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The Pastaza River ((スペイン語:Río Pastaza), formerly known as the Sumatara〔Enock, Charles Reginald (1914) ''Ecuador: its ancient and modern history, topography and natural resources, industries and social development'' Charles Scribner's sons, New York, (pages 177–178 ), 〕) is a large tributary to the Marañón River in the northwestern Amazon Basin of South America.〔Ziesler, R. and G.D. Ardizzone, G.D. (1979) ("Amazon System" ) ''Las Aguas Continentales de America Latina / The Inland Waters of Latin America'' (COPESCAL Technical Paper No. 1) Fisheries and Aquaculture Department, Food and Agriculture Organization of the United Nations (FAO), Rome, ISBN 92-5-000780-9, in English and Spanish〕 It has its headwaters in the Ecuadorian province of Cotapaxi, flowing off of the northwestern slopes of the volcano Cotopaxi and known as the Patate River. The Patate flows south and in Tungurahua Province it is joined by the Chambo River just upstream from the town of Baños de Agua Santa just north of the volcano Mount Tungurahua and becomes the Pastaza.〔Instituto Geografico Militar del Ecuador, Mapa Tungurahua 50,000:1〕〔Topographic map (Baños, Ecuador, Series J721, Sheet 3989 IV, 1:50,000 ) Instituto Geográfico Militar (IGM), Quito, Ecuador, September 2000, reprinted by the U.S. National Imagery and Mapping Agency〕 Seven kilometers east of Baños, it is dammed for the Agoyan hydroelectic project, which has created a silty lagoon by the village of La Cieniga.〔 The Agoyan dam was placed in that location specifically to leave the famous Falls of Agoyan, about 5 km further downstream, intact. After the waterfall the river enters a gorge where there is very fast whitewater with class-4 rapids; it is often used for whitewater rafting although it is not considered to be of the same quality as the Tena River and is therefore less popular for the sport.〔Guia Turistica del Tungurahua, Ministerio de Turismo Ecuador〕 From the junction with the Chambo, the Pastaza flows almost due east for about where it then turns south-east, as it is joined by the Topo River.〔Topographic map (Rio Negro, Ecuador, Series J721, Sheet 3990 II, 1:50,000 ) Instituto Geográfico Militar (IGM), Quito, Ecuador, June 1996, reprinted by the U.S. National Imagery and Mapping Agency〕 The Troncal Amazonas highway parallels the river from Baños to Puyo, passing through seven tunnels, and four major waterfalls that are touristic destinations for many Ecuadorians (Agoyan and Pailon del Diablo being the most popular.) Just past the town of Santa Inez, the Pastaza River crosses into the province of Pastaza, where it forms the boundary between that province and Morona-Santiago. At the town of Mera, shortly before reaching Puyo, the river exits the mountains and flows into a wide valley, becoming wider and shallower.〔Topographic map Mera, Ecuador, Series J721, Sheet 3989-I, 1:50,000, Instituto Geográfico Militar (IGM), Quito, Ecuador, 1989, a reduced image is available from IGM at (http://www.igm.gob.ec/site/files/cartabase/enie/imagenes/ENIEIV_D2_ALTA.jpg )〕 After Shell Mera the river becomes braided and meanders, leaving oxbows and sloughs along its route across the Amazonian floodplain. After cutting through Ecuador, the Pastaza passes into Peru at the village of Hito Zoilaluz on Isla Zoilaluz〔Topographic map (Checherta, Peru, Series J632, Sheet 1565, 1:100,000 ) Instituto Geografico Nacional (IGN), Lima, Peru, June 1995, reprinted by the U.S. National Imagery and Mapping Agency〕 and flows south into the Marañón River near San Ramón.〔Topographic map (San Isidro, Peru, Series J632, Sheet 1661, 1:100,000 ) Instituto Geografico Nacional (IGN), Lima, Peru, October 1993, reprinted by the U.S. National Imagery and Mapping Agency〕 ==Tributaries== The Pastaza has numerous tributaries, both above and below the hydroelectric dam. These contribute to its rapid flow and to its tendency to flood. On the highway side of the Pastaza, a tributary river occurs about every 3–4 km for a stretch of about 50 km; on the opposite bank, the number of tributaries is slightly lower. The major tributaries are the Chambo, Bobonaza, and Huasaga,〔 also important are the Ambato, the Pindo, and the Puyo. 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「Pastaza River」の詳細全文を読む スポンサード リンク
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