The length of a river can be very hard to calculate. There are many factors, such as the source, the identification or the definition of the mouth, and the scale of measurement of the river length between source and mouth, that determine the precise meaning of “river length”. As a result, the length measurements of many rivers are only approximations. In particular, there has long been disagreement as to whether the Nile or the Amazon is the world’s longest river. The Nile has traditionally been considered longer, but in recent years some Brazilian and Peruvian studies have suggested that the Amazon is longer by measuring the river plus the adjacent Pará estuary and the longest connecting tidal canal. For the purpose of determining maximum length a river’s “true source” is considered to be the source of whichever tributary is farthest from the mouth. This tributary may or may not have the same name as the main stem river. For example, the source of the Mississippi River is normally said to be Lake Itasca in the U.S. state of Minnesota, but the most distant source in the Mississippi system is that of the Jefferson River in the state of Montana, a tributary of the Missouri River which in turn is a tributary of the Mississippi. When the Mississippi is measured from mouth to this farthest source, it is called theMississippi-Missouri-Jefferson
10. Amur – Argun
The Amur is the world’s tenth longest river, forming the border between the Russian Far East (Outer Manchuria) and Northeastern China (Inner Manchuria). It rises in the hills of western Manchuria at the confluence of its two major affluents, the Shilka River and the Ergune River, at an elevation of 303 metres (994 ft). It flows east forming the border between China and Russia, and slowly makes a great arc to the southeast for about 400 kilometers (250 mi), receiving many tributaries and passing many small towns. At Huma, it is joined by a major tributary, the Huma River. Afterwards it continues to flow south until between the cities of Blagoveschensk (Russia) and Heihe (China), it widens significantly as it is joined by the Zeya River, one of its most important tributaries.
09. Congo – Chambeshi
The Congo River is a river in Africa, and is the deepest river in the world, with measured depths in excess of 220 m(720 ft). It is the third largest river in the world by volume of water discharged. Additionally, its overall length of 4,700 km(2,920 mi) makes it the ninth longest river. The sources of the Congo are in the highlands and mountains of the East African Rift, as well as Lake Tanganyika and Lake Mweru, which feed the Lualaba River, which then becomes the Congo below Boyoma Falls. The Chambeshi River in Zambia is generally taken as the source of the Congo in line with the accepted practice worldwide of using the longest tributary, as with the Nile River.
08. Paraná – Río de la Plata
The Paraná River is a river in south Central South America, running through Brazil, Paraguay and Argentina for some4,880 kilometers (3,030 mi). It is second in length only to the Amazon River among South American rivers. The name Paraná is an abbreviation of the phrase “para rehe onáva”, which comes from the Tupi language and means “like the sea” (that is, “as big as the sea”). It merges first with the Paraguay River and then farther downstream with the Uruguay River to form the Río de la Plata and empties into the Atlantic Ocean.
07. Ob – Irtysh
The Ob River is a major river in western Siberia, Russia and is the world’s seventh longest river. It is the westernmost of the three great Siberian rivers that flow into the Arctic Ocean (the other two being the Yenisei River and the Lena River). The Gulf of Ob is the world’s longest estuary. Ob-Irtysh system, the third-longest river system of Asia (after China’s Yangtze and Yellow rivers), is 5,410 kilometers (3,360 mi) long, and the area of its basin 2,990,000 square kilometers (1,150,000 sq mi).
06. Yellow River
The Yellow River is the second-longest river in China after the Yangtze and the sixth-longest in the world at the estimated length of 5,464 kilometers (3,395 mi). Originating in the Bayan Har Mountains in western China, it flows through nine provinces of China and empties into the Bohai Sea. The Yellow River basin has an east-west extent of 1900 km (1,180 mi) and a north-south extent of 1100 km (684 mi). Its total basin area is 742,443 km² (290,520 mi²).
05. Yenisei – Angara – Selenge
Yenisei is the fifth longest river in the world with length 5,539 km. Yenisei is the largest river system flowing to the Arctic Ocean. It is the central of the three great Siberian rivers that flow into the Arctic Ocean (the other two being the Ob River and the Lena River). Rising in Mongolia, it follows a northerly course to the Yenisei Gulf in the Kara Sea, draining a large part of central Siberia, the longest stream following the Yenisei-Angara-Selenga-Ider river system.
04. Mississippi – Missouri – Jefferson
The Mississippi River is the chief river of the largest river system in North America. Flowing entirely in the United States (though its drainage basin reaches into Canada), it rises in northern Minnesota and meanders slowly southwards for 2,530 miles (4,070 km) to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi’s watershed drains all or parts of 31 U.S. states between the Rocky and Appalachian Mountains and even reaches into southern Canada. The Mississippi ranks as the fourth longest and tenth largest river in the world.
03. Yangtze
The Yangtze is the longest river in Asia, and the third longest in the world. It flows for 6,418 kilometers (3,988 mi) from the glaciers on the Tibetan Plateau in Qinghai eastward across southwest, central and eastern China before emptying into the East China Sea at Shanghai. It is also one of the biggest rivers by discharge volume in the world. The Yangtze drains one-fifth of the land area of the People’s Republic of China (PRC) and its river basin is home to one-third of the PRC’s population. For thousands of years, man has used the river for water, irrigation, sanitation, transportation, industry, boundary-marking and war. The Three Gorges Dam on the Yangtze River is the largest hydro-electric power station in the world.
02. Amazon – Ucayali – Apurímac
The Amazon River in South America is the second longest river in the world and by far the largest by water-flow with an average discharge greater than the next seven largest rivers combined (not including Madeira and Rio Negro, which are tributaries of the Amazon). The Amazon, which has the largest drainage basin in the world, about 7,050,000 square kilometers (2,720,000 sq mi), accounts for approximately one-fifth of the world’s total river flow. In its upper stretches, above the confluence of the Negro River, the Amazon is called Solimões in Brazil; however, in Peru, Colombia and Ecuador, as well as the rest of the Spanish-speaking world, the river is generally called the Amazon downstream from the confluence of the Marañón and Ucayali rivers in Peru. The Ucayali-Apurímac river system is considered the main source of the Amazon.
01. Nile – Kagera
The Nile is a major north-flowing river in northeastern Africa, generally regarded as the longest river in the world. It is 6,650 km (4,130 miles) long. It runs through the ten countries of Sudan, South Sudan, Burundi, Rwanda, Democratic Republic of the Congo, Tanzania, Kenya, Ethiopia, Uganda and Egypt. The Nile has two major tributaries, the White Nile and Blue Nile. The White Nile is longer and rises in the Great Lakes region of central Africa, with the most distant source still undetermined but located in either Rwanda or Burundi. It flows north through Tanzania, Lake Victoria, Uganda and South Sudan. The Blue Nile is the source of most of the water and fertile soil. The two rivers meet near the Sudanese capital of Khartoum.
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