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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...)

Bore hitting the riverbank in 1994

The Severn bore is a tidal bore seen on the tidal reaches of the River Severn in south western England. It is formed when the rising tide moves into the funnel-shaped Bristol Channel and Severn Estuary and the surging water forces its way upstream in a series of waves, as far as Gloucester and beyond. The bore behaves differently in different stretches of the river; in the lower, wider parts it is more noticeable in the deep channels as a slight roller, while the water creeps across the sand and mudflats. In the narrower, upper reaches, the river occupies the whole area between its banks and the bore advances in a series of waves that move upstream. Near Gloucester, the advancing water overcomes two weirs, and sometimes one in Tewkesbury, before finally petering out.

Bores are present on about 130 days in the year, concentrated on the days immediately following the new and full moon. The size and precise timing of the bore depend on such things as the time of high tide, the barometric pressure, the wind speed and direction, the amount of water coming down the river and how well scoured the main drainage channels are. There are a number of viewpoints from which the bore can be seen, or viewers can walk along the river bank or floodbanks. Historically, the bore has been of importance to shipping visiting the docks at Gloucester, but this was alleviated by the construction of an alternative route, the Gloucester and Sharpness Canal, which opened in 1827. Nowadays the bore is of interest to surfers and canoeists who attempt to ride the waves. ( Full article...)
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I do not know much about gods; but I think that the river is a strong brown god—sullen, untamed and intractable.
T. S. Eliot, "Four Quartets," in The Dry Salvages

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Photograph: Christian Mehlführer

Horseshoe Bend is a horseshoe-shaped meander of the Colorado River in the Glen Canyon National Recreation Area, located 5 miles (8 km) downstream from the Glen Canyon Dam and Lake Powell, near the town of Page, Arizona. It is accessible via hiking trail or an access road.

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