Salar de Uyuni
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Salar de Uyuni (also referred to as "Salar de Tunupa")<ref>Template:Cite web</ref> is the largest salt flat (dry lake bed) in the world, with an area of approximately of Template:Convert.<ref name="NASA2019">Template:Cite web</ref><ref>Template:Cite book</ref> It is situated in southwestern Bolivia, within the Daniel Campos Province of the Potosí Department, near the crest of the Andes Mountains, at an elevation of Template:Convert above sea level.<ref name=britannica>Template:Cite encyclopediaTemplate:Dead link</ref>
The Salar was formed as a result of transformations between several prehistoric lakes that existed around forty thousand years ago but had all evaporated over time.Template:R It is now covered by a few meters of salt crust, which has an extraordinary flatness with the average elevation variations within one meter over the entire area of the Salar. The crust serves as a source of salt and covers a pool of brine, which is exceptionally rich in lithium. The large area, clear skies, and exceptional flatness of the surface make the Salar ideal for calibrating the altimeters of Earth observation satellites.<ref name="nature2">Template:Cite journal</ref><ref name="geo">Template:Cite journal</ref><ref name="refl">Template:Cite journal</ref><ref>Template:Cite news</ref><ref name=ieee>Template:Cite journal</ref> Following rain, a thin layer of dead calm water transforms the flat into the world's largest mirror, Template:Convert across.<ref>Template:Cite news</ref>
The Salar serves as the major transport route across the Bolivian Altiplano and is a prime breeding ground for several species of flamingos. Salar de Uyuni is also a climatological transitional zone since the towering tropical cumulus congestus and cumulonimbus incus clouds that form in the eastern part of the salt flat during the summer cannot permeate beyond its drier western edges, near the Chilean border and the Atacama Desert.Template:Citation needed
The Salar has been used as a filming location for movies such as The Fall (2006), Salt and Fire (2016), The Unseen (2017), Star Wars: The Last Jedi (2017),<ref>Template:Cite web</ref><ref>Template:Cite web</ref> and several others.
Name
Salar means salt flat in Spanish. Uyuni originates from the Aymara language and means a pen (enclosure); Uyuni is a surname and the name of a town that serves as a gateway for tourists visiting the Salar. Thus Salar de Uyuni can be loosely translated as a salt flat with enclosures, the latter possibly referring to the "islands" of the Salar; or as "salt-flat at Uyuni (the town named 'pen for animals')".Template:Citation needed
Aymara legend tells that the mountains Tunupa, Kusku, and Kusina, which surround the Salar, were giant people. Tunupa married Kusku, but Kusku ran away from her with Kusina. Grieving Tunupa started to cry while breastfeeding her son. Her tears mixed with milk and formed the Salar. Many locals consider the Tunupa an important deity and say that the place should be called Salar de Tunupa rather than Salar de Uyuni.<ref name="trav12">Template:Cite book</ref>
Formation, geology, and climate
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The Salar de Uyuni is part of the Altiplano of Bolivia in South America. The Altiplano is a high plateau, which was formed during uplift of the Andes mountains. The plateau includes fresh and saltwater lakes as well as salt flats and is endorheic.<ref name="nasa">Template:Cite web</ref>
The geological history of the Salar is associated with a sequential transformation between several vast lakes. Some 30,000 to 42,000 years ago, the area was part of a giant prehistoric lake, Lake Minchin. Its age was estimated by radiocarbon dating shells from outcropping sediments and carbonate reefs and varies between reported studies. Lake Minchin (named after Juan B. Minchin of Oruro)<ref>Template:Cite journal</ref> later transformed into Paleo Lake Tauca having a maximal depth of Template:Convert, and an estimated age of 13,000 to 18,000 or 14,900 to 26,100 years, depending on the source. The youngest prehistoric lake was Coipasa, which was radiocarbon dated to 11,500 to 13,400 years ago. When it dried, it left behind two modern lakes, Poopó and Uru Uru, and two major salt deserts, Salar de Coipasa and the larger Salar de Uyuni. Salar de Uyuni spreads over 10,582 km2, which is roughly 100 times the size of the Bonneville Salt Flats in the United States. Lake Poopó is a neighbor of the much larger Lake Titicaca. During the wet season, Titicaca overflows and discharges into Poopó, which in turn, floods Salar De Coipasa and Salar de Uyuni.<ref name="nature">Template:Cite journal</ref>
Lacustrine mud that is interbedded with salt and saturated with brine underlies the surface of Salar de Uyuni. The brine is a saturated solution of sodium chloride, lithium chloride, and magnesium chloride in water. It is covered with a solid salt crust varying in thickness between tens of centimeters and a few meters. The center of the Salar contains a few islands, which are the remains of the tops of ancient volcanoes submerged during the era of Lake Minchin. They include unusual and fragile coral-like structures and deposits that often consist of fossils and algae.<ref name="trav1">Template:Cite book</ref>
Climate
The area has a relatively stable average temperature with a peak at Template:Cvt in November to January, and a low of Template:Cvt in June. The nights are cold all through the year, with temperatures between Template:Convert. The relative humidity is rather low and constant throughout the year at 30% to 45%. The rainfall is also low at Template:Convert per month between April and November, but it may increase up to Template:Convert in January. However, except for January, even in the rainy season the number of rainy days is fewer than 5 per month.<ref name="ieee" />
Economic influence
Located in the Lithium Triangle, the Salar contains a large amount of sodium, potassium, lithium and magnesium (all in the chloride forms of NaCl, KCl, LiCl and MgCl2, respectively), as well as borax.<ref name="trav1" /> As of 2024, with an estimated 23 mln. t, Bolivia holds about 22% of the world's known lithium resources (105 mln. tons); most of those are in the Salar de Uyuni.<ref>Template:Cite news (other Lithium statistics from USGS)</ref>
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Lithium is concentrated in the brine under the salt crust at a relatively high concentration of about 0.3%. It is also present in the top layers of the porous halite body lying under the brine; however, the liquid brine is easier to extract, by boring into the crust and pumping out the brine.Template:Citation needed The brine distribution has been monitored by the Landsat satellite and confirmed in ground drilling tests. Following those findings, an American-based international corporation has invested $137 million to developing lithium extraction.<ref>Template:Cite book</ref> However, lithium extraction in the 1980s and 1990s by foreign companies met strong opposition from the local community. Locals believed that the money infused by mining would not reach them.<ref name="BBC_electric_car">Template:Cite news</ref> The lithium in the salt flats contains more impurities, and the wet climate and high altitude make it harder to process.<ref>Template:Cite web</ref>
No mining plant is currently at the site, and the Bolivian government does not want to allow exploitation by foreign corporations. Instead, it intends to reach an annual production of 35,000 t by 2023 in a joint venture with ACI Systems Alemania GmbH.<ref>Template:Cite news</ref><ref name="BBC_electric_car" /><ref name="ACISA">Template:Cite web</ref>
Salar de Uyuni is estimated to contain 10 billion tonnes (9.8 billion long tons; 11 billion short tons) of salt, of which less than 25,000 t is extracted annually. All miners working in the Salar belong to Colchani's cooperative. Because of its location, large area, and flatness, the Salar is a major car transport route across the Bolivian Altiplano, except when seasonally covered with water.<ref name="nasa" />
Tourism
Hotels
Salar de Uyuni is a popular tourist destination, and consequently a number of hotels have been built in the area. Due to lack of conventional construction materials, many of them are almost entirely (walls, roof, furniture) built with salt blocks cut from the Salar. The first such hotel, named Palacio de Sal, was erected in 1993–1995<ref name="lick2">Template:Cite web</ref><ref name="lick1">Template:Cite web</ref> in the middle of the salt flat,<ref name="lick3">Template:Cite webTemplate:Dead link</ref><ref name="book1">Template:Cite book</ref> and soon became a popular tourist destination.<ref name="ng">Template:Cite web</ref> However, its location in the center of a desert caused sanitation problems, as most waste had to be collected manually. Mismanagement caused serious environmental pollution and the hotel had to be dismantled in 2002.<ref>Template:Cite book</ref><ref name="german">Template:Cite web</ref>
Around 2007, a new hotel was built,<ref name="ng" /> under the name Palacio de Sal, in a new location at the eastern edge of Salar de Uyuni, 25 km away from the town of Uyuni.<ref name="book1" /> The sanitary system has been restructured to comply with the government regulations.<ref name="lick2" /> The hotel has a dry sauna and a steam room, a saltwater pool and whirlpool baths.<ref>Template:Cite web</ref>
Train cemetery
One major tourist attraction is an antique train cemetery. It is Template:Convert outside Uyuni and is connected to it by the old train tracks. The town served in the past as a distribution hub for the trains carrying minerals en route to Pacific Ocean ports. The rail lines were built by British engineers arriving near the end of the 19th century and formed a sizeable community in Uyuni. The engineers were invited by the British-sponsored Antofagasta and Bolivia Railway Companies, now Ferrocarril de Antofagasta a Bolivia. The rail construction started in 1888 and ended in 1892. It was encouraged by Bolivian President Aniceto Arce, who believed Bolivia would flourish with a good transport system, but it was constantly interrupted by the local Aymara indigenous Indians who saw it as an intrusion into their lives. The trains were mostly used by the mining companies. In the 1940s, the mining industry collapsed, partly because of mineral depletion. Many trains were abandoned, producing the train cemetery. There are proposals to build a museum from the cemetery.<ref name="trav1" />
Incidents
Multiple fatal incidents have occurred at the salt flat as a result of poorly maintained vehicles, untrained drivers, speeding, a disregard for the inhospitable conditions, and lack of regulation for tour companies. A total of 16 reported accidents have happened with 30+ deaths in total.<ref>Template:Cite web</ref>
Satellite calibration
As the largest salt flat on Earth, the Salar de Uyuni is widely regarded as one of the most effective natural calibration sites for Earth-observing satellites.<ref>Template:Cite journal</ref> Its exceptionally high albedo, which reflects the majority of incoming sunlight, together with its vast, uniform terrain, makes it uniquely well-suited for remote sensing applications.<ref>Template:Cite journal</ref> Located at an altitude of Template:Convert above sea level, the salar offers stable emissivity and minimal radio frequency interference, providing space‐agencies and remote sensing scientists with ideal conditions for calibrating both radar and optical sensors.<ref>Template:Cite web</ref> Across its Template:Convert surface, the elevation variation is less than Template:Convert relative to the Earth's circumference. Collectively, these features make the Salar de Uyuni approximately five times more effective for satellite calibration than the surface of the open ocean.<ref name="gpsdaily">Template:Cite news</ref><ref>Template:Cite book</ref><ref>Template:Cite journal</ref>
In September 2002, NASA's ICESat-2 mission conducted extensive GPS surveys over the salar to support the calibration of its laser altimeters and improve their capability to produce ground‐truth digital elevation models with centimeter‐level (Template:Sfrac inch) accuracy.<ref>Template:Cite journal</ref> Similar missions have been conducted over the Salar de Uyuni for radiometric calibration, where the Landsat-5 satellite's Thematic Mapper (TM) was calibrated “in-flight” by using the salar as a radiometrically stable target, particularly in the visible and near-infrared bands.
In April 2014, the European Space Agency’s (ESA) Sentinel‑1A satellite surveyed the salar a few weeks after its launch as part of the Copernicus programme. The mission focused on calibrating radar-based measurements of surface topography. In 2010, ESA launched the CryoSat-2 mission to monitor variations in polar ice thickness and global sea levels. As part of its validation strategy, CryoSat-2 has relied on the salar, where its Interferometric synthetic-aperture radars (InSAR) capabilities were reinstated to enhance the precision of altimetric observations.<ref>Template:Cite web</ref> In February 2024, the Copernicus Sentinel-3B mission conducted calibration activities over the salar for its Synthetic Aperture Radar Altimeter (SRAL).<ref>Template:Cite journal</ref>
Flora and fauna
The Salar is virtually devoid of any wildlife or vegetation. The latter is dominated by giant cacti (Echinopsis atacamensis pasacana, Echinopsis tarijensis, etc.). They grow at a rate of about 1 cm/a to a height of about Template:Convert. Other shrubs include Pilaya, which is used by locals to cure catarrh, and Thola (Baccharis dracunculifolia), which is burned as a fuel. Also present are quinoa plants and queñua bushes.<ref name=trav1/>
Every November, Salar de Uyuni is the breeding ground for three South American species of flamingo feeding on local brine shrimps: the Chilean, Andean, and rare James's flamingos. About 80 other bird species are present, including the horned coot, Andean goose, and Andean hillstar. The Andean fox, or culpeo, is also present, and islands in the Salar (in particular Incahuasi Island) host colonies of rabbit-like viscachas.<ref name=trav1/>
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A part of Incahuasi Island inside the Salar, featuring giant cacti
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Bolivian vizcacha
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Andean flamingos in the Laguna Colorada, south of the Salar
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Vicuñas near the Salar De Uyuni 2017
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Gallery
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Salar de Uyuni 2013
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Piles of salt at the Salar
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Llamas in the Salar
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Reflection on the Salar de Uyuni
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Sky reflections at sunset
See also
References
External links
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