average water volume from 1991 to 2002 is about 23 percent less than the average level in the previous 40 years, and the water volume is still dwindling.

In the past two years, Qinghai has observed rich rainfall and some areas even received 40 percent more water than the average in the previous years. But the rich water did not stop the water shrinkage at the river head.

This indicated the soil could not conserve as much water as before, Han said.

"The situation is already severe in the rich water season and will be even worse in the low water season," he said.

Source water for the Yangtze River and Lancang River has dwindled by between 10 percent to 4 percent and 4 percent to 7 percent respectively in the past few years, according to environment officials.

Qinghai in the northeastern Qinghai-Tibet Plateau is the source of Yellow, Yangtze and Lancang rivers, the three major rivers in China.

(Xinhua News Agency March 26, 2005)