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The Manas Lake () is a salt lake in China's Xinjiang Uighur Autonomous Region. It is located in the western part of the Dzungarian Basin, within the Gurbantünggüt Desert. Administratively, the lake is in Hoboksar Mongol Autonomous County; the closest urban settlement is Urho District of Karamay City, some 40 km to the northwest of the lake. The Manas Lake used to be known as the Yihehake Lake (伊赫哈克湖, Yīhèhākè hú) in the past.〔 Notionally, Lake Manas is considered the end point of the Manas River, flowing from the Tian Shan mountains. In practice, however, the river bed is usually dry where it reaches the lake (), and little river water reaches the lake. The Manas Lake area is characterized by arid climate with hot summers; the average annual precipitation of merely 63.7 mm, as compared to the average annual evaporation of 3,110.5 mm; which means that without an inflow of water from outside, the lake's water level can drop very quickly. Over the second half of the 20th century and the early years of the 21st century, it went through the cycle of shrinking, drying up, recovering, or existing as an intermittent lake. ==Geological history== According to the research by Chinese geologists, area occupied by today's Manas Lake was in the past part of a much large lake, the Old Manas Lake, which exited in the northwestern part of the Dzungarian Basin. It is believed that the Old Manas Lake was formed in the Early Pleistocene and existed throughout the Early Quaternary. Due to tectonic movements in the Middle Quaternary, many important rivers that used to flow to the Old Manas Lake started flowing elsewhere. The Irtysh now flows toward the Arctic Ocean, and the Ulungur River ends in the Ulungur River; the Maqiao River, south of Lake Manas, does not reach it either. Study of the old alluvial fans and lacustrine terraces seems to indicate that the Old Manas Lake's level was at about 280 meters above the sea level.〔 As the Old Manas Lake lost most of its water sources, its water level dropped in the Late Quaternary, and it split into several lakes including the Manas Lake, the Ailik Lake (which presently is the end point of the Baiyang River), and the Alan Nur.〔 According to the early 20th century maps, a large lake in the region of today's Manas Lake was the Alan Nur (, or (,〔 (English abstract on p. 160)〕 located to the west of today's Manas Lake (); that was the lake into which the Manas River flowed.〔 Earlier (in 18th-19th centuries) the Alan Nur would receive, besides the Manas, also the waters of the Hutubi River (呼图壁河) and Santun River (三屯河). These two rivers flow from the Tian Shan into the Dzungarian Basin in Hutubi and Changji Counties; nowadays, they disappear in the desert a long distance away from the Manas Lake, but in the period under consideration they would merge and reach the Alan Nur.〔 Even though the Manas River flowed into the Alan Nur, the lake now known as the Manas Lake existed as well; it was fed primarily by streams coming from the northern rim of the Zhungarian Basin〔 (i.e., from the Saur Mountains); this is indicated by old alluvial fans still existing at the pertinent locations.〔 It is believed that due to tectonic movements in the early 20th century, the earth surface around Alan Nur was rising and around Manas Lake, lowering; besides, the lower course of the Manas River was silting up with the sediment brought by the river. As a result, in 1915 the main stream of the Manas River changed its course, now flowing to the Manas Lake; however, a small branch feeding into the Alan Nur remained.〔 (One can see the bifurcation point of the now-dry river beds at , with the main channel going to the north-east and entering the Manas Lake around , while the old channel enters the former Alan Nur at .) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Manas Lake」の詳細全文を読む スポンサード リンク
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