In geography, a confluence (also: conflux) occurs where two or more flowing bodies of water join to form a single channel.A confluence can occur in several configurations: at 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 at Pittsburgh, forming the Ohio); or where two separated channels of a river (forming a river island) rejoin at the downstream end.
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 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 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 a confluence can be divided into six distinct featureswhich are commonly called confluence flow zones (CFZ). These include
Since rivers often serve as political boundaries, confluences sometimes demarcate three abutting political entities, such as nations, states, or provinces, forming 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, 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 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.
Occasionally "confluence" is used to describe the meeting of tidal or other non-riverine bodies of water, such as two canals 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.or a canal and a lake. A one-mile (1.6
The term confluence can also apply to the process of merging or flowing together of other substance.For example, it may refer to the merger of the flow of two glaciers.
The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it flows generally south for 2,340 miles (3,770 km) to the Mississippi River Delta in the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains all or parts of 32 U.S. states and two Canadian provinces between the Rocky and Appalachian mountains. The main stem is entirely within the United States; the total drainage basin is 1,151,000 sq mi (2,980,000 km2), of which only about one percent is in Canada. The Mississippi ranks as the thirteenth-largest river by discharge in the world. The river either borders or passes through the states of Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.
The Rhine is one of the major European rivers. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps. It forms part of the Swiss-Liechtenstein, Swiss-Austrian, Swiss-German borders. After that the Rhine defines much of the Franco-German border, after which it flows in a mostly northerly direction through the German Rhineland. Finally in Germany the Rhine turns into a predominantly westerly direction and flows into the Netherlands where it eventually empties into the North Sea. It drains an area of 9,973 sq km and its name derives from the Celtic Rēnos. There are also two German states named after the river, North Rhine-Westphalia and Rhineland-Palatinate.
The Allegheny River is a 325 mi (523 km) long headwater stream of the Ohio River in western Pennsylvania and New York. The Allegheny River runs from its headwaters just below the middle of Pennsylvania's northern border northwesterly into New York then in a zigzag southwesterly across the border and through Western Pennsylvania to join the Monongahela River at the Forks of the Ohio on the "Point" of Point State Park in Downtown Pittsburgh, Pennsylvania. The Allegheny River is, by volume, the main headstream of both the Ohio and Mississippi Rivers. Historically, the Allegheny was considered to be the upper Ohio River by both Native Americans and European settlers.
The Illinois River is a principal tributary of the Mississippi River and is approximately 273 miles (439 km) long. Located in the U.S. state of Illinois, it has a drainage basin of 28,756.6 square miles (74,479 km2). The Illinois River begins at the confluence of the Des Plaines and Kankakee rivers in the Chicago metropolitan area, and it generally flows to the southwest across Illinois, until it empties into the Mississippi near Grafton, Illinois. Its drainage basin extends into southeastern Wisconsin, northwestern Indiana, and a very small area of southwestern Michigan in addition to central Illinois. Along it's shores are several ports, including Peoria, Illinois.
The Maumee River is a river running in the United States Midwest from northeastern Indiana into northwestern Ohio and Lake Erie. It is formed at the confluence of the St. Joseph and St. Marys rivers, where Fort Wayne, Indiana has developed, and meanders northeastwardly for 137 miles (220 km) through an agricultural region of glacial moraines before flowing into the Maumee Bay of Lake Erie. The city of Toledo is located at the mouth of the Maumee. The Maumee was designated an Ohio State Scenic River on July 18, 1974. The Maumee watershed is Ohio’s breadbasket; it is two-thirds farmland, mostly corn and soybeans. It is the largest watershed of any of the rivers feeding the Great Lakes, and supplies five percent of Lake Erie’s water.
The headwaters of a river or stream is the farthest place in that river or stream from its estuary or downstream confluence with another river, as measured along the course of the river. It is also known as a river's source.
The Current River forms in the southeastern portion of the Ozarks of Missouri and becomes a 7th order stream as it flows southeasterly out of the Ozarks into northeastern Arkansas where it becomes a tributary of the Black River, which is a tributary of the White River, a tributary of the Mississippi River. The Current River is approximately 184 miles (296 km) long and drains about 2,641 square miles (6,840 km2) of land mostly in Missouri and a small portion of land in northeastern Arkansas. The headwaters of the Current River are nearly 900 feet (270 m) above sea level, while the mouth of the river lies around 280 feet (85 m) above sea level. The basin drains a rural area that is dominated by karst topography, underlain by dolomite and sandstone bedrock with a small area of igneous rock southeast of Eminence, Missouri. The annual daily mean discharge of the river near Doniphan, Missouri is 2,815 cubic feet (79.7 m3) per second. In 1964, over 134 mi (160 km) of the upper course of the river and its tributaries were federally protected as the Ozark National Scenic Riverways, the first national park in America to protect a river system.
The Boise River is a 102-mile-long (164 km) tributary of the Snake River in the Northwestern United States. It drains a rugged portion of the Sawtooth Range in southwestern Idaho northeast of Boise, as well as part of the western Snake River Plain. The watershed encompasses approximately 4,100 square miles (11,000 km2) of highly diverse habitats, including alpine canyons, forest, rangeland, agricultural lands, and urban areas.
The River Cart is a tributary of the River Clyde, Scotland, which it joins from the west roughly midway between the towns of Erskine and Renfrew and opposite the town of Clydebank.
The Neosho River is a tributary of the Arkansas River in eastern Kansas and northeastern Oklahoma in the United States. Its tributaries also drain portions of Missouri and Arkansas. The river is about 463 miles (745 km) long. Via the Arkansas, it is part of the Mississippi River watershed. Its name is an Osage word meaning "clear water." The lower section is also known as the Grand River.
The Maury River is a 42.8-mile-long (68.9 km) tributary of the James River in west-central Virginia in the United States. It is part of the watershed of Chesapeake Bay.
Side valleys and tributary valleys are valleys whose brooks or rivers flow into greater ones.
River bifurcation occurs when a river flowing in a single stream separates into two or more separate streams which then continue downstream. Some rivers form complex networks of distributaries, typically in their deltas. If the streams eventually merge again or empty into the same body of water, then the bifurcation forms a river island.
Wheeling Creek is a tributary of the Ohio River, 25 miles (40 km) long, in the Northern Panhandle of West Virginia in the United States, with a watershed extending into southwestern Pennsylvania. Via the Ohio River, it is part of the watershed of the Mississippi River, draining an area of approximately 300 square miles (780 km2) on the unglaciated portion of the Allegheny Plateau. It flows into the Ohio River in downtown Wheeling, just downstream of Ohio's Wheeling Creek on the opposite bank. A variant name is Big Wheeling Creek. According to the French explorer Pierre Joseph Céloron de Blainville, the native name of the stream is the Kanououara River, as was inscribed on the lead plate buried at the mouth by the Ohio River in 1749.
Turtle Creek is a 21.1-mile-long (34.0 km) tributary of the Monongahela River in Allegheny and Westmoreland counties in the U.S. state of Pennsylvania. At its juncture with the Monongahela is Braddock, Pennsylvania, where the Battle of the Monongahela was fought in 1755. In the mid-19th century, the Pennsylvania Railroad laid tracks along the stream as part of its Main Line from Philadelphia to Pittsburgh.
A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams are usually called rivers, while smaller, less voluminous and more intermittent streams are known as streamlets, brooks or creeks.
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to using names such as creek, brook, rivulet, and rill. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities a stream is defined 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.
The Anyangcheon is a river in Gyeonggi-do and Seoul, South Korea. It has its source on the slopes of Mount Gwanggyo in the city of Uiwang and flows north, through the city of Gunpo, where a major cleanup operation saw several species of birds return to the area in 2005. Here, though, the water table remains depleted. The river then flows through Anyang City, where it is met by its major tributary, the Hakuicheon stream. From here, it loops around to the west before continuing north to the border with Gwangmyeong City. As the river passes to the west of Mount Gwanak, it forms the border between Gwangmyeong and Seoul, where it is lined on the Gwangmyeong side with rape fields and cherry blossom trees. After the stream is joined near Guil Station from the west by the Mokgamcheon stream, which forms another border between Gwangmyeong and Seoul, it is then totally within the capital. Here, it is also joined from the east by the Dorimcheon and passes through a conservation zone for migratory birds which was established after a 2005 cleanup operation, whereafter it joins the Han. Most of the length of the river has a path alongside providing easy access, the only parts without this lying in Uiwang. Seoul City Council has embarked on a programme of exclusive cycle path creation alongside its waterways, including the Anyangcheon, to be completed in 2010.
North Fork Pacheco Creek is a 19 miles (31 km) tributary stream of Pacheco Creek, in Santa Clara County, California. Originally it was considered the upper reach of Pacheco Creek. Its source is at an elevation of 2,360 feet (720 m) aton a mountain side in Henry W. Coe State Park and is the headwaters of the Pajaro River watershed.
The Rivière du Berger is a tributary of the Saint-Charles River located in Quebec, in the administrative region of Capitale-Nationale, in the province of Quebec, in Canada. It is 18.4 km long.