Thursday, August 30, 2012
Saving China's Largest Freshwater Lake
Poyang Lake is China's largest freshwater lake, covering 4,000 square kilometers. It is home to more than 300 species of birds and 120 species of fish. Zhang Haiyan / For China Daily
Fisherman Zhang Qiulin said he has been anxious following the dramatic decrease of water levels on Poyang Lake over the last two weeks, despite the fact that the area is still in its rainy season.
Zhang said he fears a repeat of last year, when a historic drought killed many fish in Poyang, located in central China's Jiangxi Province.
Data from the provincial hydrographic bureau showed that the lake's water level had plummeted to 17.71 meters as of Sunday morning, down from this year's highest level of 19.65 meters on Aug. 13.
"Poyang has been drying up over the past decade, particularly from 2003 to 2008. During that time, its annual runoff was 23.2 billion cubic meters, or 15 percent, less than the average of previous years," said Wang Hao, a water conservancy expert with the China Institute of Water Resources and Hydropower Research.
Wang said the situation is likely to worsen due to the growing threat of climate change, which has been blamed for the lake's decreasing water level alongside human activity.
The average precipitation in Jiangxi in 2011 was 21 percent lower than the annual average for the past several years, the bureau's statistics indicated.
Reduced rainfall, rampant sand dredging and tourism-related exploitation have reduced the lake's size from 4,000 square km to about 200 square km.
The Three Gorges Dam and other projects built in the upstream areas of the Yangtze River caused the lake's dry season to arrive earlier than before, Wang said.
"A water conservancy project is needed at the mouth of Poyang, where water from the lake flows into the Yangtze River. The project could maintain water levels during the dry season and won't disturb water flows during the flood season," Wang said.
The lake's water volume and quality have a significant impact on Yangtze, as the lake's water discharges account for 15.6 percent of the river's annual runoff.
Moreover, the lake is a key water supply source for about 1 million people and an important home for numerous migratory birds and aquatic species.
A decline in the lake's water quality and degeneration of its ecology have worried environmental experts as well. Marion Hammerl, president of the Global Nature Fund, said urgent action by the international community is needed to halt the contamination of freshwater lakes, including the Poyang.
The Jiangxi provincial government has made some efforts to limit the exploitation of the lake, including shutting down construction cites and encouraging the development of a "recycling economy," said Hu Zhenpeng, vice chairperson of the local legislature.
The government has also moved to treat water on the branches of the Yangtze and prevent pollutants from entering the lake, Hu said.
Hammerl said the way water resources are managed should be transformed and existing water facilities should be upgraded.
Obsolete irrigation equipment should be replaced so as to facilitate water-saving agriculture and achieve sustainable development for the lake, she said.