China’s largest lake is salty, alkaline, and sky-blue named
Qinghai Lake—China’s biggest lake and the namesake of Qinghai Province—is an alkaline endorheic salt lake on the Tibetan Plateau. In 2008 it covered about 4,317 square kilometres, averaging 21 metres deep and reaching 25.5. It shrank through much of the twentieth century but has grown since 2004.
Classical Chinese qīng covered both blue and green, so translations swing between Blue Sea and Green Sea; the Mongolian Koko Nor and Tibetan Tso ngönpo likewise describe blue-green water. The basin lies about 100 kilometres west of Xining at 3,205 metres, between the Haibei and Hainan Tibetan prefectures.
Twenty-three rivers flow in, most only seasonally, and five permanent streams deliver about eighty percent of the water. With little inflow and strong evaporation, the lake holds roughly 1.4 percent salt by weight and a pH near 9.3. It was cut off from the Yellow River about 150,000 years ago, and a rise of some fifty metres would reopen the link through a pass to the east. Off the tip of a western peninsula, Cormorant Island and Egg Island together make up the Bird Islands.
Levels have swung widely. About 18,000 years ago, just after the Last Glacial Maximum, the surface sat roughly thirty metres lower than now. It climbed to within ten metres of today’s height between 15,600 and 10,700 years ago, dipped, rose again from about 9,200 years ago and peaked a few metres above the present level around 5,900 years ago, before a cooler, drier spell pulled it down until about 1,400 years ago.
Winters here are bitterly cold but very dry, and the lake often stays frozen for three months at a stretch; summers bring mild afternoons, chilly mornings and frequent showers. Han Chinese settled the Xining valley to the east during the Han dynasty, and in the seventeenth century Oirat and Khalkha Mongols moved in and became known as the Qinghai Mongols. After their 1724 revolt under Lobzang Danjin failed, the Yongzheng Emperor ended the region’s autonomy and imposed direct rule.
Source: Qinghai Lake
