Misplaced Pages

#441558

26-509: The headwaters arise southwest of the Allen Peak Lookout Tower (at 34°50′47″N 93°28′26″W  /  34.84639°N 93.47389°W  / 34.84639; -93.47389 ) and the stream flows east-northeast. It flows under Arkansas Highway 27 just south of Onyx and then parallel to Arkansas Highway 314 past Steve and Hollis . It passes under Arkansas Route 7 and flows north and east to its confluence with

52-450: A river or stream is the point on each of its tributaries upstream from its mouth / estuary into a lake / sea or its confluence with another river. Each headwater is considered one of the river's sources , as it is the place where surface runoffs from rainwater , meltwater and/or spring water begin accumulating into a more substantial and consistent flow that becomes a first-order tributary of that river. The tributary with

78-602: A tripoint . Various examples are found in the list below. A number of major cities, such as Chongqing , St. Louis , and Khartoum , arose at confluences; further examples appear in the list. Within a city, a confluence often forms a visually prominent point, so that confluences are sometimes chosen as the site of prominent public buildings or monuments, as in Koblenz , Lyon , and Winnipeg . Cities also often build parks at confluences, sometimes as projects of municipal improvement, as at Portland and Pittsburgh . In other cases,

104-414: A confluence can be divided into six distinct features which are commonly called confluence flow zones (CFZ). These include The broader field of engineering encompasses a vast assortment of subjects which concern confluences. In hydraulic civil engineering , where two or more underground culverted / artificially buried watercourses intersect, great attention should be paid to the hydrodynamic aspects of

130-630: A confluence is an industrial site, as in Philadelphia or Mannheim . Often a confluence lies in the shared floodplain of the two rivers and nothing is built on it, for example at Manaus , described below. One other way that confluences may be exploited by humans is as sacred places in religions . Rogers suggests that for the ancient peoples of the Iron Age in northwest Europe, watery locations were often sacred, especially sources and confluences. Pre-Christian Slavic peoples chose confluences as

156-482: A corresponding shift in habitat characteristics." Another science relevant to the study of confluences is chemistry , because sometimes the mixing of the waters of two streams triggers a chemical reaction, particularly in a polluted stream. The United States Geological Survey gives an example: "chemical changes occur when a stream contaminated with acid mine drainage combines with a stream with near-neutral pH water; these reactions happen very rapidly and influence

182-438: Is marshland . The furthest stream is also often called the head stream. Headwaters are often small streams with cool waters because of shade and recently melted ice or snow. They may also be glacial headwaters, waters formed by the melting of glacial ice . Headwater areas are the upstream areas of a watershed , as opposed to the outflow or discharge of a watershed. The river source is often but not always on or quite near

208-415: Is "in a location that is the farthest, along water miles, from where that river ends." Under this definition, neither a lake (excepting lakes with no inflows) nor a confluence of tributaries can be a true river source, though both often provide the starting point for the portion of a river carrying a single name. For example, National Geographic and virtually every other geographic authority and atlas define

234-774: Is used to describe the meeting of tidal or other non-riverine bodies of water, such as two canals or a canal and a lake. A one-mile (1.6 km) portion of the Industrial Canal in New Orleans accommodates the Gulf Intracoastal Waterway and the Mississippi River-Gulf Outlet Canal ; therefore those three waterways are confluent there. The term confluence can also apply to the process of merging or flowing together of other substance. For example, it may refer to

260-491: The river mouth . Confluences are studied in a variety of sciences. Hydrology studies the characteristic flow patterns of confluences and how they give rise to patterns of erosion, bars, and scour pools. The water flows and their consequences are often studied with mathematical models . Confluences are relevant to the distribution of living organisms (i.e., ecology ) as well; "the general pattern [downstream of confluences] of increasing stream flow and decreasing slopes drives

286-652: The Fourche La Fave River east of Nimrod (at 34°57′14″N 93°01′57″W  /  34.95389°N 93.03250°W  / 34.95389; -93.03250 ). The South Fourche LaFave River has a mean annual discharge of 295 cubic feet (8.4 m) per second, according to statistics from the USGS station at Hollis. This article related to a river in Arkansas is a stub . You can help Misplaced Pages by expanding it . Headwaters The headwater of

SECTION 10

#1732790786442

312-543: The USGS at times considers the Missouri River as a tributary of the Mississippi River . But it also follows the first definition above (along with virtually all other geographic authorities and publications) in using the combined Missouri—lower Mississippi length figure in lists of lengths of rivers around the world. Most rivers have numerous tributaries and change names often; it is customary to regard

338-579: The confluence of the Madison and Jefferson rivers, rather than the source of its longest tributary (the Jefferson). This contradicts the most common definition, which is, according to a US Army Corps of Engineers official on a USGS site, that "[geographers] generally follow the longest tributary to identify the source of rivers and streams." In the case of the Missouri River, this would have

364-641: The edge of the watershed, or watershed divide. For example, the source of the Colorado River is at the Continental Divide separating the Atlantic Ocean and Pacific Ocean watersheds of North America . A river is considered a linear geographic feature, with only one mouth and one source. For an example, the Mississippi River and Missouri River sources are officially defined as follows: The verb "rise" can be used to express

390-587: The form of structural bracing. The velocities and hydraulic efficiencies should be meticulously calculated and can be altered by integrating different combinations of geometries, components such a gradients, cascades and an adequate junction angle which is sympathetic to the direction of the watercourse’s flow to minimise turbulent flow, maximise evacuation velocity and to ultimately maximise hydraulic efficiency. Since rivers often serve as political boundaries, confluences sometimes demarcate three abutting political entities, such as nations, states, or provinces, forming

416-435: The general region of a river's source, and is often qualified with an adverbial expression of place. For example: The word "source", when applied to lakes rather than rivers or streams, refers to the lake's inflow . Confluence (geography) In geography , a confluence (also: conflux ) occurs where two or more watercourses join to form a single channel . A confluence can occur in several configurations: at

442-413: The longest course downstream of the headwaters is regarded as the main stem . The United States Geological Survey (USGS) states that a river's "length may be considered to be the distance from the mouth to the most distant headwater source (irrespective of stream name), or from the mouth to the headwaters of the stream commonly known as the source stream". As an example of the second definition above,

468-551: The longest tributary or stem as the source, regardless of what name that watercourse may carry on local maps and in local usage. This most commonly identified definition of a river source specifically uses the most distant point (along watercourses from the river mouth ) in the drainage basin from which water runs year-around ( perennially ), or, alternatively, as the furthest point from which water could possibly flow ephemerally . The latter definition includes sometimes-dry channels and removes any possible definitions that would have

494-545: The point where a tributary joins a larger river ( main stem ); or where two streams meet to become the source of a river of a new name (such as the confluence of the Monongahela and Allegheny rivers, forming the Ohio River ); or where two separated channels of a river (forming a river island ) rejoin at the downstream end. The point of confluence where the channel flows into a larger body of water may be called

520-641: The river changes names numerous times along its course. However, the source of the Thames in England is traditionally reckoned according to the named river Thames rather than its longer tributary, the Churn — although not without contention. When not listing river lengths, however, alternative definitions may be used. The Missouri River's source is named by some USGS and other federal and state agency sources, following Lewis and Clark 's naming convention, as

546-620: The river source "move around" from month to month depending on precipitation or ground water levels. This definition, from geographer Andrew Johnston of the Smithsonian Institution , is also used by the National Geographic Society when pinpointing the source of rivers such as the Amazon or Nile . A definition given by the state of Montana agrees, stating that a river source is never a confluence but

SECTION 20

#1732790786442

572-453: The sites for fortified triangular temples, where they practiced human sacrifice and other sacred rites. In Hinduism , the confluence of two sacred rivers often is a pilgrimage site for ritual bathing. In Pittsburgh, a number of adherents to Mayanism consider their city's confluence to be sacred. Mississippi basin Atlantic watersheds Pacific watersheds Occasionally, "confluence"

598-603: The source be well upstream from Lewis and Clark's confluence, "following the Jefferson River to the Beaverhead River to Red Rock River , then Red Rock Creek to Hell Roaring Creek ." Sometimes the source of the most remote tributary may be in an area that is more marsh -like, in which the "uppermost" or most remote section of the marsh would be the true source. For example, the source of the River Tees

624-639: The source of the Nile River not as Lake Victoria 's outlet where the name "Nile" first appears, which would reduce the Nile's length by over 900 km (560 mi) (dropping it to fourth or fifth on the list of world's rivers), but instead use the source of the largest river flowing into the lake, the Kagera River . Likewise, the source of the Amazon River has been determined this way, even though

650-613: The subsequent transport of metals downstream of the mixing zone." A natural phenomenon at confluences that is obvious even to casual observers is a difference in color between the two streams; see images in this article for several examples. According to Lynch, "the color of each river is determined by many things: type and amount of vegetation in the watershed, geological properties, dissolved chemicals, sediments and biologic content – usually algae ." Lynch also notes that color differences can persist for miles downstream before they finally blend completely. Hydrodynamic behaviour of flow in

676-401: The system to ensure the longevity and efficiency of the structure. Engineers have to design these systems whilst considering a list of factors that ensure the discharge point is structurally stable as the entrance of the lateral culvert into the main structure may compromise the stability of the structure due to the lack of support at the discharge, this often constitutes additional supports in

#441558