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Portal:Rivers

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The Rivers Portal

Introduction

A boat floats on the Mekong, in Laos

A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it runs out of water, or only flow during certain seasons. Rivers are regulated by the water cycle, the processes by which water moves around the Earth. Water first enters rivers through precipitation, whether from rainfall, the runoff of water down a slope, the melting of glaciers or snow, or seepage from aquifers beneath the surface of the Earth.

Rivers flow in channeled watercourses and merge in confluences to form drainage basins, or catchments, areas where surface water eventually flows to a common outlet. Rivers have a great effect on the landscape around them. They may regularly overflow their banks and flood the surrounding area, spreading nutrients to the surrounding area. Sediment or alluvium carried by rivers shapes the landscape around it, forming deltas and islands where the flow slows down. Rivers rarely run in a straight line, instead, they bend or meander; the locations of a river's banks can change frequently. Rivers get their alluvium from erosion, which carves rock into canyons and valleys.

Rivers have sustained human and animal life for millennia, including the first human civilizations. The organisms that live around or in a river such as fish, aquatic plants, fungi, molluscs, and insects have different roles, including primary production, processing organic matter, predation, parasitism, and decomposition. Rivers have produced abundant resources for humans, including food, transportation, drinking water, and recreation. Humans have throughout history engineered rivers to prevent flooding, irrigate crops, perform work with water wheels, and produce hydroelectricity from dams. Since ancient times, people have associated rivers with life and fertility and have attached strong religious, political, social, and mythological elements to them. To this day, more than 90% of the human population lives within 10 miles of a river. (Full article...)

The Mississippi drainage basin includes the two longest main-stem rivers in the U.S. (the Missouri and the Mississippi) as well as 18 more of the rivers on this list.
The Mississippi drainage basin includes the Missouri and the Mississippi rivers, the two longest main-stem rivers in the United States, as well as 18 more of the rivers on this list. The Mississippi main stem is highlighted in dark blue.

The longest rivers of the United States include 38 that have main stems of at least 500 miles (800 km) long. The main stem is "the primary downstream segment of a river, as contrasted to its tributaries". The United States Geological Survey (USGS) defines a main-stem segment by listing coordinates for its two end points, called the source and the mouth. Some well-known rivers like the Atchafalaya, Willamette, and Susquehanna are not included in this list because their main stems are shorter than 500 miles.

Seven rivers in this list cross or form international boundaries. Three—the Milk River, the Red River of the North, and the Saint Lawrence River—begin in the United States and flow into Canada; two do the opposite (Yukon and Columbia). Also a segment of the Saint Lawrence River forms the international border between part of the province of Ontario, Canada, and the U.S. state of New York. Of these seven rivers, only the Milk River crosses the international border twice, leaving and then re-entering the United States. Two rivers, the Colorado and the Rio Grande, begin in the United States and flow into or form a border with Mexico. In addition, the drainage basins of the Mississippi and Missouri rivers extend into Canada, and the basin of the Gila River extends into Mexico. (Full article...)

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Rivers know this: There is no hurry, we shall get there some day.

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Photograph: NASA

The San Juan River and the entrenched meanders of Goosenecks State Park in Utah.

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The following are images from various river-related articles on Wikipedia.

Did you know?

  • ... that the River Poddle, the main water source of the city of Dublin for over 500 years, was later so polluted by industry that it allegedly killed cattle and horses drinking from it?
  • ... that six different dams were proposed for the lower Sanpoil River?
  • ... that radio station WWBC in Cocoa, Florida, was forced to remove its transmitter tower from the Indian River when the site was sold to condominium developers?

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Tagus River
Tagus River
Photograph: David Iliff
The Tagus River, seen here passing through the World Heritage listed city of Toledo, Spain. It is the longest river on the Iberian Peninsula at 1,038 kilometres (645 mi). It begins its journey in the Albarracín mountains in Spain, and follows a very constricted course for much of its length before reaching the Atlantic Ocean in Portugal.

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