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62-533: The Ubangi's length is about 1,060 km (660 mi). Its total length with the Uele, its longest tributary, is 2,270 km (1,410 mi). The Ubangi's drainage basin is about 651,915 km (251,706 sq mi). Mean annual discharge at mouth 5,936 m/s . Its discharge at Bangui ranges from about 800 m/s (28,000 cu ft/s) to 11,000 m/s (390,000 cu ft/s), with an average flow of about ~4,000 m/s (140,000 cu ft/s). It

124-427: A hierarchical pattern . Other terms for a drainage basin are catchment area , catchment basin , drainage area , river basin , water basin , and impluvium . In North America, they are commonly called a watershed , though in other English-speaking places, "watershed" is used only in its original sense, that of the drainage divide line. A drainage basin's boundaries are determined by watershed delineation ,

186-437: A common task in environmental engineering and science. In a closed drainage basin, or endorheic basin , rather than flowing to the ocean, water converges toward the interior of the basin, known as a sink , which may be a permanent lake, a dry lake , or a point where surface water is lost underground . Drainage basins are similar but not identical to hydrologic units , which are drainage areas delineated so as to nest into

248-454: A drainage basin, and there are different ways to interpret that data. In the unlikely event that the gauges are many and evenly distributed over an area of uniform precipitation, using the arithmetic mean method will give good results. In the Thiessen polygon method, the drainage basin is divided into polygons with the rain gauge in the middle of each polygon assumed to be representative for

310-540: A drainage boundary is referred to as watershed delineation . Finding the area and extent of a drainage basin is an important step in many areas of science and engineering. Most of the water that discharges from the basin outlet originated as precipitation falling on the basin. A portion of the water that enters the groundwater system beneath the drainage basin may flow towards the outlet of another drainage basin because groundwater flow directions do not always match those of their overlying drainage network. Measurement of

372-602: A multi-level hierarchical drainage system . Hydrologic units are defined to allow multiple inlets, outlets, or sinks. In a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. About 48.71% of the world's land drains to the Atlantic Ocean . In North America , surface water drains to the Atlantic via the Saint Lawrence River and Great Lakes basins,

434-535: Is 1,344,200 square kilometres (518,998.5 sq mi), of which 839,200 km (324,016.9 sq mi) is in Canada and 505,000 km (194,981.6 sq mi) is in the United States. The basin covers parts of Ontario and Quebec in Canada, parts of Minnesota , Wisconsin , Illinois , Indiana , Ohio , Pennsylvania , New York , Vermont , and nearly the entirety of the state of Michigan in

496-418: Is an area of land in which all flowing surface water converges to a single point, such as a river mouth , or flows into another body of water , such as a lake or ocean . A basin is separated from adjacent basins by a perimeter, the drainage divide , made up of a succession of elevated features, such as ridges and hills . A basin may consist of smaller basins that merge at river confluences , forming

558-720: Is believed that the Ubangi's upper reaches originally flowed into the Chari River and Lake Chad before being captured by the Congo in the early Pleistocene. Together with the Congo River, it provides an important transport artery for river boats between Bangui and Brazzaville . From its source to 100 km (62 mi) below Bangui, the Ubangi defines the boundary between the Central African Republic and

620-487: Is referred to as " watershed management ". In Brazil , the National Policy of Water Resources, regulated by Act n° 9.433 of 1997, establishes the drainage basin as the territorial division of Brazilian water management. When a river basin crosses at least one political border, either a border within a nation or an international boundary, it is identified as a transboundary river . Management of such basins becomes

682-636: Is that country's sixth oldest surviving European place-name. The earliest regular Europeans in the area were the Basques , who came to the St Lawrence Gulf and River in pursuit of whales from the early 16th century. The Basque whalers and fishermen traded with indigenous Americans and set up settlements, leaving vestiges all over the coast of eastern Canada and deep into the St. Lawrence River. Basque commercial and fishing activity reached its peak before

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744-614: Is the Dead Sea . Drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important. For example, the English crown gave the Hudson's Bay Company a monopoly on the fur trade in the entire Hudson Bay basin, an area called Rupert's Land . Bioregional political organization today includes agreements of states (e.g., international treaties and, within

806-524: Is the second longest river in Canada. Lake Champlain and the Ottawa , Richelieu , Saint-Maurice , Saint-François , Chaudière and Saguenay rivers drain into the St. Lawrence. The St. Lawrence River is in a seismically active zone where fault reactivation is believed to occur along late Proterozoic to early Paleozoic normal faults related to the opening of the Iapetus Ocean . The faults in

868-694: The Armada Invencible ' s disaster (1588), when the Basque whaling fleet was confiscated by King Philip II of Spain . Initially, the whaling galleons from Labourd were not affected by the Spanish defeat. Until the early 17th century, the French used the name Rivière du Canada to designate the St. Lawrence upstream to Montreal and the Ottawa River after Montreal. The St. Lawrence River served as

930-713: The African Great Lakes , the interiors of Australia and the Arabian Peninsula , and parts in Mexico and the Andes . Some of these, such as the Great Basin, are not single drainage basins but collections of separate, adjacent closed basins. In endorheic bodies of water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this

992-661: The Champlain Sea , due to a rebounding continent from the Last Glacial Maximum , the St. Lawrence River was formed. The Champlain Sea lasted from about 13,000 years ago to about 10,000 years ago and was continuously shrinking during that time, a process that continues today. The head of the St. Lawrence River, near Lake Ontario, is home to the Thousand Islands . Today, the St. Lawrence River begins at

1054-544: The Eastern Seaboard of the United States, the Canadian Maritimes , and most of Newfoundland and Labrador . Nearly all of South America east of the Andes also drains to the Atlantic, as does most of Western and Central Europe and the greatest portion of western Sub-Saharan Africa , as well as Western Sahara and part of Morocco . The two major mediterranean seas of the world also flow to

1116-711: The Gulf of St. Lawrence : Flowing through and adjacent to numerous Indigenous homelands, the river was a primary thoroughfare for many peoples. Beginning in Dawnland at the Gulf of St. Lawrence, the river borders Mi'kma'ki in the South (what is today known as the Canadian Maritimes ), and Nitassinan in the North, the national territory of the Innu people . On the south shore beyond

1178-507: The Hudson River . The Accommodation with ten passengers made her maiden voyage from Montreal to Quebec City in 66 hours, for 30 of which she was at anchor. She had a keel of 75 feet, and a length overall of 85 feet. The cost of a ticket was eight dollars upstream, and nine dollars down. She had berths that year for twenty passengers. Within a decade, daily service was available in the hotly-contested Montreal-Quebec route. Because of

1240-913: The Mi'kmaw district of Gespe'gewa'ki , the river passes Wolastokuk (the Maliseet homeland), Pαnawαhpskewahki (the Penobscot homeland), and Ndakinna (the Abenaki homeland). Continuing, the river passes through the former country of the St. Lawrence Iroquois and then three of the six homelands of the Haudenosaunee : the Mohawk or Kanienʼkehá꞉ka , the Oneida or Onyota'a:ka , and the Onondaga or Onöñda’gaga’ . In

1302-735: The Mississippi (3.22 million km ), and the Río de la Plata (3.17 million km ). The three rivers that drain the most water, from most to least, are the Amazon, Ganges , and Congo rivers. Endorheic basin are inland basins that do not drain to an ocean. Endorheic basins cover around 18% of the Earth's land. Some endorheic basins drain to an Endorheic lake or Inland sea . Many of these lakes are ephemeral or vary dramatically in size depending on climate and inflow. If water evaporates or infiltrates into

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1364-570: The Mississippi River ) and the 16th-highest in the world. The estuary of St. Lawrence is often cited by scientists as the largest in the world. Significant natural landmarks of the river and estuary include the 1,864 river islands of the Thousand Islands , the endangered whales of Saguenay–St. Lawrence Marine Park , and the limestone monoliths of the Mingan Archipelago . Long a transportation route to Indigenous peoples ,

1426-809: The Nile River ), Southern , Central, and Eastern Europe , Turkey , and the coastal areas of Israel , Lebanon , and Syria . The Arctic Ocean drains most of Western Canada and Northern Canada east of the Continental Divide , northern Alaska and parts of North Dakota , South Dakota , Minnesota , and Montana in the United States, the north shore of the Scandinavian peninsula in Europe, central and northern Russia, and parts of Kazakhstan and Mongolia in Asia , which totals to about 17% of

1488-673: The North Atlantic Ocean . Its waters flow in a northeasterly direction from Lake Ontario to the Gulf of St. Lawrence , traversing Ontario and Quebec in Canada and New York in the United States. A section of the river demarcates the Canada–U.S. border . As the primary drainage outflow of the Great Lakes Basin , the St. Lawrence has the second-highest discharge of any river in North America (after

1550-696: The Thousand Islands chain near Alexandria Bay, New York and Kingston, Ontario ; the Hochelaga Archipelago , including the Island of Montreal and Île Jésus ( Laval ); the Lake St. Pierre Archipelago (classified a biosphere world reserve by the UNESCO in 2000) and the smaller Mingan Archipelago . Other islands include Île d'Orléans near Quebec City and Anticosti Island north of the Gaspé . It

1612-466: The groundwater . A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. Saint Lawrence River The St. Lawrence River ( French : Fleuve Saint-Laurent ) is a large international river in the middle latitudes of North America connecting the Great Lakes to

1674-655: The 16th century, French explorers visited what is now Canada and gave the river names such as the Grand fleuve de Hochelaga and the Grande rivière du Canada , where fleuve and rivière are two French words ( fleuve being a river that flows into the sea). The river's present name has been used since 1604 when it was recorded on a map by Samuel de Champlain Champlain opted for the names Grande riviere de sainct Laurens and Fleuve sainct Laurens in his writings, supplanting

1736-691: The 1980s and 1990s by Nigerian engineer J.   Umolu and the Italian firm Bonifica. In 1994, the Lake Chad Basin Commission (LCBC) proposed a similar project, and at a March 2008 summit the heads of state of the LCBC member countries committed to the diversion project. In April 2008, the LCBC advertised a request for proposals for a feasibility study. 0°30′S 17°42′E  /  0.500°S 17.700°E  / -0.500; 17.700 Drainage basin A drainage basin

1798-789: The Andes. The Indian Ocean 's drainage basin also comprises about 13% of Earth's land. It drains the eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf , the Indian subcontinent , Burma, and most parts of Australia . The five largest river basins (by area), from largest to smallest, are those of the Amazon (7 million km ), the Congo (4 million km ), the Nile (3.4 million km ),

1860-714: The Appalachian division at all. The source of the North River in the Mesabi Range in Minnesota (Seven Beaver Lake) is considered to be the source of the St. Lawrence River. Because it crosses so many lakes, the water system frequently changes its name. From source to mouth, the names are: The St. Lawrence River also passes through Lake Saint-Louis and Lake Saint-Pierre in Quebec. The St. Lawrence River and

1922-675: The Atlantic. The Caribbean Sea and Gulf of Mexico basin includes most of the U.S. interior between the Appalachian and Rocky Mountains , a small part of the Canadian provinces of Alberta and Saskatchewan , eastern Central America , the islands of the Caribbean and the Gulf, and a small part of northern South America. The Mediterranean Sea basin, with the Black Sea , includes much of North Africa , east-central Africa (through

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1984-692: The Democratic Republic of the Congo (DRC). Thereafter, it forms the boundary between the DRC and the Republic of Congo until it empties into the Congo River. In the 1960s, a plan was proposed to divert waters from the Ubangi to the Chari River . According to the plan, named Transaqua, the water from the Ubangi would revitalize Lake Chad and provide a livelihood in fishing and enhanced agriculture to tens of millions of central Africans and Sahelians . Inter-basin water transfer schemes were proposed in

2046-507: The St. Lawrence River has played a key role in the history of Canada and in the development of cities such as Montreal and Quebec City . The river remains an important shipping route as the backbone of the St. Lawrence Seaway , a lock and canal system that enables world marine traffic to access the inland ports of the Great Lakes Waterway . The river has been called a variety of names by local First Nations . Beginning in

2108-406: The St. Lawrence River includes: Large marine mammals travel in all the seas of the earth, the research and observations of these giants concern fishermen and shipping industry , exercise a fascination and a keen interest for laymen and, subjects of endless studies for scientists from Quebec, Canada and around the world. Thirteen species of cetaceans frequent the waters of the estuary and

2170-424: The St. Lawrence to attack the city from the west, which they successfully did at the Battle of the Plains of Abraham . The river was used again by the British to defeat the French siege of Quebec under the Chevalier de Lévis in 1760. In 1809, the first steamboat to ply its trade on the St. Lawrence was built and operated by John Molson and associates, a scant two years after Fulton's steam-powered navigation of

2232-417: The US, interstate compacts ) or other political entities in a particular drainage basin to manage the body or bodies of water into which it drains. Examples of such interstate compacts are the Great Lakes Commission and the Tahoe Regional Planning Agency . In hydrology , the drainage basin is a logical unit of focus for studying the movement of water within the hydrological cycle . The process of finding

2294-554: The United States). The Seaway (including the Welland Canal ) now permits ocean-going vessels to pass all the way to Lake Superior . During the Second World War , the Battle of the St. Lawrence involved submarine and anti-submarine actions throughout the lower St. Lawrence River and the entire Gulf of St. Lawrence , Strait of Belle Isle and Cabot Strait from May to October 1942, September 1943, and again in October and November 1944. During this time, German U-boats sank several merchant marine ships and three Canadian warships. In

2356-523: The United States. The average discharge below the Saguenay River is 16,800 cubic metres per second (590,000 cu ft/s). At Quebec City, it is 12,101 m /s (427,300 cu ft/s). The average discharge at the river's source, the outflow of Lake Ontario, is 7,410 m /s (262,000 cu ft/s). The St. Lawrence River includes Lake Saint Francis at Salaberry-de-Valleyfield , Lake Saint-Louis south of Montreal and Lake Saint Pierre east of Montreal. It encompasses four archipelagoes :

2418-412: The area are rift -related and comprise the Saint Lawrence rift system . According to the United States Geological Survey, the St. Lawrence Valley is a physiographic province of the larger Appalachian division, containing the Champlain section. However, in Canada, where most of the valley is, it is instead considered part of a distinct St. Lawrence Lowlands physiographic division, and not part of

2480-406: The basin, it can form tributaries that change the structure of the land. There are three different main types, which are affected by the rocks and ground underneath. Rock that is quick to erode forms dendritic patterns, and these are seen most often. The two other types of patterns that form are trellis patterns and rectangular patterns. Rain gauge data is used to measure total precipitation over

2542-430: The discharge of water from a basin may be made by a stream gauge located at the basin's outlet. Depending on the conditions of the drainage basin, as rainfall occurs some of it seeps directly into the ground. This water will either remain underground, slowly making its way downhill and eventually reaching the basin, or it will permeate deeper into the soil and consolidate into groundwater aquifers. As water flows through

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2604-441: The drainage area is dependent on the soil type. Certain soil types such as sandy soils are very free-draining, and rainfall on sandy soil is likely to be absorbed by the ground. However, soils containing clay can be almost impermeable and therefore rainfall on clay soils will run off and contribute to flood volumes. After prolonged rainfall even free-draining soils can become saturated , meaning that any further rainfall will reach

2666-642: The drainage basin to the mouth, and may accumulate there, disturbing the natural mineral balance. This can cause eutrophication where plant growth is accelerated by the additional material. Because drainage basins are coherent entities in a hydrological sense, it has become common to manage water resources on the basis of individual basins. In the U.S. state of Minnesota , governmental entities that perform this function are called " watershed districts ". In New Zealand, they are called catchment boards. Comparable community groups based in Ontario, Canada, are called conservation authorities . In North America, this function

2728-424: The earlier names. In contemporary French, the name is rendered as the fleuve Saint-Laurent . The name Saint-Laurent (Saint Lawrence) was originally applied to the eponymous bay by Jacques Cartier upon his arrival into the region on the 10th of August feast day for Saint Lawrence in 1535. Indigenous people use the following names: In winter, the St. Lawrence River begins producing ice in December, with

2790-416: The early 17th century, the Huron-Wendat Nation migrated from their original country of Huronia to what is now known as Nionwentsïo centred around Wendake . Nionwentsïo occupies both the north and south shores of the river, overlapping with Nitassinan and the more western Wabanaki or Dawnland countries. Adjacent on the north shore is the Atikamekw territorial homeland of Nitaskinan and, upstream,

2852-414: The farthest headwater to the mouth and 1,197 km (743.8 mi) from the outflow of Lake Ontario. These numbers include the estuary; without the estuary, the length from Lake Ontario is c. 500 km (c. 300 mi). The farthest headwater is the North River in the Mesabi Range at Hibbing , Minnesota. Its drainage area, which includes the Great Lakes, the world's largest system of freshwater lakes,

2914-408: The formation of ice cubes between Montreal and Quebec City . The prevailing winds and currents push this ice towards the estuary, and it reaches the east of Les Méchins at the end of December. Ice covers the entire Gulf of St. Lawrence in January and February. Ice helps navigation by preventing the formation of waves, and therefore spray, and prevents the icing of ships. With the draining of

2976-415: The further reaches of Anishinaabewaki, specifically the homelands of the Algonquin and Mississauga Nations. The Norse explored the Gulf of St. Lawrence in the 11th century and were followed by fifteenth- and early sixteenth-century European mariners, such as John Cabot , and the brothers Gaspar and Miguel Corte-Real . The first European explorer known to have sailed up the St. Lawrence River itself

3038-435: The ground and along rivers it can pick up nutrients , sediment , and pollutants . With the water, they are transported towards the outlet of the basin, and can affect the ecological processes along the way as well as in the receiving water body . Modern use of artificial fertilizers , containing nitrogen (as nitrates ), phosphorus , and potassium , has affected the mouths of drainage basins. The minerals are carried by

3100-422: The ground at its terminus, the area can go by several names, such playa, salt flat, dry lake , or alkali sink . The largest endorheic basins are in Central Asia , including the Caspian Sea , the Aral Sea , and numerous smaller lakes. Other endorheic regions include the Great Basin in the United States, much of the Sahara Desert , the drainage basin of the Okavango River ( Kalahari Basin ), highlands near

3162-489: The largest tributaries of the Great Lakes . The St. Lawrence River tributaries are listed upstream from the mouth. The major tributaries of the inter-lake sections are also shown, as well as the major rivers that flow into the Great Lakes. Great Lakes tributaries are listed in alphabetical order. The list includes all tributaries with a drainage area of at least 1,000 square kilometres and an average flow of more than 10 cubic metres per second. tributary The diversity of

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3224-399: The main route for European exploration of the North American interior, first pioneered by French explorer Samuel de Champlain . Control of the river was crucial to British strategy to capture New France in the Seven Years' War . Having captured Louisbourg in 1758, the British sailed up to Quebec the following year thanks to charts drawn up by James Cook . British troops were ferried via

3286-488: The outflow of Lake Ontario and flows adjacent to Gananoque , Brockville , Morristown , Ogdensburg , Massena , Cornwall , Montreal , Trois-Rivières , and Quebec City before draining into the Gulf of St. Lawrence , often given as the largest estuary in the world. The estuary begins at the eastern tip of Île d'Orléans , just downstream from Quebec City. The river becomes tidal around Quebec City. The St. Lawrence River runs 3,058 kilometres (1,900  mi ) from

3348-418: The rainfall on the area of land included in its polygon. These polygons are made by drawing lines between gauges, then making perpendicular bisectors of those lines form the polygons. The isohyetal method involves contours of equal precipitation are drawn over the gauges on a map. Calculating the area between these curves and adding up the volume of water is time-consuming. Isochrone maps can be used to show

3410-572: The responsibility of the countries sharing it. Nile Basin Initiative , OMVS for Senegal River , Mekong River Commission are a few examples of arrangements involving management of shared river basins. Management of shared drainage basins is also seen as a way to build lasting peaceful relationships among countries. The catchment is the most significant factor determining the amount or likelihood of flooding . Catchment factors are: topography , shape, size, soil type, and land use (paved or roofed areas). Catchment topography and shape determine

3472-461: The river rather than being absorbed by the ground. If the surface is impermeable the precipitation will create surface run-off which will lead to higher risk of flooding; if the ground is permeable, the precipitation will infiltrate the soil. Land use can contribute to the volume of water reaching the river, in a similar way to clay soils. For example, rainfall on roofs, pavements , and roads will be collected by rivers with almost no absorption into

3534-418: The speed with which the runoff reaches a river. A long thin catchment will take longer to drain than a circular catchment. Size will help determine the amount of water reaching the river, as the larger the catchment the greater the potential for flooding. It is also determined on the basis of length and width of the drainage basin. Soil type will help determine how much water reaches the river. The runoff from

3596-415: The time taken for rain to reach the river, while catchment size, soil type, and development determine the amount of water to reach the river. Generally, topography plays a big part in how fast runoff will reach a river. Rain that falls in steep mountainous areas will reach the primary river in the drainage basin faster than flat or lightly sloping areas (e.g., > 1% gradient). Shape will contribute to

3658-477: The time taken for runoff water within a drainage basin to reach a lake, reservoir or outlet, assuming constant and uniform effective rainfall. Drainage basins are the principal hydrologic unit considered in fluvial geomorphology . A drainage basin is the source for water and sediment that moves from higher elevation through the river system to lower elevations as they reshape the channel forms. Drainage basins are important in ecology . As water flows over

3720-407: The virtually impassable Lachine Rapids , the St. Lawrence was once continuously navigable only as far as Montreal. Opened in 1825, the Lachine Canal was the first to allow ships to pass the rapids. An extensive system of canals and locks, known as the St. Lawrence Seaway , was officially opened on 26 June 1959 by Elizabeth II (representing Canada) and President Dwight D. Eisenhower (representing

3782-468: The world's land. Just over 13% of the land in the world drains to the Pacific Ocean . Its basin includes much of China, eastern and southeastern Russia, Japan, the Korean Peninsula , most of Indochina, Indonesia and Malaysia, the Philippines, all of the Pacific Islands , the northeast coast of Australia , and Canada and the United States west of the Continental Divide (including most of Alaska), as well as western Central America and South America west of

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3844-415: Was Jacques Cartier . At that time, the land along the river described as "about two leagues, a mountain as tall as a heap of wheat" was inhabited by the St. Lawrence Iroquoians . During Cartier's second voyage in 1535, because Cartier arrived in the estuary on Saint Lawrence 's feast day 10 August, he named it the Gulf of Saint Lawrence . The St. Lawrence River is today partly within the U.S. and as such

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