China's Largest Freshwater Lake Shrinks in Record Drought

Environment News Service 5 Jan 12;

NANCHANG, Jiangxi Province, China, January 5, 2012 (ENS) - The surface area of China's largest freshwater lake has shrunk to less 200 square kilometers (77 square miles) due to China's worst drought in 50 years, according to the Jiangxi Provincial Hydrographic Bureau.

Poyang Lake, situated in the southeastern province of Jiangxi, is fed by five rivers and empties into the Yangtze, China's longest river.

Statistics released by the hydrographic bureau to the state-run Xinhua News Agency show that average precipitation in Jiangxi in 2011 was 21 percent lower than the annual average in the past several years.

Currently, the water level of the middle and lower reaches of the Ganjiang River, one of the five rivers that flows into the lake, has reached a record low for this time of year of 12.35 meters (40.5 feet). This level is 0.47 meters (1.5 feet) lower than the previous record low for January, according to the hydrographic bureau.

Cities along the Ganjiang River are preparing for a possible water shortage, the bureau said on Wednesday

The shrinking of Poyang Lake has been going on for years. In June 2011, provincial officials announced that the lake was 87 percent smaller than it had been in previous years due to the drought that has plagued the middle and lower reaches of the Yangtze River for months.

In April 2011, workers at the lake's main water station, recorded the water level at just 9.48 meters (31 feet), which was 4.1 meters (13.4 feet) lower than at any point in its history, said a spokesman with the Poyang Hydrology Bureau at the time.

The lake provides habitat for half a million migratory birds, including the only surviving population of critically endangered Siberian white cranes.

The lake also is inhabited by some 140 kinds of fish and about 600 other animal species.

Sand dredging has become a mainstay of local economic development in the last few years, and is an important source of revenue in the region that borders Poyang Lake. But high-density dredging projects and heavy shipping traffic in the lake have resulted in the decline of for the local wildlife population, particularly the unique and endangered freshwater finless porpoise, N. a. asiaeorientalis, according to a 2007 report by Kejia Zhang of the "China Youth Daily."

The Yangtze River once was ideal habitat for these unique porpoises, but human economic activity has squeezed them into Poyang Lake and Dongting Lake, where they are only just surviving, Wang Ding, deputy director of the Institute of Hydrobiology, Chinese Academy of Sciences, told Zhang for her report.

"An optimistic estimate would put numbers at no more than 1,400 - less than half of the 1997 population. But although the porpoise population is currently dropping at a rate of 7.3 percent per year, it still has a hope of survival - if enough action is taken," said Wang.

Jiangxi Province plans to build a 2,800-meter (9,186 foot) high dam to protect Poyang Lake from the impact of the world's largest dam, the Three Gorges dam on the Yangtze River, provincial officials said in June.

The Three Gorges dam has had a great impact on Poyang Lake because it prevents Yangtze River water from entering the lake, Wang Xiaohong, director of the Mountain, River and Lake Development Committee of the province, told the Shanghai newspaper in June.

Water levels had been above 19.5 meters (64 feet) but dropped to only 16 meters (52.5 feet) after the main part of the Three Gorges dam was completed in 2006, the report said.

The Poyang dam plan was approved by the State Council, the country's Cabinet, in December 2009, but work has yet to begin as experts fear the dam might worsen the situation of the lake.

On May 18, 2011, the State Council issued a statement promising continued efforts to protect the environment, prevent geological disasters and minimize the Three Gorges Dam's impact on the middle and lower reaches of the Yangtze River.

Lake Poyang reached its greatest size during the Tang Dynasty, 618-907 A.D., when it covered 6,000 square kilometers.