The water level in China's largest saltwater lake has risen for five consecutive years thanks to increased rainfall, experts in the northwestern Qinghai Province said Wednesday.

The level of Qinghai Lake rose by 17 cm year-on-year to reach 3,193.5 meters above sea level at the end of December, said Li Yan, an engineer with the Qinghai Provincial Hydrographic and Water Resources Survey Bureau.

At the end of the rainy season in October, the water level measured almost 3,194 meters, she said.

The level has risen for five years since 2005, a record rate of recovery since the bureau was founded in 1955, she said. "It has risen by 70 cm in total in the past five years."

The previous two apparent rises were reported in 1967-68 and 1988-89, she said.

The Qinghai Lake, at the northeastern part of the Qinghai-Tibet Plateau, is China's largest inland and saltwater lake. It shrank by 3.7 meters between the 1950s and 2004, an average 7 cm annually.

Dai Sheng, from the provincial climate research center, said the latest rise was mainly a result of ample rainfall that swelled the lake and reduced evaporation.

Qinghai Province reported an average annual rainfall of 431 mm from 2005 to 2008, Dai said.

Last year, its rain volume totaled 416 mm, compared with 396 mm in 2008, he said.

Meanwhile, the massive forestation program that started in 2002 also helped restore the lake, said Li Yan.

Li and her colleagues were uncertain whether the water level will continue to rise, though meteorological experts believe the lake area will get enough rain water in 20 years to come.

"We predict ample rain in the lake area in the next two decades," said Dai Sheng from the climate research center of Qinghai. "By 2030, the lake will rise by at least 3 meters to become what it was like in the 1970s."

He said global warming and glacier retreat on the Qinghai-Tibet Plateau would also help expand the lake.

The temperature in Tibet Autonomous Region has risen by an average of 0.32 degrees Celsius every 10 years from 1961 to 2008, according to the most recent data available from the China Meteorological Administration (CMA).