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Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, in both cases, after only Lake Baikal in Siberia;〔(【引用サイトリンク】title=~ZAMBIA~ )〕 it is also the world's longest freshwater lake. The lake is divided among four countries – Tanzania, Democratic Republic of the Congo, Burundi, and Zambia, with Tanzania (46%) and DRC (40%) possessing the majority of the lake. The water flows into the Congo River system and ultimately into the Atlantic Ocean. The name apparently refers to "Tanganika, 'the great lake spreading out like a plain', or 'plain-like lake'."〔Stanley, H.M., 1899, Through the Dark Continent, London: G. Newnes, Vol. One ISBN 0486256677, Vol. Two ISBN 0486256685〕 ==Geography== Lake Tanganyika is situated within the Albertine Rift, the western branch of the East African Rift, and is confined by the mountainous walls of the valley. It is the largest rift lake in Africa and the second largest lake by volume in the world. It is the deepest lake in Africa and holds the greatest volume of fresh water, accounting for 18% of the world's available fresh water. It extends for in a general north-south direction and averages in width. The lake covers , with a shoreline of , a mean depth of and a maximum depth of (in the northern basin). It holds an estimated .〔(【引用サイトリンク】title=Datbase Summary: Lake Tanganyika )〕 It has an average surface temperature of and a pH averaging 8.4. The enormous depth and tropical location of the lake can prevent 'turnover' of water masses, which means that much of the lower depths of the lake are so-called 'fossil water' and are anoxic (lacking oxygen). The catchment area of the lake is . Two main rivers flow into the lake, as well as numerous smaller rivers and streams (whose lengths are limited by the steep mountains around the lake). There is one major outflow, the Lukuga River, which empties into the Congo River drainage. The major river flowing into the lake is the Ruzizi River, formed about 10,000 years ago, which enters the north of the lake from Lake Kivu. The Malagarasi River, which is Tanzania's second largest river, enters the east side of Lake Tanganyika. The Malagarasi is older than Lake Tanganyika and, before the lake was formed, directly drained into the Congo River. The lake has a complex history of changing flow patterns, due to its high altitude, great depth, slow rate of refill and mountainous location in a turbulently volcanic area that has undergone climate changes. Apparently it has rarely in the past had an outflow to the sea. It has been described as 'practically endorheic' for this reason. The lake's connection to the sea is dependent on a high water level allowing water to overflow out of the lake through the Lukunga into the Congo. Due to the lake's tropical location, it suffers a high rate of evaporation. Thus it depends on a high inflow through the Ruzizi out of Lake Kivu to keep the lake high enough to overflow. This outflow is apparently not more than 12,000 years old, and resulted from lava flows blocking and diverting the Kivu basin's previous outflow into Lake Edward and then the Nile system, and diverting it to Lake Tanganyika. Signs of ancient shorelines indicate that at times Tanganyika may have been up to 300 m lower than its present surface level, with no outlet to the sea. Even its current outlet is intermittent and may not have been operating when first visited by Western explorers in 1858. The lake may also have at times had different inflows and outflows: inward flows from a higher Lake Rukwa, access to Lake Malawi and an exit route to the Nile have all been proposed to have existed at some point in the lake's history. 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「Lake Tanganyika」の詳細全文を読む スポンサード リンク
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