An endorheic basin (also endoreic basin or endorreic basin) is a limited drainage basin that normally 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 also 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.
The term comes from the Ancient Greek: ἔνδον, éndon, "within" and ῥεῖν, rheîn, "to flow".
Endorheic lakes are bodies of water that do not flow into the sea. Most of the water falling on Earth finds its way to the oceans through a network of rivers, lakes 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 (containing water in rivers or lakes that form a balance of surface inflows, evaporation and seepage) are often called terminal lakes or sink lakes.
Endorheic lakes are usually in the interior of a landmass, far from an ocean in areas of relatively low rainfall. Their watersheds are often 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 relatively saline (a "salt lake"). Since the main outflow pathways of these lakes are chiefly through evaporation and seepage, endorheic lakes are usually 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 commonly found in desert locations. In areas where rainfall is higher, riparian erosion will generally carve drainage channels (particularly in times of flood), 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 likely 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, overflowing its basin in the Bonneville flood. The Malheur/Harney lake system in Oregon is normally cut off from drainage to the ocean, but has an outflow channel to the Malheur River that is normally dry, but flows in years of peak precipitation.
Examples of relatively humid regions in endorheic basins often exist at high elevation. These regions tend to be marshy and are subject to substantial flooding in wet years. The area containing Mexico City is one such case, with annual precipitation of 850 mm (33 in) 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, eventually making the water saline and also 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. Approximately 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 often lead to the concentration of salts and other minerals in the basin. Minerals leached from the surrounding rocks are deposited in the basin, and left behind when the water evaporates. Thus endorheic basins often contain extensive salt pans (also called salt flats, salt lakes, alkali flats, dry lake beds or playas). 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 perfectly level terrain.
Both permanent and seasonal endorheic lakes can form in endorheic basins. Some endorheic basins are essentially stable, climate change having reduced precipitation to the degree that a lake no longer forms. Even most permanent endorheic lakes change size and shape dramatically over time, often becoming much smaller or breaking into several smaller parts during the dry season. As humans have expanded into previously 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 dramatically, resulting in increased salinity, higher concentrations of pollutants, and the disruption of ecosystems.
Even 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 basin, e.g. Lake Winnipeg's basin. A lake may be endorheic during dry years and can overflow its basin during wet years, e.g., the former Tulare Lake.
Because the Earth's climate has recently been through a warming and drying phase with the end of the Ice Ages, many endorheic areas such as Death Valley that are now dry deserts were large lakes relatively recently. During the last ice age, the Sahara may have contained lakes larger than any now existing.
Other endorheic lakes and basins in Asia include:
Australia, being very dry and having exceedingly low runoff ratios due to its ancient soils, has many endorheic drainages. The most important are:
Though a large portion of Europe drains to the endorheic Caspian Sea, Europe's wet climate means it contains relatively few terminal lakes itself: any such basin is likely to continue to fill until it reaches an overflow level connecting it with an outlet or erodes the barrier blocking its exit. Exceptions include:
All these lakes are drained, however, either through manmade canals or via karstic phenomena. Minor endorheic lakes exist throughout the Mediterranean countries of Spain (e.g. Laguna de Gallocanta, Estany de Banyoles), Italy, Cyprus (Larnaca and Akrotiri salt lakes) and Greece.
Some of the Earth's ancient endorheic systems and lakes include:
Badwater Basin is an endorheic basin in Death Valley National Park, Death Valley, Inyo County, California, noted as the lowest point in North America, with a depth of 282 ft (86 m) below sea level. Mount Whitney, the highest point in the contiguous 48 United States, is only 84.6 miles (136 km) to the northwest.The site itself consists of a small spring-fed pool of "bad water" next to the road in a sink; the accumulated salts of the surrounding basin make it undrinkable, thus giving it the name. The pool does have animal and plant life, including pickleweed, aquatic insects, and the Badwater snail.
Adjacent to the pool, where water is not always present at the surface, repeated freeze–thaw and evaporation cycles gradually push the thin salt crust into hexagonal honeycomb shapes.
The pool is not the lowest point of the basin: the lowest point (which is only slightly lower) is several miles to the west and varies in position, depending on rainfall and evaporation patterns. The salt flats are hazardous to traverse (in many cases being only a thin white crust over mud), and so the sign marking the low point is at the pool instead. The basin was considered the lowest elevation in the Western Hemisphere until the discovery of Laguna del Carbón in Argentina at −344 ft (−105 m).Chakhansur District
Chakhansur (Persian: چخانسور) is a district in the Nimruz Province of Afghanistan. It has a population of about 11,165 as of 2004, which includes Pashtun, Tajik, Baloch and Hazara ethnic groups.The economy is primarily based on agriculture, and the necessary water for irrigation is dependent on the status of the Sistan Basin, an endorheic basin which periodically becomes dry.
This area of Afghanistan was a major medieval cultural hub on the Silk Road but most ancient structures are now covered by sand. Signs of historical irrigation systems, including canals, are still visible in the Chakhansur area while elsewhere canals are filled with silt and agricultural fields buried by shifting sand. Today the area is relatively sparsely populated. There continue to be problems with water control and periodic flooding and drought.Currently the Chakhansur farmers are experiencing a severe and long term drought. Even with help from the World Food Program, many have abandoned their homes, perhaps as many as 20,000, to search for water and jobs.Continental divide
A continental divide is a drainage divide on a continent such that the drainage basin on one side of the divide feeds into one ocean or sea, and the basin on the other side either feeds into a different ocean or sea, or else is endorheic, not connected to the open sea. Every continent on earth except Antarctica which has no free-flowing water has at least one continental drainage divide; islands, even small ones like Killiniq Island on the Labrador Sea in Canada, may also host part of a continental divide or have their own island-spanning divide.
The endpoints of a continental divide may be coastlines of gulfs, seas or oceans, the boundary of an endorheic basin, or another continental divide. One case, the Great Basin Divide, is a closed loop around an endoreic basin. The endpoints where a continental divide meets the coast are not always definite since the exact border between adjacent bodies of water is usually not clearly defined. The International Hydrographic Organization's publication Limits of Oceans and Seas defines exact boundaries of oceans, but it is not universally recognized. Where a continental divide meets an endorheic basin, such as the Great Divide Basin of Wyoming, the continental divide splits and encircles the basin. Where two divides intersect, they form a triple divide, where three watersheds meet.
Whether a divide is considered a continental divide distinguished from other secondary drainage divides may depend on whether the associated gulfs, seas, or oceans are considered separate. For example, the Gulf of Mexico is considered separate from the Atlantic Ocean, so the Eastern Continental Divide separates their respective watersheds. But the Sea of Cortez is usually not considered separate from the Pacific Ocean, so the divide between the Colorado River watershed which drains to the Sea of Cortez, and Columbia River Watershed which drains to the Pacific Ocean, is not considered to be a continental divide.
Together, continental divides demarcate a set of drainage basins or watersheds, each of which drains to a specific ocean, sea or gulf, such as the North American Atlantic seaboard watershed which is demarcated by the Eastern Continental Divide and Great Lakes-St. Lawrence Divide.Ebro Basin
The Ebro Basin was a foreland basin that formed to the south of the Pyrenees during the Paleogene. It was also limited to the southeast by the Catalan Coastal Ranges. It began as a fully marine basin with connections to both the Atlantic Ocean and the Mediterranean Sea, before becoming an endorheic basin during the Late Eocene. In the Miocene the basin was captured by a precursor to the Ebro river and the new drainage system that developed eroded away much of the basin fill, except for resistant lithologies, such as the conglomerates at Montserrat.Lake Acıgöl
Acıgöl (literally "the bitter lake" in Turkish) is a lake in Turkey's inner Aegean Region, in an endorheic basin at the junction between Denizli Province, Afyonkarahisar Province and Burdur Province. Its surface area varies greatly through the seasons, with 100 km² in spring and 35 km² in late summer, with a maximum depth of 1.63 m. The lake is notable for its sodium sulfate reserves extensively used in the industry and Turkey's largest commercial sodium sulfate production operations are based here. It is situated 60 km east of Denizli city. The lake's surrounding districts and towns are, from west to east, Bozkurt, Çardak, Dazkırı and Başmakçı.
The lake's altitude is 836 m and it is fed primarily by high-sulfate springs issuing from a fault line on its south side. The lake is estimated to contain 12.5 million mt of sodium sulfate in the surface and in the subsurface brine, with probable total reserves of 70 million mt, and possible reserves of 82 million mt. The yearly production rate in late 1990s was 100,000 tonnes, all operated by private sector companies.Lake Cuitzeo
Lake Cuitzeo(Spanish [kwitse'o] ) is a lake in the central part of Mexico, in the state of Michoacán. It has an area of 300–400 km2 (120–150 sq mi). The lake is astatic, meaning the volume and level of water in the lake fluctuates frequently. It is the second-largest freshwater lake in Mexico.Lake Cuitzeo lies in an endorheic basin, which does not drain to the sea. The basin has an area of 4,026 km2 (1,554 sq mi), lying mostly in Michoacán, with the northern part of the basin in Guanajuato state. Michoacán's capital, Morelia, lies in the Cuitzeo basin south of the lake. The basin of the Lerma River lies to the east and north, and the basin of the Balsas River lies to the south, separated by the mountains of the Trans-Mexican Volcanic Belt. The endorheic basin of Lake Pátzcuaro lies to the west.
The lake is irregular in shape, with northern, western, and eastern sections connected by a central marshy area, which receives the main freshwater inflows. It has no natural outflow, but an outflow canal was constructed to the north, allowing the lake to drain into the Lerma River basin when the water level is high. The western section was divided in two by the construction of north-south highways. The western portion is saltier, and sustains unusual fisheries of clam shrimps (Eocyzicus digueti and Leptestheria compleximanus), as well as hemipterans, and ephydrids. The lake basin is the only habitat for Thamnophis eques cuitzeoensis, a subspecies of the essentially harmless, semi-aquatic Mexican garter snake.The three main inflows to the lake are the Viejo de Morelia, Grande de Morelia, and Querendaro rivers. These rivers originate in the mountains to the south, and sustain an irrigated agricultural area south of the lake, entering the central portion of the lake as irrigation canals. The main crops are maize, cotton, and coffee.About 40 percent of the basin is agricultural fields, 15 percent is pasture, 20 percent is pine-oak forests, and 15 percent is tropical dry forest. The pine-oak forests lie at higher elevations, and are part of the Trans-Mexican Volcanic Belt pine-oak forests ecoregion. The Bajío dry forests ecoregion covers the lower-lying parts of the basin, extending north into the basin of the Lerma River.List of drainage basins by area
The list of drainage basins by area identifies basins (also known as "catchments" or, in North American usage, "watersheds"), sorted by area, which drain to oceans, mediterranean seas, rivers, lakes and other water bodies. All basins larger than 400,000 km2 (150,000 sq mi) are included as well as selected smaller basins. It includes drainage basins which do not flow to the ocean (endorheic basins). It includes oceanic sea drainage basins which have hydrologically coherent areas (oceanic seas are set by IHO convention).
The oceans drain approximately 83% of the land in the world. The other 17% – an area larger than the basin of the Arctic Ocean – drains to internal endorheic basins.
Note that there are substantial areas of the world that do not "drain" in the commonly understood sense. In Arctic deserts much of the snowfall sublimates directly into the air and does not melt into flowing water, while in equatorial deserts precipitation may evaporate before joining any substantial water course. However, these areas can still be included in topographically defined basins if one considers the hypothetical flow of water (or ice), and thus nutrients or pollutants, over the surface of the ground (or ice sheet); this is the approach taken here. For example, the Antarctic ice sheet can be divided into basins, and most of Libya is included in the Mediterranean Sea basin even though almost no water from the interior actually reaches the sea.List of lakes in California
There are more than 3,000 named lakes, reservoirs, and dry lakes in the U.S. state of California.List of lakes of Kazakhstan
Most of Kazakhstan is endorheic basin (except northern territories). As it is expected, the rivers flow into the numerous lakes in the basin. The most important drainage system is known as Yedisu, meaning "seven rivers" in Turkic languages. Below is the list of more important lakes. Some of these lakes are shared with the neighbouring countries. (Caspian Sea, Lake Aral, Lake Aike, etc.)List of rivers of Azerbaijan
This is a list of rivers of Azerbaijan. The hydrography of Azerbaijan basically belongs to the Caspian Sea drainage basin to which all rivers in Azerbaijan flow to.The Caspian Sea is an endorheic basin, which is a closed drainage basin, because the Caspian Sea has no outflows to an ocean.The longest river of the Republic of Azerbaijan is the Kur whose river source is in Turkey and which flows through the Republic of Georgia, before it enters Azerbaijan. There it unites with the second longest river Aras whose river source is also in Turkey, and which is on the country's border with Iran. The major tributaries of the Kur river are the Qanix, Qabirri, Turyan, Agstafa, Shekir, Terter and Khachin rivers. The major tributaries of the Aras river are the Arpachay, Nakhchivan, Okhchu, Hekeri and Kondelenchay rivers. The largest rivers which are not tributaries of the Kur and Aras rivers are the Samur, Gudyal, Velvele, Vilesh and Lenkeran rivers.List of rivers of El Salvador
This is a list of rivers in El Salvador.
El Salvador has 58 river basins which all drain to the Pacific Ocean. The total amount of water discharged into the Pacific is 19 million m³ in a normal year.
Additionally, there are several endorheic basins linked to a lake. Coatepeque Lake is the largest endorheic basin in the country.Morongo Basin
The Morongo Basin is an endorheic basin and valley region located in eastern San Bernardino County, in Southern California.
The Morongo basin is part of the Inland Empire region, and is considered to be the easternmost portion of the Greater Los Angeles Area, the 2nd largest metropolitan region in the United States.Shule River
The Shule River flows generally westwards through the Tibetan Plateau and the desert regions of northwestern China. It starts in the Qilian Mountains and stretches for some 900 kilometres (560 mi); however, the river dries up about two-thirds of the way along its course and is lost in the Kumtag Desert, an endorheic basin, meaning its water never reaches the sea. Historically, the river reached farther west to Lop Nur, an intermittent salt lake in the Taklimakan Desert. Large irrigation diversions off the river and the gradual desertification of the region have reduced its flow significantly.Sink (geography)
A geographic sink is a depression within an endorheic basin where water collects with no visible outlet. Instead of discharging, the collected water is lost due to evaporation and/or penetration (water sinking underground, e.g., to become groundwater in an aquifer). If the sink has karstic terrain, water will sink at a higher rate than the surface evaporation, and conversely if the lakebed or sink bed has a layer of soil that is largely impervious to water (hardpan), evaporation will predominate. Since dry lakes in sinks with hardpan have little penetration, they require more severe aridity/heat to eliminate collected water at a comparable rate as for a similar sink with appreciable penetration.
Depending on losses, precipitation, and inflow (e.g., a spring, a tributary, or flooding); the temporal result of a lake in a sink may be a persistent lake, an intermittent lake, a playa lake (temporarily covered with water), or an ephemeral lake.Sistan Basin
The Sistan Basin is an inland endorheic basin encompassing large parts of southwestern Afghanistan and minor parts of southeastern Iran, one of the driest regions in the world and an area subjected to prolonged droughts. Its watershed is a system of rivers flowing from the highlands of Afghanistan into freshwater lakes and marshes and then to its ultimate destination: Afghanistan's saline Godzareh depression, part of the extensive Sistan terminal basin. The Helmand River drains the basin's largest watershed, fed mainly by snowmelt from the mountains of Hindu Kush, but other rivers contribute also.A basalt hill, known as Mount Khajeh, rises beside the lakes and marshes of the basin.Torgay River
The Turgai River (also Torgai or Turgay; Kazakh: Торғай, Torǵaı; Russian: Тургай) is a river that flows in the Turgai Valley in Kazakhstan.The river is 825 km (513 mi) long, the surface of the drainage basin is 157,000 km2 (61,000 sq mi). Average water consumption is around 9 cubic meters/second. The Turgai disappears in the endorheic basin of Shalkarteniz.The valley occupies an erosion-tectonic basin in north-western Kazakhstan, between the Urals and Mugodzhar Hills in the west and the Kazakh Steppe in the east. In the north are dry steppes with semi-steppes in the south. Deposits of iron ore and other minerals occur in the basin.The Turgai Plateau crosses from south to north. The Thurgau Ubahan (tributary of the Tobol) along with all the rivers of in the Turgai valley have many lakes. This is where the Naurzumskyy reserve is located which connects the West Siberian Plain in the northern part of Kazakhstan Turan lowland.Whitewater Lake, Manitoba
Whitewater Lake is a lake in the Canadian province of Manitoba located between Boissevain and Deloraine. It is an endorheic basin and more marsh than lake. Whitewater Lake was previously called White Lake due to the color of the salt flats exposed during dry periods. Whitewater Lake covers approximately 22,000 acres on average and only reaches depths of about 2 metres (6.6 ft). The lake is fed by several small streams which flow into it from the Turtle Mountains but has no natural outflow.The alkaline lake was vulnerable to drought having dried up several times including 1857, 1913-1915, 1934-1940 and 1989-1992. In 1989 Ducks Unlimited Canada began partnering with Manitoba Conservation and other partners to enhance the sustainability of the lake, investing more than two million over the following years. Dikes and water control structures were added to the east side of the lake to ensure the permanency of the water even during dry years.As of 2016, Whitewater Lake was at a peak of 1633 ft which is five feet above the average long-term level. These high levels have seen the lake claim more farm land and resulted in significant erosion of the dike and park space structures on the lake's southeast side.Üüreg Lake
Üüreg Lake (Mongolian: Үүрэг нуур, Üüreg nuur) is a saline lake in an endorheic basin in western Mongolia, north-west of the Great Lakes Hollow, near the western edge of the Uvs Nuur basin. The Tsagaan river gorge Tsagaan Shuvuut Uul) lies on the west side of the lake.