Portal:Rivers

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The Rivers Portal

Introduction

Elwha River in the Olympic Peninsula

A river is a natural flowing watercourse, usually a freshwater stream, flowing on the Earth's land surface or inside caves towards another waterbody at a lower elevation, such as an ocean, sea, bay, lake, wetland, or another river. In some cases, a river flows into the ground or becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to by names such as creek, brook, and rivulet. There are no official definitions for these various generic terms for a watercourse as applied to geographic features, although in some countries or communities, a stream is customarily referred to by one of these names as determined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and Northeast England, and "beck" in Northern England. Sometimes a river is defined as being larger than a creek, but not always; the language is vague.

Rivers are an important part of the water cycle. Water from a drainage basin generally collects into a river through surface runoff from precipitation, meltwater released from natural ice and snowpacks, and other underground sources such as groundwater recharge and springs. Rivers are often considered major features within a landscape; however, they actually only cover around 0.1% of the land on Earth. Rivers are also an important natural terraformer, as the erosive action of running water carves out rills, gullies, and valleys in the surface as well as transferring silt and dissolved minerals downstream, forming river deltas and islands where the flow slows down. As a waterbody, rivers also serve crucial ecological functions by providing and feeding freshwater habitats for aquatic and semiaquatic fauna and flora, especially for migratory fish species, as well as enabling terrestrial ecosystems to thrive in the riparian zones.

Rivers are significant to humankind since many human settlements and civilizations are built around sizeable rivers and streams. Most of the major cities of the world are situated on the banks of rivers, as they are (or were) depended upon as a vital source of drinking water, for food supply via fishing and agricultural irrigation, for shipping, as natural borders and/or defensive terrains, as a source of hydropower to drive machinery or generate electricity, for bathing, and as a means of disposing of waste. In the pre-industrial era, larger rivers were a major obstacle to the movement of people, goods, and armies across regions. Towns often developed at the few locations suitable for fording, building bridges, or supporting ports; many major cities, such as London, are located at the narrowest and most reliable sites at which a river could be crossed via bridges or ferries. (Full article...)

Waterfall in Macleay Park

Balch Creek is a 3.5-mile (5.6 km) tributary of the Willamette River in the U.S. state of Oregon. Beginning at the crest of the Tualatin Mountains (West Hills), the creek flows generally east down a canyon along Northwest Cornell Road in unincorporated Multnomah County and through the Macleay Park section of Forest Park, a large municipal park in Portland. At the lower end of the park, the stream enters a pipe and remains underground until reaching the river. Danford Balch, after whom the creek is named, settled a land claim along the creek in the mid-19th century. After murdering his son-in-law, he became the first person legally hanged in Oregon.

Basalt, mostly covered by silt in the uplands and sediment in the lowlands, underlies the Balch Creek watershed. The upper part of the watershed includes private residential land, the Audubon Society of Portland nature sanctuary, and part of Forest Park. Mixed conifer forest of Coast Douglas-fir, western redcedar, and western hemlock with a well-developed understory of shrubs and flowering plants is the natural vegetation. Sixty-two species of mammals and more than 112 species of birds use Forest Park. A small population of coastal cutthroat trout resides in the stream, which in 2005 was the only major water body in Portland that met state standards for bacteria, temperature, and dissolved oxygen. (Full article...)
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Cherish these rivers. Witness for them. Enjoy their un-improvable purpose as you sense it, and let those rivers that you never visit comfort you with the assurance that they are there, doing wonderfully what they have always done.
David Brower, Foreword to Oregon Rivers, 1997

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Photograph: Ansel Adams

The Tetons and the Snake River (1942)

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Kettle Creek

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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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