Portal:Rivers

The Rivers Portal

Introduction

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, areas where surface water eventually flows to a common outlet. Drainage divides keep rivers separated from other courses of water and causes upstream water within the confines of the divide to fall into the downhill stream. 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, and insects have different roles, including processing organic matter and predation. Rivers have produced abundant resources for humans, including food, transportation, drinking water, and recreation. Humans have engineered rivers to prevent flooding, irrigate crops, perform work with water wheels, and produce hydroelectricity from dams. People associate rivers with life and fertility and have strong religious, political, social, and mythological attachments to them. (Full article...)

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Upper Tryon Creek in Marshall Park

Tryon Creek is a 4.85-mile (7.81 km) tributary of the Willamette River in the U.S. state of Oregon. Part of the drainage basin of the Columbia River, its watershed covers about 6.5 square miles (16.8 km²) in Multnomah and Clackamas counties. The stream flows southeast from the Tualatin Mountains (West Hills) through the Multnomah Village neighborhood of Portland and the Tryon Creek State Natural Area to the Willamette in the city of Lake Oswego. Parks and open spaces cover about 21 percent of the watershed, while single-family homes dominate most of the remainder. The largest of the parks is the state natural area, which straddles the border between the two cities and counties.

The bedrock under the watershed includes part of the last exotic terrane, a chain of seamounts, acquired by the North American Plate as it moved west during the Eocene. Known as the Waverly Hills Formation, it lies buried under ash and lava from later volcanic eruptions, sediments from flooding and erosion, and layers of wind-blown silt. Two dormant volcanoes from the Boring Lava Field are in the Tryon Creek watershed. (Full article...)

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

— A. A. Milne, Winnie-the-Pooh

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Photograph: Ansel Adams

The Tetons and the Snake River (1942)

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

Image 1Common water hyacinth in flower (from River ecosystem)
Image 2Pondweed is an autochthonous energy source. (from River ecosystem)
Image 3The Effra is one of the subterranean rivers of London. It empties into the Thames by Vauxhall Bridge, from which this photograph was taken. (from Subterranean river)
Image 4A whitewater canoe with yellow air bags. (from Whitewater)
Image 5A subterranean river in the Cross Cave system of Slovenia. (Scale shown by people in photograph.) (from Subterranean river)
Image 6Rafting is a watersport where buoyancy aids, helmets and wetsuits are mandatory and often imposed by law, due to the constant risk of falling off the boat and into the rapids (from Whitewater)
Image 7This stream operating together with its environment can be thought of as forming a river ecosystem. (from River ecosystem)
Image 8A pensive Cooplacurripa River, NSW (from River ecosystem)
Image 9New Zealand longfin eels can weigh over 50 kilograms. (from River ecosystem)
Image 10Anthropogenic influences on river systems. Examples are mainly from settings with a modest technological influence, especially in the period of about 10,000 to 4000 cal yr BP. (from River ecosystem)
Image 11Devil's Throat Cave subterranean river from above (from Subterranean river)
Image 12Periphyton (from River ecosystem)
Image 13Leaf litter is an allochthonous energy source. (from River ecosystem)
Image 14In Dante's Inferno, Charon ferries souls across the subterranean river Acheron. (from Subterranean river)
Image 15The Puerto Princesa cave can be entered by boat. (from Subterranean river)
Image 16The cave of source of the Buna can be entered by boat and dived through a cave system serving as an effluence of the Zalomka. (from Subterranean river)
Image 17The brook trout is native to small streams, creeks, lakes, and spring ponds. (from River ecosystem)
Image 18Rapids in Mount Robson Provincial Park (from River ecosystem)
Image 19Example of a river food web. Fungi (aquatic hyphomycetes) and Bacteria can be seen in the red box at the bottom. Fungi and bacteria (and other decomposers, like worms) decompose and recycle nutrients back to the habitat, which is shown by the light blue arrows. Without fungi and bacteria, the rest of the food web would starve, because there would not be enough nutrients for the animals higher up in the food web. The dark orange arrows show how some animals consume others in the food web. For example, lobsters may be eaten by humans. The dark blue arrows represent one complete food chain, beginning with the consumption of algae by the water flea, Daphnia, which is consumed by a small fish, which is consumed by a larger fish, which is at the end consumed by the great blue heron. (from River ecosystem)
Image 20Flowing rivers can act as dispersal vectors for plant matter and invertebrates. (from River ecosystem)
Image 21Different biofilm components in streams. Principal components are algae and bacteria. (from River ecosystem)
Image 22A weir on the River Calder, West Yorkshire (from River ecosystem)
Image 23Whitewater at Yosemite (from Whitewater)
Image 24Co-occurrence network of a bacterial community in a stream (from River ecosystem)
Image 25A forest stream in the winter near Erzhausen, Germany (from River ecosystem)
Image 26Map of the world showing elevation levels (from Upland and lowland)
Image 27Cascade in the Pyrénées (from River ecosystem)
Image 28Castle Geyser, Yellowstone National Park (from River ecosystem)

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Did you know?

... that the 2010 sockeye salmon run on the Adams River (pictured) in British Columbia, Canada, is expected to be the largest since 1913, with an estimated 9 million fish returning to the river to spawn?
... that three swimming holes on Big Wapwallopen Creek are the most dangerous ones in Luzerne County, Pennsylvania?
... that the name for the Texas stream Cibolo Creek comes from the Native American and Spanish word for Buffalo, who were hunted along its steep banks?

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