An endorheic basin is a limited drainage basin that retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but converges instead into lakes or swamps, permanent or seasonal, that equilibrate through evaporation. Such a basin may be referred to as a closed or terminal basin or as an internal drainage system or interior drainage basin. Endorheic regions, in contrast to exorheic regions, which flow to the ocean in geologically defined patterns, are closed hydrologic systems, their surface waters drain to inland terminal locations where the water evaporates or seeps into the ground, having no access to discharge into the sea. Endorheic water bodies include some of the largest lakes in the world, such as the Caspian Sea, the world's largest saline inland sea. Endorheic basins constitute local base levels, defining a limit of erosion and deposition processes of nearby areas; the term comes from the Ancient Greek: ἔνδον, éndon, "within" and ῥεῖν, rheîn, "to flow".
Endorheic lakes are bodies of water. Most of the water falling on Earth finds its way to the oceans through a network of rivers and wetlands. However, there is a class of water bodies that are located in closed or endorheic watersheds where the topography prevents their drainage to the oceans; these endorheic watersheds are called terminal lakes or sink lakes. Endorheic lakes are in the interior of a landmass, far from an ocean in areas of low rainfall, their watersheds are confined by natural geologic land formations such as a mountain range, cutting off water egress to the ocean. The inland water flows into dry watersheds where the water evaporates, leaving a high concentration of minerals and other inflow erosion products. Over time this input of erosion products can cause the endorheic lake to become saline. Since the main outflow pathways of these lakes are chiefly through evaporation and seepage, endorheic lakes are more sensitive to environmental pollutant inputs than water bodies that have access to oceans, as pollution can be trapped in them and accumulate over time.
Endorheic regions can occur in any climate but are most found in desert locations. In areas where rainfall is higher, riparian erosion will carve drainage channels, or cause the water level in the terminal lake to rise until it finds an outlet, breaking the enclosed endorheic hydrological system's geographical barrier and opening it to the surrounding terrain; the Black Sea was such a lake, having once been an independent hydrological system before the Mediterranean Sea broke through the terrain separating the two. Lake Bonneville was another such lake; the Malheur/Harney lake system in Oregon is cut off from drainage to the ocean, but has an outflow channel to the Malheur River, dry, but flows in years of peak precipitation. Examples of humid regions in endorheic basins exist at high elevation; these regions are subject to substantial flooding in wet years. The area containing Mexico City is one such case, with annual precipitation of 850 mm and characterized by waterlogged soils that require draining.
Endorheic regions tend to be far inland with their boundaries defined by mountains or other geological features that block their access to oceans. Since the inflowing water can evacuate only through seepage or evaporation, dried minerals or other products collect in the basin making the water saline and making the basin vulnerable to pollution. Continents vary in their concentration of endorheic regions due to conditions of geography and climate. Australia has the highest percentage of endorheic regions at 21 percent while North America has the least at five percent. 18 percent of the earth's land drains to endorheic lakes or seas, the largest of these land areas being the interior of Asia. In deserts, water inflow is low and loss to solar evaporation high, drastically reducing the formation of complete drainage systems. Closed water flow areas lead to the concentration of salts and other minerals in the basin. Minerals leached from the surrounding rocks are deposited in the basin, left behind when the water evaporates.
Thus endorheic basins contain extensive salt pans. These areas tend to be large, flat hardened surfaces and are sometimes used for aviation runways or land speed record attempts, because of their extensive areas of level terrain. Both permanent and seasonal endorheic lakes can form in endorheic basins; some endorheic basins are stable, climate change having reduced precipitation to the degree that a lake no longer forms. Most permanent endorheic lakes change size and shape over time becoming much smaller or breaking into several smaller parts during the dry season; as humans have expanded into uninhabitable desert areas, the river systems that feed many endorheic lakes have been altered by the construction of dams and aqueducts. As a result, many endorheic lakes in developed or developing countries have contracted resulting in increased salinity, higher concentrations of pollutants, the disruption of ecosystems. Within exorheic basins, there can be "non-contributing", low-lying areas that trap runoff and prevent it from contributing to flows downstream during years of average or below-average runoff.
In flat river basins, non-contributing areas can be a large fraction of the river
An ocean is a body of water that composes much of a planet's hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean; these are, in descending order by area, the Pacific, Indian and Arctic Oceans. The word "ocean" is used interchangeably with "sea" in American English. Speaking, a sea is a body of water or enclosed by land, though "the sea" refers to the oceans. Saline water covers 361,000,000 km2 and is customarily divided into several principal oceans and smaller seas, with the ocean covering 71% of Earth's surface and 90% of the Earth's biosphere; the ocean contains 97% of Earth's water, oceanographers have stated that less than 5% of the World Ocean has been explored. The total volume is 1.35 billion cubic kilometers with an average depth of nearly 3,700 meters. As the world ocean is the principal component of Earth's hydrosphere, it is integral to life, forms part of the carbon cycle, influences climate and weather patterns; the World Ocean is the habitat of 230,000 known species, but because much of it is unexplored, the number of species that exist in the ocean is much larger over two million.
The origin of Earth's oceans is unknown. Extraterrestrial oceans may be composed of water or other compounds; the only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their geologic histories and Venus are theorized to have had large water oceans; the Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, a runaway greenhouse effect may have boiled away the global ocean of Venus. Compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of natural satellites; the Solar System's giant planets are thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may exist on exoplanets and exomoons, including surface oceans of liquid water within a circumstellar habitable zone.
Ocean planets are a hypothetical type of planet with a surface covered with liquid. The word ocean comes from the figure in classical antiquity, the elder of the Titans in classical Greek mythology, believed by the ancient Greeks and Romans to be the divine personification of the sea, an enormous river encircling the world; the concept of Ōkeanós has an Indo-European connection. Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases. Though described as several separate oceans, the global, interconnected body of salt water is sometimes referred to as the World Ocean or global ocean; the concept of a continuous body of water with free interchange among its parts is of fundamental importance to oceanography. The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, other criteria.
Oceans are fringed by smaller, adjoining bodies of water such as seas, bays and straits. The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system, part of every ocean and the longest mountain range in the world; the continuous mountain range is 65,000 km long. The total mass of the hydrosphere is about 1.4 quintillion metric tons, about 0.023% of Earth's total mass. Less than 3% is freshwater; the area of the World Ocean is about 361.9 million square kilometers, which covers about 70.9% of Earth's surface, its volume is 1.335 billion cubic kilometers. This can be thought of as a cube of water with an edge length of 1,101 kilometers, its average depth is about 3,688 meters, its maximum depth is 10,994 meters at the Mariana Trench. Nearly half of the world's marine waters are over 3,000 meters deep; the vast expanses of deep ocean cover about 66% of Earth's surface. This does not include seas not connected to the World Ocean, such as the Caspian Sea; the bluish ocean color is a composite of several contributing agents.
Prominent contributors include dissolved organic chlorophyll. Mariners and other seafarers have reported that the ocean emits a visible glow which extends for miles at night. In 2005, scientists announced that for the first time, they had obtained photographic evidence of this glow, it is most caused by bioluminescence. Oceanographers divide the ocean into different vertical zones defined by physical and biological conditions; the pelagic zone includes all open ocean regions, can be divided into further regions categorized by depth and light abundance. The photic zone includes the oceans from the surface to a depth of
A stream is a body of water with surface water flowing within the bed and banks of a channel. The stream encompasses surface and groundwater fluxes that respond to geological, geomorphological and biotic controls. 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 called rivers. Streams are important as conduits in the water cycle, instruments in groundwater recharge, corridors for fish and wildlife migration; the biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction, streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity; the study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography. Brook A stream smaller than a creek one, fed by a spring or seep, it is small and forded. A brook is characterised by its shallowness.
Creek In North America and New Zealand, a small to medium-sized natural stream. Sometimes navigable by motor craft and may be intermittent. In parts of Maryland, New England, the UK and India, a tidal inlet in a salt marsh or mangrove swamp, or between enclosed and drained former salt marshes or swamps. In these cases, the stream is the tidal stream, the course of the seawater through the creek channel at low and high tide. River A large natural stream, which may be a waterway. Runnel the linear channel between the parallel ridges or bars on a shoreline beach or river floodplain, or between a bar and the shore. Called a swale. Tributary A contributory stream, or a stream which does not reach a static body of water such as a lake or ocean, but joins another river. Sometimes called a branch or fork. There are a number of regional names for a stream. Allt is used in Highland Scotland. Beck is used in Lincolnshire to Cumbria in areas which were once occupied by the Danes and Norwegians. Bourne or winterbourne is used in the chalk downland of southern England.
Brook. Burn is used in North East England. Gill or ghyll is seen in Surrey influenced by Old Norse; the variant "ghyll" is used in the Lake District and appears to have been an invention of William Wordsworth. Nant is used in Wales. Rivulet is a term encountered in Victorian era publications. Stream Syke is used in lowland Cumbria for a seasonal stream. Branch is used to name streams in Virginia. Creek is common throughout the United States, as well as Australia. Falls is used to name streams in Maryland, for streams/rivers which have waterfalls on them if such falls have a small vertical drop. Little Gunpowder Falls and The Jones Falls are rivers named in this manner, unique to Maryland. Kill in New York, Pennsylvania and New Jersey comes from a Dutch language word meaning "riverbed" or "water channel", can be used for the UK meaning of'creek'. Run in Ohio, Michigan, New Jersey, Virginia, or West Virginia can be the name of a stream. Run in Florida is the name given to streams coming out of small natural springs.
River is used for larger springs like the Silver Rainbow River. Stream and brook are used in Midwestern states, Mid-Atlantic states, New England. Bar A shoal that develops in a stream as sediment is deposited as the current slows or is impeded by wave action at the confluence. Bifurcation A fork into two or more streams. Channel A depression created by constant erosion. Confluence The point at which the two streams merge. If the two tributaries are of equal size, the confluence may be called a fork. Drainage basin The area of land. A large drainage basin such as the Amazon River contains many smaller drainage basins. Floodplain Lands adjacent to the stream that are subject to flooding when a stream overflows its banks. Gaging station A site along the route of a stream or river, used for reference marking or water monitoring. Headwaters The part of a stream or river proximate to its source; the word is most used in the plural where there is no single point source. Knickpoint The point on a stream's profile where a sudden change in stream gradient occurs.
Mouth The point at which the stream discharges via an estuary or delta, into a static body of water such as a lake or ocean. Pool A segment where the water is deeper and slower moving. Rapids A turbulent, fast-flowing stretch of a stream or river. Riffle A segment where the flow is shallower and more turbulent. River A large natural stream, which may be a waterway. Run A somewhat smoothly flowing segment of the stream. Source The spring, or other point of origin of a stream. Spring The point at which a stream emerges from an underground course through unconsolidated sediments or through caves. A stream can with caves, flow aboveground for part of its course, underground for part of its course. Stream bed The bottom of a stream. Stream corridor Stream, its floodplains, the transitional upland fringe Streamflow The water moving through a stream channel. Thalweg The river's longitudinal section, or the line joining the deepest point in the channel at each stage from source to mouth. Waterfall or cascade The fall of water where the stream goes over a sudden drop called a knickpoint.
The stream expends kinetic energy in "trying" to eliminate the
The Danube is Europe's second longest river, after the Volga. It is located in Eastern Europe; the Danube was once a long-standing frontier of the Roman Empire, today flows through 10 countries, more than any other river in the world. Originating in Germany, the Danube flows southeast for 2,850 km, passing through or bordering Austria, Hungary, Serbia, Bulgaria and Ukraine before draining into the Black Sea, its drainage basin extends into nine more countries. The Danube river basin is home to fish species such as pike, huchen, Wels catfish and tench, it is home to a large diversity of carp and sturgeon, as well as salmon and trout. A few species of euryhaline fish, such as European seabass and eel, inhabit the Danube Delta and the lower portion of the river. Since ancient times, the Danube has become a traditional trade route in Europe, nowadays 2,415 km of its total length being navigable; the river is an important source of energy and drinking water. Danube is an Old European river name derived from a Proto-Indo-European *dānu.
Other river names from the same root include the Dunaj, Dzvina/Daugava, Donets, Dniestr, Dysna and Tuoni. In Rigvedic Sanskrit, dānu means "fluid, drop", in Avestan, the same word means "river". In the Rigveda, Dānu once appears as the mother of Vrtra, "a dragon blocking the course of the rivers"; the Finnish word for Danube is Tonava, most derived from the word for the river in Swedish and German, Donau. Its Sámi name Deatnu means "Great River", it is possible that dānu in Scythian as in Avestan was a generic word for "river": Dnieper and Dniestr, from Danapris and Danastius, are presumed to continue Scythian *dānu apara "far river" and *dānu nazdya- "near river", respectively. The river was known to the ancient Greeks as the Istros a borrowing from a Daco-Thracian name meaning "strong, swift", from a root also encountered in the ancient name of the Dniester and akin to Iranic turos “swift” and Sanskrit iṣiras "swift", from the PIE *isro-, *sreu “to flow”. In the Middle Ages, the Greek Tiras was borrowed into Italian as Tyrlo and into Turkic languages as Tyrla, the latter further borrowed into Romanian as a regionalism.
The Thraco-Phrygian name was Matoas, "the bringer of luck". In Latin, the Danube was variously known as Ister; the Latin name is masculine, except Slovenian. The German Donau is feminine, as it has been re-interpreted as containing the suffix -ouwe "wetland". Romanian differs from other surrounding languages in designating the river with a feminine term, Dunărea; this form was not inherited from Latin. To explain the loss of the Latin name, scholars who suppose that Romanian developed near the large river propose that the Romanian name descends from a hypotetical Thracian *Donaris that shares the same PIE root with the Iranic don-/dan-, with the suffix -aris encountered in the ancient name of the Ialomița River, in the unidentified Miliare river mentioned by Jordanes in his Getica. Gábor Vékony says that this hypothesis is not plausible, because the Greeks borrowed the Istros form from the native Thracians, he proposes. The modern languages spoken in the Danube basin all use names related to Dānuvius: German: Donau.
Dunav. Dunai. Classified as an international waterway, it originates in the town of Donaueschingen, in the Black Forest of Germany, at the confluence of the rivers Brigach and Breg; the Danube flows southeast for about 2,730 km, passing through four capital cities before emptying into the Black Sea via the Danube Delta in Romania and Ukraine. Once a long-standing frontier of the Roman Empire, the river passes through or touches the borders of 10 countries: Romania, Serbia, Germany, Slovakia, Croatia and Moldova, its drainage basin extends into nine more. In addition to the bordering countries, the drainage basin includes parts of nine more countries: Bosnia and Herzegovina, the Czech Republic, Montenegro, Italy, North Macedonia and Albania, its total drainage basin is 801,463 km2. The highest point of the drainage basin is the summit of Piz Bernina at the Italy–Switzerland border, at 4,049 metres; the land drained by the Danube extends into many other countries. Many Danubian tributaries are important rivers in their own right, navigable by barges and other shallow-draught boats.
From its source to its outlet into the Black Sea, its main tribu
Continental Divide of the Americas
The Continental Divide is the principal, mountainous, hydrological divide of the Americas. The Continental Divide extends from the Bering Strait to the Strait of Magellan, separates the watersheds that drain into the Pacific Ocean from those river systems that drain into the Atlantic Ocean and, along the northernmost reaches of the Divide, those river systems that drain into the Arctic Ocean. Though there are a few other hydrological divides in the Americas, the Continental Divide is by far the most prominent of these because it tends to follow a line of high peaks along the main ranges of the Rocky Mountains and Andes, at a much higher elevation than the other hydrological divisions; the Continental Divide begins at Cape Prince of Wales, the westernmost point on the mainland of the Americas. The Divide crosses northern Alaska into the Yukon zig-zags south into British Columbia via the Cassiar Mountains and Omineca Mountains and northern Nechako Plateau to Summit Lake, north of the city of Prince George and just south of the community of McLeod Lake.
From there the Divide traverses the McGregor Plateau to the spine of the Rockies, following the crest of the Canadian Rockies southeast to the 120th meridian west, from there forming the boundary between southern British Columbia and southern Alberta. The Divide crosses into the United States in northwestern Montana, at the boundary between Waterton Lakes National Park and Glacier National Park. In Canada, it forms the western boundary of Waterton Lakes National Park, in the US bisects Glacier National Park. Further south, the Divide forms the backbone of the Rocky Mountain Front in the Bob Marshall Wilderness, heads south towards Helena and Butte west past the namesake community of Divide, through the Anaconda-Pintler Wilderness to the Bitterroot Range, where it forms the eastern third of the state boundary between Idaho and Montana; the Divide crosses into Wyoming within Yellowstone National Park and continues southeast into Colorado where it reaches its highest point in North America at the summit of Grays Peak at 4,352 m.
It crosses US Hwy 160 in southwestern Colorado at Wolf Creek Pass, where a line symbolizes the division. The Divide proceeds south into western New Mexico, passing along the western boundary of the endorheic Plains of San Agustin. Although the Divide represents the height of land between watersheds, it does not always follow the highest ranges/peaks within each state or province. In Mexico, it passes through Chihuahua, Zacatecas, Jalisco, Querétaro, México, the Federal District, Puebla and Chiapas. In Central America, it continues through southern Guatemala, southwestern Honduras, western Nicaragua, western/southwestern Costa Rica, southern Panama; the divide reaches its lowest natural point in Central America at the Isthmus of Rivas at 47 m in Nicaragua. In Panama, the Canal cuts through it at 85 ft; the Divide continues into South America, where it follows the peaks of the Andes Mountains, traversing western Colombia, central Ecuador and southwestern Peru, eastern Chile, southward to the southern end of Patagonia and Tierra del Fuego.
In North America, another non-mountainous divide, the Laurentian Divide, further separates the Hudson Bay-Arctic Ocean drainage region from the Atlantic watershed region. Secondary divides separate the watersheds that flow into the Great Lakes and Saint Lawrence River from watersheds that flow to the Atlantic via the Missouri-Mississippi complex. Another secondary divide follows the Appalachian chain, which separates those streams and rivers that flow directly into the Atlantic Ocean from those that exit via the Mississippi River. Triple Divide Peak in Glacier National Park, Montana, is the point where two of the principal continental divides in North America converge, the primary Continental Divide and the Northern or Laurentian Divide. From this point, waters flow to the Pacific Ocean, the Atlantic Ocean via the Gulf of Mexico, the Arctic Ocean via Hudson Bay. Most geographers, geologists and oceanographers consider this point the hydrological apex of North America, as Hudson Bay is considered part of the Arctic.
For example, the International Hydrographic Organization defines the Hudson Bay, with its outlet extending from 62.5 to 66.5 degrees north as being part of the Arctic Ocean "Arctic Ocean Subdivision 9.11." This hydrological apex of North America status of Triple Divide Peak is the main reason behind the designation of Waterton-Glacier International Peace Park as the "Crown of the Continent" of North America. The summit of the peak is the world's only oceanic triple divide point. Discounting Antarctica and its ice sheets, only one other continent borders three oceans, but the inward-draining Endorheic basin area of Central Asia from western China to the Aral and Caspian Seas is so vast that any Arctic and Indian Ocean tributaries are never within proximity of each other. Thus, North America's status of having a single location draining into three oceans is unique in the world. Sources differ, however, on whether Hudson Bay south of the Arctic Circle, is part of the Atlantic or Arctic Ocean. Hudson Bay's water budget connects to the Atlantic more than to the Arctic Ocean.
Saskatchewan is a prairie and boreal province in western Canada, the only province without a natural border. It has an area of 651,900 square kilometres, nearly 10 percent of, fresh water, composed of rivers and the province's 100,000 lakes. Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, on the south by the U. S. states of North Dakota. As of late 2018, Saskatchewan's population was estimated at 1,165,903. Residents live in the southern prairie half of the province, while the northern boreal half is forested and sparsely populated. Of the total population half live in the province's largest city Saskatoon, or the provincial capital Regina. Other notable cities include Prince Albert, Moose Jaw, Swift Current, North Battleford and the border city Lloydminster. Saskatchewan is a landlocked province with large distances to moderating bodies of waters; as a result, its climate is continental, rendering severe winters throughout the province.
Southern areas have warm or hot summers. Midale and Yellow Grass near the U. S. border are tied for the highest recorded temperatures in Canada with 45 °C observed at both locations on July 5, 1937. In winter, temperatures below −45 °C are possible in the south during extreme cold snaps. Saskatchewan has been inhabited for thousands of years by various indigenous groups, first explored by Europeans in 1690 and settled in 1774, it became a province in 1905, carved out from the vast North-West Territories, which had until included most of the Canadian Prairies. In the early 20th century the province became known as a stronghold for Canadian social democracy; the province's economy is based on agriculture and energy. Saskatchewan's current lieutenant governor is the current premier is Scott Moe. In 1992, the federal and provincial governments signed a historic land claim agreement with First Nations in Saskatchewan; the First Nations received compensation and were permitted to buy land on the open market for the bands.
Some First Nations have used their settlement to invest in urban areas, including Saskatoon. Its name derived from the Saskatchewan River; the river was known as kisiskāciwani-sīpiy in the Cree language. As Saskatchewan's borders follow the geographic coordinates of longitude and latitude, the province is a quadrilateral, or a shape with four sides. However, the 49th parallel boundary and the 60th northern border appear curved on globes and many maps. Additionally, the eastern boundary of the province is crooked rather than following a line of longitude, as correction lines were devised by surveyors prior to the homestead program. Saskatchewan is part of the Western Provinces and is bounded on the west by Alberta, on the north by the Northwest Territories, on the north-east by Nunavut, on the east by Manitoba, on the south by the U. S. states of North Dakota. Saskatchewan has the distinction of being the only Canadian province for which no borders correspond to physical geographic features. Along with Alberta, Saskatchewan is one of only two land-locked provinces.
The overwhelming majority of Saskatchewan's population is located in the southern third of the province, south of the 53rd parallel. Saskatchewan contains two major natural regions: the Boreal Forest in the north and the Prairies in the south, they are separated by an aspen parkland transition zone near the North Saskatchewan River on the western side of the province, near to south of the Saskatchewan River on the eastern side. Northern Saskatchewan is covered by forest except for the Lake Athabasca Sand Dunes, the largest active sand dunes in the world north of 58°, adjacent to the southern shore of Lake Athabasca. Southern Saskatchewan contains another area with sand dunes known as the "Great Sand Hills" covering over 300 square kilometres; the Cypress Hills, located in the southwestern corner of Saskatchewan and Killdeer Badlands, are areas of the province that were unglaciated during the last glaciation period, the Wisconsin glaciation. The province's highest point, at 1,392 metres, is located in the Cypress Hills less than 2 km from the provincial boundary with Alberta.
The lowest point is the shore of Lake Athabasca, at 213 metres. The province has 14 major drainage basins made up of various rivers and watersheds draining into the Arctic Ocean, Hudson Bay and the Gulf of Mexico. Saskatchewan receives more hours of sunshine than any other Canadian province; the province lies far from any significant body of water. This fact, combined with its northerly latitude, gives it a warm summer, corresponding to its humid continental climate in the central and most of the eastern parts of the province, as well as the Cypress Hills. Drought can affect agricultural areas during no precipitation at all; the northern parts of Saskatchewan – from about La Ronge northward – have a subarctic climate with a shorter summer season. Summers can get hot, sometimes above 38 °C during the day, with humidity decreasing from northeast to southwest. Warm southern winds blow from the plains and intermontane regions of
The Mackenzie River is the longest river system in Canada, has the second largest drainage basin of any North American river after the Mississippi River. The Mackenzie River flows through a vast, thinly populated region of forest and tundra within the Canadian Northwest Territories, although its many tributaries reach into four other Canadian provinces and territories; the river's main stem is 1,738 kilometres long, flowing north-northwest from Great Slave Lake into the Arctic Ocean, where it forms a large delta at its mouth. Its extensive watershed drains about 20 percent of Canada, it is the largest river flowing into the Arctic from North America, including its tributaries has a total length of 4,241 kilometres, making it the thirteenth longest river system in the world. Through its many tributaries, the Mackenzie River basin covers portions of five Canadian provinces and territories – British Columbia, Saskatchewan and Northwest Territories. Thutade Lake, in the Northern Interior of BC, is the ultimate source of the Mackenzie River via the Finlay–Peace River system, which stretches 1,923 kilometres through BC and Alberta.
The 1,231-kilometre Athabasca River originates further south, in Jasper National Park in southwest Alberta. Together, the Peace and Athabasca rivers drain a significant portion of the eastern slope of the Rocky Mountains and the central Alberta prairie; the Peace contributes the majority of the water, about 66 km3 per year, the Athabasca contributes 25 km3. The Peace and Athabasca meet at the Peace-Athabasca Delta, a vast inland delta at the western end of Lake Athabasca, which takes runoff from the northern third of Saskatchewan; the Slave River is formed by the confluence of the two rivers and flows 415 kilometres due north into Great Slave Lake, at Fort Resolution, Northwest Territories. The Slave is by far the largest river flowing into the lake, with an annual flow of 108 km3, it contributes about 77% of the overall inflow, forms a large delta where it enters the lake. Other rivers entering Great Slave Lake area the Taltson and Hay Rivers, the latter of which extends into Alberta and BC.
The Mackenzie River issues from the western end of Great Slave Lake about 150 km south-west of Yellowknife. The channel is several kilometres wide but narrows to about 800 m at Fort Providence, an important ferry crossing in the summer, used as an ice bridge in the winter for traffic along the Yellowknife Highway. In 2012 the Deh Cho Bridge was completed at a point about 10 km upstream, providing a safer permanent crossing, it is the only bridge across the main stem of the Mackenzie. West of Fort Providence the Mackenzie widens resembling a shallow, swampy lake more than a river. After heading west for about 100 km the Mackenzie narrows and turns northwest through a long stretch of fast water and rapids, past the village of Jean Marie River. At Fort Simpson it is joined by its biggest direct tributary, from the west; the Liard drains a large area in the southern Yukon and northern BC and carries a large amount of sediment during the summer melt – which does not mix with the clear water in the Mackenzie for 500 km downstream, with the resulting phenomenon of a clear current on the east bank and muddy water on the west bank.
The river continues west-northwest until its confluence with the North Nahanni River, where it turns north towards the Arctic. It flows through open taiga with its wide valley bounded, on the west, by the Mackenzie Mountains and to the east by low hills of the Canadian Shield; this uninhabited area is called the Mackenzie Lowlands. A number of major tributaries join from the west, including the Root River, Redstone River and Keele River. Below the Keele River, the Mackenzie River flows north along the western base of the Franklin Mountains before turning northwest, receives the Great Bear River, the outflow of Great Bear Lake at Tulita; the Mackenzie widens to about 6 to 7 km at Norman Wells, a major center of oil production. There is a narrows at the Mountain River confluence called the Sans Sault Rapids, where the Mackenzie falls about 6 metres. Below the Mountain River the Mackenzie flows due north until reaching The Ramparts, a limestone gorge 500 metres wide and up to 45 metres deep. Below The Ramparts is the village of Fort Good Hope, where the Mackenzie turns northwest again, soon crossing the Arctic Circle.
The Mackenzie here flows lower in elevation than the surrounding tundra, as a braided river between low bluffs about 3 to 5 km apart. It receives the Arctic Red River from the southwest at Tsiigehtchic, where traffic on the Dempster Highway crosses via ferry/ice bridge. About 30 kilometres northwest of Tsiigehtchic is Point Separation, the head of the vast Mackenzie River Delta, whose branching channels and wetlands spread across more than 12,000 square kilometres of the coastal plain; the delta is nearly 210 km from north to south, ranges in width from 50 to 80 km. It is the second biggest Arctic delta in the world, after the Lena River delta in Russia. Most land in the Mackenzie delta consists with great depths to bedrock. A characteristic feature of the delta is its numerous pingos, or hill