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The River Torrens is the most significant river of the Adelaide Plains and was one of the reasons for the siting of the city of Adelaide, capital of South Australia. It flows from its source in the Adelaide Hills near Mount Pleasant, across the Adelaide Plains, past the city centre and empties into Gulf St Vincent between Henley Beach South and West Beach. The upper stretches of the river and the reservoirs in its watershed supply a significant part of the city's water supply. The river's long linear parks and a constructed lake in the lower stretch are iconic of the city. At its 1836 discovery an inland bend was chosen as the site of the Adelaide city centre and North Adelaide. The river is named after Colonel Robert Torrens, chairman of the colonial commissioners and a significant figure in the city's founding. The river is also known by its native Kaurna name ''Karra wirra-parri''. The river and its tributaries are highly variable in flow, and together drain an area of . They range from sometimes raging torrents, damaging bridges and flooding city areas, to trickles and completely dry in summer. Winter and spring flooding has prompted the construction of flood reduction works. A constructed sea outlet, landscaped linear parks and three holding reservoirs contain peak flow. The river's flora and fauna have been both deliberately and accidentally impacted since settlement. In the 19th century, native forests were cleared, gravel removed for construction and many foreign species introduced. With construction of the linear parks, many species native to the river have been replanted, and introduced species have been controlled as weeds. Since European settlement the river has been a frequently touted tourist attraction. During the early years of settlement, the river acted as both the city's primary water source and main sewer, leading to outbreaks of typhus and cholera.〔 New site: http://www.amlrnrm.sa.gov.au Active on 9 September 2009.〕 ==Physiography== The River Torrens runs largely westward from the Adelaide Hills, through the centre of Adelaide to the Gulf St Vincent. It originates close to the eastern fault scarp of the Mount Lofty Ranges, near Mount Pleasant, approximately above sea level. It runs predominantly along faulted north-south ground structures, which were formed over 250 million years ago during the Paleozoic era then further dislocated during the Cretaceous and earliest Tertiary. There is a 400 metre subsidence along the Para Fault which also affects the rivers flow. This subsidence was formed in the last two million years, after the Pliocene era.〔Smith & Twidale 1987, p.v〕 From its origin to Birdwood the river follows rolling, relatively level country before entering a hilly section that continues to Gumeracha. The river then follows sedimentary rock strata before entering a gorge after Cudlee Creek. It flows through the gorge to Athelstone, passing over the Eden Fault Zone of the Adelaide Hills face and associated escarpment. After the scarp it flows over sedimentary rocks of varying resistance to erosion, which has led to interspersed narrows and broad basins.〔 From the base of the Adelaide Hills to Adelaide's central business district it runs in a shallow valley with a terraced floor, then down the slope of its own alluvial fan. The structure of this fan shows that the river formerly entered Gulf St Vincent via the Port River. Over time the Torrens deposited sediment, choking its own outflow; becoming locked behind coastal sand dunes and forming the swampy areas of the Cowandilla Plains and the reedbeds.〔 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「River Torrens」の詳細全文を読む スポンサード リンク
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