Editing Oasis (section)

== Description ==
Oases develop in "[[Hydrology|hydrologically]] favored" locations that have attributes such as a high [[water table]], seasonal lakes, or blockaded [[wadi]]s.<ref>{{Cite journal |last=Gebel |first=Hans Georg K. |date=2013 |title=Arabia's fifth-millennium BCE pastoral well cultures: hypotheses on the origins of oasis life |url=https://www.jstor.org/stable/43782872 |journal=Proceedings of the Seminar for Arabian Studies |volume=43 |pages=111–126 |jstor=43782872 |issn=0308-8421 |access-date=2022-11-12 |archive-date=2022-11-12 |archive-url=https://web.archive.org/web/20221112045806/https://www.jstor.org/stable/43782872 |url-status=live }}</ref> Oases are made when sources of freshwater, such as underground rivers or [[aquifer]]s, irrigate the surface naturally or via man-made wells.<ref name=":5">{{Cite news|url=https://www.nationalgeographic.org/encyclopedia/oasis/|title=oasis|date=2011-06-10|work=National Geographic Society|access-date=2018-04-30|language=en}}{{Dead link|date=February 2025 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The presence of water on the surface or underground is necessary and the local or regional management of this essential resource is strategic, but not sufficient to create such areas: continuous human work and know-how (a technical and social culture) are essential to maintain such ecosystems.<ref name=":2">[http://hal.archives-ouvertes.fr/hal-00569337 Vincent Battesti, The Power of a Disappearance: Water in the Jerid region of Tunisia ''in'' B. R. Johnston ''et al.'' (eds), ''Water, Cultural Diversity & Global Environmental Change: Emerging Trends, Sustainable Futures?'', 2012, UNESCO/Springer, {{p.|77-96}}] {{Webarchive|url=https://web.archive.org/web/20181216031129/https://hal.archives-ouvertes.fr/hal-00569337 |date=2018-12-16 }}. {{ISBN|978-9400717732}}.</ref><ref name=":4">{{Cite journal|url=https://hal.archives-ouvertes.fr/hal-01154717|title=Resources and Appropriations: Back to the Jerid Oases (Tunisia) after the Revolution|first=Vincent|last=Battesti|date=May 28, 2015|journal=Études rurales|volume=2|issue=192|pages=153–175|via=HAL Archives Ouvertes|doi=10.4000/etudesrurales.9954|s2cid=126624438 |doi-access=free}}</ref> Some of the possible human contributions to maintaining an oasis include digging and maintaining wells, digging and maintaining canals, and continuously removing opportunistic plants that threaten to gorge themselves on water and fertility needed to maintain human and animal food supplies.<ref>Cutler, B.  Environmental History of the Maghreb, 1800–Present. ''Oxford Research Encyclopedia of African History.'' Retrieved 25 Jan. 2023, from https://oxfordre-com.wikipedialibrary.idm.oclc.org/africanhistory/view/10.1093/acrefore/9780190277734.001.0001/acrefore-9780190277734-e-983 .</ref> Stereotypically, an oasis has a "central pool of open water surrounded by a ring of water-dependent shrubs and trees…which are in turn encircled by an outlying transition zone to desert plants."<ref name="aeon">{{Cite web |last=Lawton |first=Rebecca |date=2015-11-06 |title=Palm trees amid the sand: the origins of the oasis fantasy |url=https://aeon.co/essays/palm-trees-amid-the-sand-the-origins-of-the-oasis-fantasy |access-date=2022-09-22 |website=Aeon Essays |language=en |archive-date=2022-09-22 |archive-url=https://web.archive.org/web/20220922032631/https://aeon.co/essays/palm-trees-amid-the-sand-the-origins-of-the-oasis-fantasy |url-status=live }}</ref>

Rain showers provide subterranean water to sustain natural oases, such as the [[Tuat]]. Substrata of impermeable rock and stone can trap water and retain it in pockets, or on long faulting subsurface ridges or volcanic dikes water can collect and percolate to the surface. Any incidence of water is then used by [[migrating bird]]s, which also pass seeds with their droppings which will grow at the water's edge forming an oasis. It can also be used to plant crops.

===Geography===
Oases in the [[Middle East]] and [[North Africa]] cover about {{convert|1000000|hectare|km2}}, however, they support the livelihood of about 10 million inhabitants.<ref name="Jaradat">{{cite web |last=Jaradat |first=Abdullah A. |title=Biodiversity of Date Palm |url=https://www.eolss.net/sample-chapters/c10/E1-05A-66.pdf |website=USDA-ARS |access-date=2022-09-22 |archive-date=2022-08-02 |archive-url=https://web.archive.org/web/20220802232437/https://www.eolss.net/sample-chapters/c10/E1-05A-66.pdf |url-status=live }}</ref> The stark ratio of oasis to desert land in the world means that the oasis [[ecosystem]] is "relatively minute, rare and precious."<ref name="aeon" />

There are 90 “major oases” within the Sahara Desert.<ref name=":5" /> Some of their fertility may derive from irrigation systems called ''[[foggaras]]'', ''khettaras'', ''lkhttarts'', or a variety of other regional names''.''<ref name="fao">{{Cite web |title=Oases Ecosystems |url=https://www.fao.org/3/az741e/az741e.pdf |website=FAO.org |access-date=2022-09-22 |archive-date=2024-09-23 |archive-url=https://web.archive.org/web/20240923070657/https://www.fao.org/3/az741e/az741e.pdf |url-status=live }}</ref><ref name="Yale">{{Cite web |last=Bryce |first=Emma |date=2016-12-12 |title=A Drive to Save Saharan Oases As Climate Change Takes a Toll |url=https://e360.yale.edu/features/a_drive_to_save_sahran_oases_as_climate_change_takes_a_toll_cop22 |access-date=2022-09-23 |website=Yale Environment 360 |language=en-US |archive-date=2022-09-23 |archive-url=https://web.archive.org/web/20220923221359/https://e360.yale.edu/features/a_drive_to_save_sahran_oases_as_climate_change_takes_a_toll_cop22 |url-status=live }}</ref>

In some oases systems, there is "a geometrical system of raised channels that release controlled amounts of the water into individual plots, soaking the soil."<ref name="Yale" />

[[File:Canal of irrigation.jpg|thumb|Irrigation canal within the [[Figuig]] Oasis in eastern [[Morocco]]]]

===History===
Oases often have human histories that are measured in millennia. Archeological digs at [[Ein Gedi]] in the Dead Sea Valley have found evidence of settlement dating to 6,000 BC.<ref>{{Cite web |title=Life in a Busy Oasis - Archaeology Magazine |url=https://www.archaeology.org/issues/340-1905/letter-from/7568-life-in-a-busy-oasis |access-date=2022-09-23 |website=www.archaeology.org |archive-date=2022-09-23 |archive-url=https://web.archive.org/web/20220923001805/https://www.archaeology.org/issues/340-1905/letter-from/7568-life-in-a-busy-oasis |url-status=live }}</ref> [[Al-Ahsa Oasis|Al-Ahsa]] on the Arabian Peninsula shows evidence of human residence dating to the [[Neolithic]].<ref>{{Cite web |date=2022-09-01 |title=Spring pool no.1 (Ain al Khudoud) and a water- lifting device, photographed by George Rendel, 1937 |url=https://content.ebscohost.com/ContentServer.asp?T=P&P=AN&K=158872037&S=R&D=f6h&EbscoContent=dGJyMNHX8kSeqLI40dvuOLCmsEqep7JSs6y4S7WWxWXS&ContentCustomer=dGJyMOzpsE2xqbNRuePfgeyx43zx |website=Geographical Magazine |access-date=2022-09-24 |archive-date=2022-09-24 |archive-url=https://web.archive.org/web/20220924150608/https://content.ebscohost.com/ContentServer.asp?T=P&P=AN&K=158872037&S=R&D=f6h&EbscoContent=dGJyMNHX8kSeqLI40dvuOLCmsEqep7JSs6y4S7WWxWXS&ContentCustomer=dGJyMOzpsE2xqbNRuePfgeyx43zx |url-status=live }}</ref>

[[Anthropology|Anthropologically]], the oasis is "an area of sedentary life, which associates the city [''medina''] or village [''[[ksar]]''] with its surrounding feeding source, the palm grove, within a relational and circulatory nomadic system."<ref name="biskra">{{Cite journal |last1=Hadagha |first1=Fatma Zohra |last2=Farhi |first2=Bourhane Eddine |last3=Farhi |first3=Abdallah |last4=Petrisor |first4=Alexandru Ionut |date=2018-12-29 |title=Multifunctionality of the oasis ecosystem. Case study: Biskra Oasis, Algeria |url=https://ijcua.com/index.php/ijcua/article/view/111 |journal=Journal of Contemporary Urban Affairs |volume=2 |issue=3 |pages=31–39 |doi=10.25034/ijcua.2018.4716 |s2cid=165113883 |issn=2475-6156 |doi-access=free |access-date=2022-09-22 |archive-date=2022-09-22 |archive-url=https://web.archive.org/web/20220922025708/https://ijcua.com/index.php/ijcua/article/view/111 |url-status=live }}</ref>

The location of oases has been of critical importance for trade and transportation routes in desert areas; caravans must travel via oases so that supplies of water and food can be replenished. Thus, political or military control of an oasis has in many cases meant control of trade on a particular route. For example, the oases of [[Awjila]], [[Ghadames]] and [[Kufra]], situated in modern-day [[Libya]], have at various times been vital to both north–south and east–west [[Trans-Saharan trade|trade in the Sahara Desert]]. The location of oases also informed the Darb El Arba'īn trade route from Sudan to Egypt, as well as the caravan route from the [[Niger River]] to [[Tangier]], Morocco.<ref name="aeon" /> The [[Silk Road]] "traced its course from water hole to water hole, relying on oasis communities such as [[Turpan]] in China and [[Samarkand]] in Uzbekistan."<ref name="aeon" />

According to the United Nations, "Oases are at the very heart of the overall development of peri-Saharan countries due to their geographical location and the fact they are preferred migration routes in times of famine or insecurity in the region."<ref name="fao" />

Oases in [[Oman]], on the [[Arabian Peninsula]] near the [[Persian Gulf]], vary somewhat from the Saharan form. While still located in an arid or semi-arid zone with a date palm overstory, these oases are usually located ''below plateaus'' and "watered either by springs or by [[Aflaj Irrigation Systems of Oman|''aflaj'']], tunnel systems dug into the ground or carved into the rock to tap underground aquifers." This rainwater harvesting system "never developed a serious salinity problem."<ref name="Jaradat" />

[[File:Oman-Oasis.jpg|thumb|Oasis in Oman]]
[[File:Khattara.png|thumb|Diagram of khattara system]]

===Palm Oasis===
In the drylands of southwestern North America, there is a habitat form called Palm Oasis (alternately Palm Series or Oasis Scrub Woodland) that has the native [[California fan palm]] as the overstory species.<ref name=":6">{{Cite web |last=Laudenslayer |first=William F. Jr. |title=Palm Oasis |url=https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=67356 |access-date=2022-09-22 |website=CDFW - California Wildlife Habitat Relationships System |archive-date=2024-09-23 |archive-url=https://web.archive.org/web/20240923070655/https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=67356 |url-status=live }}</ref> These Palm Oases can be found in [[California]], [[Arizona]], [[Baja California]], and [[Sonora]].<ref name=":6" />