| Poyang Lake | |
|---|---|
| Primary inflows | 5 Rivers, primarily the Gan and Xiu |
| Catchment area | 162,225 km² |
| Basin countries | China |
| Max. length | 170 km |
| Max. width | 17 km |
| Surface area | 4400 km² (rainy season) 1000 km² (dry season) |
| Average depth | 8.4 m |
| Max. depth | 25.1 m |
| Water volume | 2.95 km³ |
| Residence time | 5,000 years |
| Surface elevation | 12 m |
Poyang Lake (Chinese: 鄱阳湖; pinyin: Póyáng Hú, Gan: Po-yong U), located in Jiangxi Province is the largest freshwater lake in China.[1]
It has a surface area of 3,585 km², a volume of 25 km³ and an average depth of eight meters. The lake provides a habitat for half a million migratory birds,[2] and is a favorite destination for birding. It is fed by the Gan, Xin, and Xiu rivers, which connect to the Yangtse through a channel.
During the winter, the lake becomes home to a large number of migrating Siberian cranes, up to 90% of which spend the winter there.
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Historically, although Poyang Lake has also been called Pengli Marsh (彭蠡澤) they are not the same. Before the Han Dynasty, the Yangtze followed a more northerly course through what is now Lake Longgan (龍感湖) whilst Pengli Marsh formed the lower reaches of the Gan River. The area that is now Poyang Lake was a plain along the Gan River. Around AD 400, the Yangtze River switched to a more southerly course, causing the Gan River to back up and form Lake Poyang. The backing up of the Gan River drowned Poyang County and Haihun County, forcing a mass migration to Wucheng Township in what is now Yongxiu County. Wucheng thus became one of the great ancient townships of Jiangxi Province. This migration gave birth to the phrase, "Drowning Haihun County gives rise to Wucheng Township"「淹了海昏縣，出了吳城鎮」.
Lake Poyang reached its greatest size during the Tang Dynasty, when its area reached 6000 km².
There has been a fishing ban in place since 2002.
In 2007 fears were expressed that China's finless porpoise, known locally as the jiangzhu ("river pig"), a native of the lake, might follow the baiji, the Yangtze river dolphin, into extinction.
Calls have been made for action to be taken to save the porpoise, of which there are about 1,400 left living, with between 700 and 900 in the Yangtze, with about another 500 in Poyang and Dongting Lakes.
2007 population levels are less than half the 1997 levels, and the population is dropping at a rate of 7.3 per cent per year.
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 at the same time, high-density dredging projects have been the principal cause of the death of the local wildlife population.
Dredging makes the waters of the lake muddier, and the porpoises cannot see as far as they once could, and have to rely on their highly-developed sonar systems to avoid obstacles and look for food. Large ships enter and leave the lake at the rate of two a minute and such a high density of shipping means the porpoises have difficulty hearing their food, and also cannot swim freely from one bank to the other.[3]
In 1363, the Battle of Lake Poyang took place there, and it is claimed to be the largest naval battle in history.
The lake has also been described as the "Chinese Bermuda Triangle". Many ships have disappeared while sailing in it. On 16 April 1945, a Japanese troop ship vanished without a trace with 200 sailors.
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