China’s biggest freshwater lake can shrink to a puddle
Poyang Lake in Jiangxi’s Jiujiang Prefecture is China’s largest freshwater lake, fed by the Gan, Xin, and Xiu rivers before draining north into the Yangtze. A normal year averages about 3,500 square kilometres—yet early 2012 drought, sand mining, and Three Gorges storage shrank it to roughly 200.
As many as half a million migratory birds use the basin, and in winter up to ninety percent of the critically endangered Siberian crane population may roost there. During the Tang dynasty the lake is thought to have spread across about 6,000 square kilometres.
It is not the same body as the ancient Pengli Marsh. Before the Han dynasty the Yangtze took a more northerly line, and Pengli formed the lower Gan; the site of today’s lake was farmland along that river. Around AD 400 the Yangtze shifted south again, the Gan backed up, and the new lake swallowed Poyang and Haihun counties. Refugees moved to Wucheng, which grew into one of Jiangxi’s great old townships and inspired a proverb about Haihun drowning so Wucheng could rise.
Fishing bans began in 2002, and in January 2020 China imposed a ten-year moratorium at 332 Yangtze sites, Poyang among them. The finless porpoise, nicknamed jiangzhu or river pig, is the reason for much alarm: by 2007 roughly 1,400 remained, about 500 of them in Poyang and Dongting, fewer than half the 1997 figure and falling by some 7.3 percent a year, raising fears it could vanish like the baiji dolphin.
Sand dredging brings the lakeside region valuable income but is blamed as the leading killer of local wildlife. Cloudier water shortens the porpoises’ sight so they lean on sonar, while large ships passing at about two a minute drown out the sounds of prey and block crossings between banks. A planned Poyang dam is expected to hit the survivors hard, and upstream Three Gorges operations can leave the lake shrunken or dry in some seasons.
Source: Poyang Lake
