XI'AN, July 27 (Xinhua) -- China's largest desert lake - Hongjiannao - is still shrinking as a result of climate change and human activities, and may vanish in a few decades, experts have warned.

    "Just 10 years ago, one couldn't see the other bank of the Hongjiannao even through a telescope. Today, it's visible with the naked eye," He Fenqi, a researcher with the Chinese Academy of Sciences, said at an international seminar on wetland preservation over the weekend in Shenmu County of northwest China's Shaanxi Province.

    The Hongjiannao, sandwiched between the Muus Desert in Shaanxi Province and the Erdos Plateau in north China's Inner Mongolia Autonomous Region, has shrunk by at least 30 percent in the past two decades.

    Its lake area, which measured more than 6,600 hectares in the 1990s, has shrunk to 4,600 hectares, and its water level is declining by 20 centimeters annually.

    Geological data shows the water source for the lake is mainly ground water whose level in the past decade has continued to fall and a number of bogs and small lakes around Hongjiannao have disappeared.

    "Unless adequate measures are taken, Hongjiannao itself may vanish in a few decades, just like the Lop Nur in the northwestern Xinjiang

    Uygur Autonomous Region," said Chen Kelin, China director of Wetlands International NGO.

    The Lop Nur was the largest lake in northwestern China before it dried up in 1972 as a result of desertification and environmental degradation.

    Yang Fengming, deputy director of the Hongjiannao scenic spot's administrative committee, said dams had been built since 2006 on two of the total seven rivers that drained into the lake to improve water conservation facilities in the upper stream.

    "This has cut off water supplies to the lake. In the long run, encroaching desert will dry up the lake and destroy the habitat of more than 20 species of rare birds," said Yang, who was born and brought up in the lake area and has seen how it has shrunk in recent years.

    He said the committee has banned tourists and pleasure boats from approaching the birds' habitat.

    "We have forestry workers on patrol in the lake area and regularly feed the birds," he said.

    Besides the shortage of water supplies, the Hongjiannao is also affected by industrial pollution from coal-fired power plants and coal mines, the nearest less than 3 kilometers from the lake.

    "We should set up a national level nature reserve in the area to better protect the wetlands," said Chen Kelin. "We cannot afford to let it disappear like the Lop Nur."