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up the river Slang.
[Middle English rivere, from Anglo-Norman, from Vulgar Latin *rīpāria, from Latin, feminine of rīpārius, of a bank, from rīpa, bank.]
A natural, fresh-water surface stream that has considerable volume compared with its smaller tributaries. The tributaries are known as brooks, creeks, branches, or forks. Rivers are usually the main stems and larger tributaries of the drainage systems that convey surface runoff from the land. Rivers flow from headwater areas of small tributaries to their mouths, where they may discharge into the ocean, a major lake, or a desert basin.
Rivers flowing to the ocean drain about 68% of the Earth's land surface. Regions draining to the sea are termed exoreic, while those draining to interior closed basins are endoreic. Areic regions are those which lack surface streams because of low rainfall or lithoogic conditions.
Sixteen of the largest rivers account for nearly half of the total world river flow of water. The Amazon River alone carries nearly 20% of all the water annually discharged by the world's rivers. Rivers also carry large loads of sediment. The total sediment load for all the world's rivers averages about 22 × 109 tons (20 × 109 metric tons) brought to the sea each year. Sediment loads for individual rivers vary considerably. The Yellow River of northern China is the most prolific transporter of sediment. Draining an agricultural region of easily eroded loess, this river averages about 2 × 109 tons (1.8 × 109 metric tons) of sediment per year, one-tenth of the world average. See also Depositional systems and environments; Loess.
River discharge varies over a broad range, depending on many climatic and geologic factors. The low flows of the river influence water supply and navigation. The high flows are a concern as threats to life and property. However, floods are also beneficial. The ancient Egyptian civilization was dependent upon the Nile River floods to provide new soil and moisture for crops. Floods are but one attribute of rivers that affect human society. Means of counteracting the vagaries of river flow have concerned engineers for centuries. In modern times many of the world's rivers are managed to conserve the natural flow for release at times required by human activity, to confine flood flows to the channel and to planned areas of floodwater storage, and to maintain water quality at optimum levels. See also Floodplain; River engineering.
For more information on river, visit Britannica.com.
There are a few traces in 19th-century local traditions of a belief that certain rivers are malevolent, and will periodically take a human life. The best known is the Dart (Devon), about which there is a rhyme:
River of Dart, River of Dart,
Every year thou claimest a heart.
‘He didna know Darrant, he said it were nought but a brook. But Darrant got'im. They never saw his head, he threw his arms up, but Darrant wouldna let him go. Aye, it's a sad pity, seven children! But he shouldna ha' made so light o' Darrant. He knows now! Naught but a brook! He knows now!’ (Folk-Lore15 (1904), 99)
America's rivers played a vital role in the early exploration, settlement, and development of the country. Long before white settlers arrived on American shores and began following river channels into the country's interior, Native peoples had been canoeing the waterways of the continent. Some of the detailed maps the indigenous cartographers created still exist today.
River Pathways to Exploration
The exploration of America via river travel boasts a history that includes nearly every major waterway. Among the first European explorers was Captain John Smith, who in 1608 traveled the Potomac River, a body of water that traverses nearly 400 miles to form the fourth-largest watershed on the East Coast. Settlers established the colony of Maryland on the lower Potomac less than twenty-five years later, and colonization of the northern Virginia shore followed within a decade.
Commissioned by the Dutch East India Company, Captain Henry Hudson began his exploration of America's northeastern coast in 1609, eventually sailing into the mouth of a river near today's New York City. He hoped the river, now named the Hudson River, would offer a passage west to the Pacific. However, near the location of present-day Albany he found the river too shallow to continue and was forced to turn back.
The early seventeenth century also marked the first time the 1,200-mile-long Columbia River appeared on European maps—after Spanish maritime explorer Martin de Auguilar located it in the Pacific Northwest. That river would eventually become one of the many water highways used by the Lewis and Clark Expedition of 1804 to 1806. During that same expedition, Meriwether Lewis and William Clark depended heavily on the Missouri River, using it and its tributaries to transport them from St. Louis to the northern plains and on to Montana.
Without question, the Mississippi River has also played an important role in the European exploration of America. In 1673, Jacques Marquette and Louis Joliet traveled the Upper Mississippi River, descending the Wisconsin River and returning to Lake Michigan via present-day Illinois. Others soon followed, and the Mississippi quickly became a major artery of traffic.
Rivers As Sources for Early Industrial Transport and Power
The mid-1600s began to see rivers as major thoroughfares of transportation for moving both people and products, and there was scarcely a hamlet or a trading post that did not have water connection with the coast. Through the better part of three centuries, such rivers as the Saint Croix, Penobscot, Kennebec, Androscoggin, Saco, and Piscataqua bore millions of logs downstream from the vast forests of Maine until timber resources diminished.
The Merrimack River, until the coming of the railroads, carried a significant portion of New Hampshire's goods, principally timber and granite, to towns below, and especially to its nearest large market, Boston. Parts of New Hampshire and Vermont depended upon the Connecticut River. Northwestern Vermont and northern New York traded with Quebec and Montreal via the Richelieu and Saint Lawrence Rivers.
Rivers also became significant sources of power for sawmills and gristmills. Along the Piscataqua, which stretched from Maine to New Hampshire, a sawmill sprang up as early as 1631 that produced lumber, shingles, and barrel staves. A multitude of other sawmills that depended on river power followed.
Gristmills, or operations for grinding grain, also utilized rivers for generating power, as did rice and textile mills. In the early nineteenth century, the fast-running Willimantic River attracted many cotton manufacturers from Rhode Island and Massachusetts. They situated their water-powered cotton mills in Willimantic, Connecticut, and along the length of the Quinebaug and Shetucket Rivers. The city of Willimantic eventually became a major American center for silk thread and cloth production between the end of the Civil War and the outbreak of World War II.
Rivers As Sources of Transportation
During the eighteenth century, thousands of newcomers traveled up the western tributaries of the Susquehanna and Potomac Rivers, crossed the watershed, and followed the Youghiogheny, Monongahela, Conemaugh, and Allegheny Rivers downward to populate the Ohio Valley. The great Mississippi River system then became the settlers' highway, and their natural markets included the French communities of Saint Louis and New Orleans. Most were in favor of the War of 1812 because a conquest of Canada would add a new commercial outlet to the east through control of the Saint Lawrence River. George Washington and others warned that if better connections were not established with the Ohio Valley residents, their allegiance might follow their trade down the Mississippi to the Spaniards. The Mississippi River system played a significant role until the railroads began cutting across the natural trade routes.
Farther south, emigrants from Virginia and the Carolinas pushed up the James, Dan, Yadkin, and Catawba Rivers, through the mountains, to populate southwestern Virginia and northeastern Tennessee. The men of that region, in signifying their allegiance to the Revolution, spoke of themselves as "Men of the settlements beyond the Alleghenies, where the Watauga and the Holston flow to the Tennessee." Some of the earliest settlers of Nashville left a fort on the Holston River on 22 December 1779 and journeyed down the Holston and the Tennessee in flatboats. They worked up to the mouth of the Cumberland River, and traveled up the Cumberland to the site of Nashville, which they reached on 24 April 1780 after a journey of some 1,300 miles.
Down the lower Atlantic coast were many broad rivers, really estuaries, having tidewater far upstream from their mouths (Patuxent, Chester, Choptank, Nanticoke, Potomac, Rappahannock, York, James, Chowan, Roanoke, Pamlico, Cape Fear, Pee Dee, Santee, Cooper, Saint Johns, and others). These rivers were the chief highways for regular travel as well as for freight transport and saw much traffic in the early days. Great plantations clustered along them, with the mansions fronting the water.
Commercial River Transportation
With the coming of steam technology and before railroads replaced river transport, steamboats began to populate the rivers, particularly in the Midwest and South. Some steamboats traveled where channels were so narrow that they could not turn around except by backing into the mouth of a tributary stream; most could operate only in parts of the winter and spring, when the water was high. Rivers such as the Cumberland, where boats once ran 150 miles or more above Nashville, could pose difficulties for their navigators, and it was said that a town might hear a boat whistle across a bend in the early morning and not see the craft until late afternoon. Mark Twain, enamored with river travel and steamboats, once said a river is a "wonderful book [with] a new story to tell everyday."
In California, when the gold rush began in 1849, the Sacramento and San Joaquin Rivers were almost the only feasible way to travel from San Francisco to the mining regions. There were no steamboats, and many gold-seekers paid high fees for passage upstream in a skiff or yawl, with the understanding that they were to help with the rowing. Others traveled in slow-moving sailing vessels. A steamer built in New York for the Atlantic coast trade went safely around Cape Horn and began operating on the Sacramento River; and until another one followed it four months later, its rates were so high that it earned $20,000 or more on a round trip. After 1855, the Columbia River likewise became the main route to and from the Pacific coast from the mining regions of Idaho and northeastern Washington.
Rivers' Role in Warfare
Rivers have played an important part in the nation's warfare. The French and Indian War took place almost entirely along rivers or intervening lakes. The French came down the Allegheny to seize the forks of the Ohio and build Fort Duquesne. Washington marched by the Potomac, Wills Creek, and the Youghiogheny on his illfated expedition of 1754.
The Ohio River was perhaps the most noted pathway of Indian warfare in American history. For decades, the upper Missouri River saw frequent Indian attacks upon white trappers, traders, and settlers. Much of the fighting of the Revolutionary War in New York State was done on, or immediately near, the Hudson and Mohawk Rivers.
In the Civil War the Potomac, the Rapidan, Rappahannock, North Anna, Chickahominy, and James Rivers served as important strategic barriers in the East, along which armies aligned themselves or fought. The division of Union Gen. George B. McClellan's army by the Chickahominy in the Seven Days' Battles came near being its ruin. The Potomac below Washington, D.C., provided a waterway by which the North could move armies quickly to block the mouth of the James. In the Midwest and South the Mississippi and its tributaries were among the chief objects of strategy. The seizure of the Mississippi in 1863 split the Confederacy in two and presaged its downfall. The Tennessee River furnished the route used by Gen. Ulysses S. Grant's army to reach Chattanooga in the autumn of 1863, and the Battle of Wauhatchie was fought to keep it open. The Red River (southern) witnessed an important but unsuccessful Union expedition in 1864 aimed at Texas.
Decline of River Transportation
In 1862, Congress passed the first of several railroad acts that would eventually connect the continent, lessening the need for rivers as a major mode of transportation within the commercial, public, and military sectors. At the beginning of the twenty-first century, the U.S. Army Corps of Engineers Navigation Data Center reported declining commercial traffic on many of the nation's waterways.
Bibliography
Adams, Arthur G. The Hudson through the Years. Bronx, N.Y.: Fordham University Press, 1996.
Ambrose, Stephen E. Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West. New York: Simon and Schuster, 1996.
Dietrich, William. Northwest Passage: The Great Columbia River. Seattle: University of Washington Press, 1996.
Hahn, Thomas F. Cement Mills along the Potomac River. Morgan-town: West Virginia University Press, 1994.
Merrick, George By Ron. Old Times on the Upper Mississippi: Recollections of a Steamboat Pilot from 1854 to 1863. Minneapolis: University of Minnesota Press, 2001.
Powell, John Wesley, and Anthony Brandt. The Exploration of the Colorado River and Its Canyons. Washington, D.C.: National Geographic Society, 2002.
Reps, John W. Saint Louis Illustrated: Nineteenth-Century Engravings and Lithographs of a Mississippi River Metropolis. Columbia: University of Missouri Press, 1989.
Worster, Donald. A River Running West: The Life of John Wesley Powell. New York: Oxford University Press, 2001.
The lowest level to which a river can erode its bed is called base level. Sea level is the ultimate base level, but the floor of a lake or basin into which a river flows may become a local and temporary base level. Cliffs or escarpments and differences in the resistance of rocks create irregularities in the bed of a river and can thus cause rapids and waterfalls. A river tends to eliminate irregularities and to form a smooth gradient from its source to its base level. As it approaches base level, downward cutting is replaced by lateral cutting, and the river widens its bed and valley and develops a sinuous course that forms exaggerated loops and bends called meanders. A river may open up a new channel across the arc of a meander, thereby cutting off the arc and creating an oxbow lake.
Rivers modify topography by deposition as well as by erosion. River velocity determines quantity and size of rock fragments and sediment carried by the river. When the velocity is checked by changes of flow or of gradient, by meeting the water mass of lakes or oceans, or by the spreading of water when a stream overflows its banks, part of the load carried by the stream is deposited in the riverbed or beyond the channel. Landforms produced by deposition include the delta, the floodplain, the channel bar, and the alluvial fan and cone.
The discharge, or rate of outflow, of a river depends on the width of its channel and on its velocity. Velocity is governed by the volume of water, the slope of the bed, and the shape of the channel (which determines the amount of frictional resistance). River volume is affected by duration and rate of precipitation in the drainage basin of the river. A river system may be enlarged by piracy, or the process by which one river, cutting through the divide that separates its drainage basin from that of another river, diverts the waters of the other into its own channel.
Traditionally river systems have been classified according to their stage of development as young, mature, or old. The young river is marked by a steepsided valley, steep gradients, and irregularities in the bed; the mature river by a valley with a wide floor and flaring sides, by advanced headward erosion by tributaries, and by a more smoothly graded bed; and the old river by a course graded to base level and running through a peneplain, or broad flat area. The age classification of rivers is diminishing in popularity now that quantitative studies of river behavior are more common.
See also flood; water rights; waters, territorial.
Important River Systems
River valleys have been important centers of civilization; they afford travel routes, and their alluvial soils form good agricultural lands. Navigable rivers are important in commerce and have influenced the location of cities. Rivers with sufficient velocity and gradient can be used to produce hydroelectric power. Among the most important river systems of the world are the Nile, the Congo, the Niger, the Zambezi, and the Orange-Vaal in Africa; the Amazon, the Orinoco, and the Paraguay-Paraná in South America; the Mississippi-Missouri, the St. Lawrence, the Rio Grande, the Colorado, the Columbia, the Mackenzie-Peace, and the Yukon in North America; the Danube, the Rhine, the Rhône, the Seine, the Po, the Tagus, the Thames, the Loire, the Elbe, the Oder, the Don, the Volga, and the Dnieper in Europe; the Tigris, the Euphrates, the Ob-Irtysh, the Yenisei, the Lena, the Syr Darya, the Amu Darya, the Amur, the Huang He, the Chang (Yangtze), the Ganges, the Brahmaputra, the Indus, the Ayeyarwady, and the Mekong in Asia; and the Murray-Darling in Australia.
Bibliography
See M. Morisawa, Rivers (1985); J. Mangelsdorf, River Morphology (1990).
The activist is not the man who says the river is dirty. The activist is the man who cleans up the river.
— H. Ross Perot
A river is a natural waterway that transits water through a landscape from higher to lower elevations. It is an integral component of the water cycle. The water within a river is generally collected from precipitation through surface runoff, groundwater recharge (as seen at baseflow conditions / during periods of lack of precipitation) and release of stored water in natural reservoirs, such as a glacier.
A river may have its source in a spring, lake, from damp, boggy landscapes where the soil is waterlogged, from glacial melt, or from surface runoff of precipitation. Almost all rivers are joined by other rivers and streams termed tributaries the highest of which are known as headwaters. Water may also originate from groundwater sources. Throughout the course of the river, the total volume transported downstream will often be a combination of the free water flow together with a substantial contribution flowing through sub-surface rocks and gravels that underlie the river and its floodplain (called the hyporheic zone). For many rivers in large valleys, this unseen component of flow may greatly exceed the visible flow.
From their source, all rivers flow downhill, typically terminating in a sea or in a lake, through a confluence. In arid areas rivers sometimes end by losing water to evaporation. River water may also infiltrate into the soil or pervious rock, where it becomes groundwater. Excessive abstraction of water for use in industry, irrigation, etc., can also cause a river to dry before reaching its natural terminus.
The mouth, or lower end, of a river is known by hydrologists as its base level.
The area drained by a river and its tributaries is called catchment, catchment basin, drainage basin or watershed. The term "watershed" is also used to mean a boundary between catchments, which is also called a water divide, or in some cases, continental divide.
The water in a river is usually confined to a channel, made up of a stream bed between banks. In larger rivers there is also a wider flood-plain shaped by flood-waters over-topping the channel. Flood plains may be very wide in relation to the size of the river channel. This distinction between river channel and flood-plain can be blurred especially in urban areas where the flood-plain of a river channel can become greatly developed by housing and industry.
The river channel itself typically contains a single stream of water but some rivers flow as several interconnecting streams of water, producing a braided river. Extensive braided rivers are found in only a few regions worldwide, such as the South Island of New Zealand. They also occur on peneplains and some of the larger river deltas. Anastamosing rivers are similar to braided rivers. They have multiple sinuous channels carrying large volumes of sediment. Due to the dynamics of this type of system, they are also quite rare.
A river flowing in its channel is a source of considerable energy which acts on the river channel to change its shape and form. In mountainous torrential zones this can be seen as erosion channels through hard rocks and the creation of sands and gravels from the destruction of larger rocks. In U shaped glaciated valleys, the subsequent river valley can often easily be identified by the V shaped channel that it has carved. In the middle reaches where the river may flow over flatter land, loops (meanders) may form through eroding of the river banks and deposition on the inside of bends. Sometimes the river will cut off a loop, shortening the channel and forming an oxbow lake or billabong. Rivers that carry large amounts of sediment may develop conspicuous deltas at their mouths, if conditions permit. Rivers, whose mouths are in saline tidal waters, may form estuaries. River mouths may also be fjords or rias.
Although the following classes are a useful simplified way to visualize rivers, it is important to recognize there are other factors at work here. Gradient is controlled largely by tectonics, but discharge is controlled largely by climate and sediment load is controlled by various factors including climate, geology in the headwaters, and the stream gradient.
It has been noted that on average, the air distance (euclidean distance) from the beginning to the end of most rivers is about one third their actual length. For rivers that flow in plain areas, this number is very close to Pi; Einstein wrote an explanation of why this is so.[1][2]
Most rivers flow on the surface, however other rivers may flow underground in caves or caverns. Such rivers can be found in karst regions with limestone geologic formations.
An intermittent river (or ephemeral river) flows occasionally and can be dry for several years at a time. These rivers are found in regions with limited and highly variable rainfall.
Rivers have been used by man since the dawn of civilization as a source of water, for food, for transport, as a defensive barrier, as a source of power to drive machinery, and as a means of disposing of waste.
For thousands of years rivers have been used for navigation (The earliest evidence of navigation is found in the
Indus Valley Civilization, which existed in north-western India around 3300 BC). Riverine navigation provides the cheapest means of transport and is still used
extensively on major rivers of the world like the
In some highly-forested countries like Scandinavia and Canada, lumberjacks use the river to float felled trees downstream to lumber camps for further processing, saving much effort and cost by transporting the huge heavy logs by natural means.
Rivers have been a source of food since pre-history. Apart from being a rich source of fish, rivers indirectly aid cultivation by supplying water for the crops. Rivers sustain their own food chain. They are a major source of fresh water, hence, it is no surprise to find most of the major cities of the world situated on the banks of rivers. Rivers also provide an easy (if unsanitary) means of disposing of waste.
The rocks and gravel generated and moved by rivers have been greatly used in construction. In more recent generations, the beauty of rivers and their wider habitats has contributed greatly to tourist income from areas well endowed with attractive riverine scenery.
In upland rivers, rapids with whitewater or even waterfalls occur. Rapids are often used for recreational purposes (see whitewater kayaking). Fast flowing rivers and waterfalls are harnessed as sources of energy, via watermills and hydroelectric plants.
Rivers have been important historically in determining political boundaries and defending countries. For example, the Danube was a longstanding border of the Roman Empire, and today forms most of the border between Bulgaria and Romania. The Mississippi in North America, and the Rhine in Europe, are major east-west boundaries in those continents. The Orange and Limpopo Rivers in Southern Africa form the boundaries between various provinces and countries along their routes.
The noted Greek historian Megasthenes
(350BC-290BC) mentions about
The flora and fauna of rivers have developed to utilise the very wide range of aquatic habitats available from torrential waterfalls through to lowland mires. Although many organisms are restricted to the fresh-water in rivers, some, such as Salmon and Hilsa have adapted to be able to survive both in rivers and in the sea.
Flooding is a natural part of a river's cycles. The majority of the erosion of river channels and the erosion and deposition on the associated floodplains occur during flood stage. Human activity, however, has upset the natural way flooding occurs by walling off rivers, straightening their courses and by draining of natural wetlands.
Flooding can be mitigated.
A misconception, is that most, or even all, rivers flow from north to south.[3][4] Rivers in fact flow down gradient irrespective of direction, often in a complex meandering path involving all directions of the compass.[5][6][7]
As it happens, few major rivers in the continental US flow north, as most of the country is located in the watershed of the Pacific or Atlantic oceans or the Gulf of Mexico, with very few rivers flowing northward toward the Arctic Ocean, Great Lakes, or Hudson Bay. However, thousands of north-flowing rivers exist elsewhere, including such major watercourses as the Nile, Mackenzie, Rhine, Yenisei, Nelson, and Lena. Four of the ten longest river systems of the world flow mainly north.
Studying the flows of rivers is one aspect of hydrology.[8]
Volumetric flow rate, also called volume flow rate and rate of water flow, is the volume of water which passes through a given volume per unit time, measured in cubic meters per second ( 1 m3/s = 35.51ft3/s).
Rivers are often managed or controlled to make them more useful and less disruptive to human activity.
River management is an ongoing activity as rivers tend to 'undo' the modifications made by man. Dredged channels silt up, sluice mechanisms deteriorate with age, levees and dams may suffer seepage or catastrophic failure. The benefits sought through managing rivers may often be offset by the social and economic costs of mitigating the effects of such management. As an example, in many parts of the developed world, rivers have been confined within channels to free up flat flood-plain land for development. Subsequent extreme flood events can inundate such development at very high financial costs and often with loss of life.
Because rivers are approximately fractal in nature it is difficult to measure the length of a river. The more precise the measurement, the longer the river will seem. Also, it is difficult to determine where a river begins or ends as, very often, upstream rivers are formed by seasonal streams, swamps, or changing lakes. These are average measurements.
Other lists disagree go to: http://www.vaughns-1-pagers.com/geography/longest-rivers.htm
 Río Peralonso - El Zulia (Norte de Santander), Colombia |
 River Gambia flowing through Niokolokoba National Park |
 Bridges are a common way of crossing rivers, as seen here at the Hooghly River, Kolkata, India |
 Zambezi and Victoria Falls (Zambia/Zimbabwe, Africa) |
 This river flows from Woronora Dam, Sydney. |
