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Osmore River (also Moquegua, Ilo, or Tumilaca) system flows northeast to southwest in the Moquegua Region of southern coastal Peru. The river has its origin in the snow peaks of the Chuqi Ananta and Arundane mountains, at an elevation of (above sea level). It changes names as it descends from the Andes: From its origin it is called the Moquegua, then Osmore in the middle valley as Rio Coscori and Rio Tumilaca including where the river disappears into subterranean channels, and further down in the lower reaches as Rio Ilo. An initial reconnaissance of the archaeological treasures of the valley carried out in the 1980s revealed more than 500 archeological sites dated from 10,000 years of human occupation. The Asana archaeological site, occupied over a period of 8,000 years, is located by the Asana River, a tributary of the Osmore. There are also Wari culture sites, and the Tiwanaku culture sites in the area; this is where these two cultures came in contact. ==Geography== The river basin is situated within Moquegua Region's Mariscal Nieto and Ilo provinces. It is geographically located between parallels 16 º 52 'and 17 º 43' south latitude and between the meridians 70 º 26 'and 71 ° 20' west longitude. The hydrographic system is part of the Pacific slope.〔 The river flows along a geological fault known as Cholo fault, and flows over a length of draining an area of (of which are in a wet basin, located above 〔). It debouches in to the Pacific after dropping over a height of over in its short stretch of from the source and thus having a river gradient of 3.6% (close to a highway gradient). It has several tributaries which have their origin in the western cordillera. The river basin is bounded on the north by the Tambo River basin, which is a sub-basin of the Vizcachas River; on the east and south, with the Locumba River basin; and on the west by the Pacific Ocean and the region between Moquegua and Tambo, formed by a series of short and medium streams.〔 From north to south the tributaries are: the Huraicane River (also called Otora) with a drainage area of over a flow length of ; the Torata River (Quilancha River) draining in a river length of ; and the Moquegua (Tumilaca), the largest tributary with basin area of , which has two tributaries, the Coscori (formed by the Asana River and the Chareque) and the Capallune, flowing over a length of only. The upper Osmore drainage is known as the Otora Valley.〔 The middle section of the river came into prominence as Moquegua valley (formed by the lower tributaries) during the colonial rule and the town of the same name Moquegua was established. The lower end of the mid valley is where the river disappears from an elevation of about without any trace of either of the river or any habitation traces of pre-Hispanic or Hispanic colonial rule, and reappears short of the coast. Here it becomes a wide valley and flows through the town of Ila. In its last stretch, the river is joined by another stream which brings in the desert wash of the Quebrada Seca de Guaneros, a stream which drains over a stream length of . Many springs in the lower valley (broad valley with flood plains developed for agriculture) were tapped for irrigation development and the river in the lower section in the coastal valley is known by the ancient name of Rio Ilo (Ilo River) with coast line occupied by villages of fishermen. The upper section of the Osmore contains several valleys. The midsection contains farmland, the city of Moquegua, the historical Tiwanaku town of Omo, and the Yaral site. It is here that the river disappears into underground channels, leaving behind a gorge.〔 The floodplains initial are narrow, averaging in width, while the latter average in width when arriving at the sea. The presence of the Tiwanaku state's existence in the Moquegua Region was determined in 1981, with 17 sites located in the Osmore drainage area.〔 The small settlement of Pacocha was built at the mouth of the river. In the late 19th century, high tides of the Pacific Ocean flooded the town, and the residents relocated to Ilo, on higher ground. 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「Osmore River」の詳細全文を読む スポンサード リンク
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