Oasis

An oasis [. Oa zə ː ] (. AltGr ὄασις Oasis " inhabited place "; from the Egyptian, ancient Egyptian Waset " boiler ") is a vegetation patch in the desert, usually located near a spring, water hole or a wadi. Oases can vary greatly in size and character, from the small, surrounded by date palms pond to entire cities with established industrial and agricultural enterprises. The traditional form of economy, different cultures are combined in, is the oasis economy. A special form to obtain water are the qanats. Geographically oases are assigned as enclaves in otherwise unpopulated areas of the earth's surface the so-called Periökumene.

  • 3.1 Africa
  • 3.2 America
  • 3.3 Asia
  • 3.4 Australia

Oasis types

The oases are divided according to the origin of the water. There are groundwater oasis river water oasis, the spring water oasis oasis with artesian wells and the Foggara oasis.

River water oasis

The river water oasis is more of a " fake" oasis. A stranger River flows through an otherwise dry area, thereby enabling the colonization of an area of the desert. The best known is the Nile river oasis. It is typical that areas have produced ancient irrigated crops along the river oases (eg Egyptians, Sumerians, Moche ).

The river carries the water over a long distance from high rainfall areas. The water is used for irrigation. On the shore areas, there are then fertile soil.

Groundwater oasis

In groundwater oases, the water is transported from the nearest aquifer to the surface by means of a pump or a well. Some oases of the Sahara are groundwater havens and below sea level. Rainfall seep away at Atlas Mountains. They accumulate over an impermeable material. The groundwater oasis goes hundreds of kilometers far into the Sahara. It taps into the water on by a fountain.

Spring water oasis

When rains in the mountains, the water seeps into the soil until it hits a water-bearing and water-impermeable layer. In it continues to flow underground, until it re-enters the earth's surface in the desert.

Oasis with artesian well

Artificial oases on the basis of artesian wells have been created, for example, in southern Algeria. They are used, inter alia, the date cultivation.

Foggaraoase

The ground water of a near -lying (up to 30 km) mountain range is passed through tunnels over many kilometers to the oasis. In addition, tunnel with leading vertically upward air shafts are driven into the desert to take advantage of the in the tunnels condensed by cooling the incoming hot desert air humidity. In addition are the many tunnel for repairs very useful ( Kanat, Qanat ).

Deep wells

Fossil water is pumped from great depths with the aid of powerful pumps.

Ghout

On the edge of deserts ( ergs ) the groundwater is very close under the earth's surface. In funnel- like depressions ( Ghout ) Palm roots can reach groundwater.

Oasis economy

The oasis economy is a very intensive form of economy within the oases in the arid regions. Your typical feature is a three- division by the so-called Storied. At the lowest level of wheat, barley, millet, various types of vegetables, rice and fodder crops are grown. In the second level, low tree crops such as figs and pomegranates dominate. The third level consists of the date palms, the fruits of which serve the residents as a food source and as exports. In addition, oil and apricot trees are grown.

The water needed for the crop is in some areas but underground procured mostly in above-ground, open channels ( Seguias ) according to a strictly defined scheme distributed.

Oases were formerly supply sites for caravans and trading centers of the nomads and farmers who practiced a bartering in them. Since the end of the colonial era and the beginning of the oil and natural gas production, the oases have become less important. Accordingly, there are very few traditional havens today. A marginalization of their original population cause high workload, irrigation techniques, the exodus from the oases, sedentarization of nomadic peoples, the sinking of the trans-Saharan caravan traffic, the loss of significance of the date by changing consumer habits, as well as climate change and that caused by them decrease of water resources.

Some oases in North Africa, however, have experienced a structural change, which is due to the development of deeper water reserves. This allowed an intensification and expansion of agriculture and tourism. While earlier in the oasis because of its location just subsistence farming was possible and the date the only existing export, agricultural production has been now focused increasingly on the market.

The oasis settlements themselves have changed. They have become not only larger but have also shifted more to the edge of the oasis corridor. The reason for this is especially tourism, which significantly improved the economic situation of the population. Due to the change and with increasing demand for drinking water reserves of the oases are severely threatened and water is more in the oases and more scarce commodity.

Examples

Africa

  • Bahariyya, Egypt
  • Dakhla, Egypt
  • Djanet, Algeria
  • Draa Valley, Morocco
  • El Tour, Sinai (Peninsula)
  • Farafra, Egypt
  • Figuig, Morocco
  • Gaberoun, Libya
  • Ghardaia, Algeria
  • Kufra oasis, Libya
  • M'zab, Algeria
  • Nile valley and delta, Egypt ( 22,000 km ² the largest oasis in the world )
  • Ouargla, Algeria
  • Safsaf, Egypt
  • Siwa, Egypt
  • Skoura, Morocco
  • Tafilalet, Morocco
  • Tata, Morocco
  • Timimoun, Algeria
  • Tinerhir, Morocco
  • Tozeur, Tunisia
  • Twat, Algeria
  • Zerzura ( a mythical oasis in Libya or Egypt)

America

  • Fish Springs National Wildlife Refuge, United States of America
  • Huacachina, Peru
  • La Cienega, New Mexico, United States of America
  • The valley of Las Vegas, United States of America. Once an oasis in the Mojave Desert, it has turned into a big city with about 1.8 million inhabitants, the Las Vegas Strip is located.
  • Mulege, Baja California Sur, Mexico
  • San Ignacio, Baja California Sur, Mexico
  • San Pedro de Atacama, Chile
  • Twentynine Palms, California, United States of America
  • Warm Springs, Nevada, United States of America

Asia

  • Al - Hasa, the largest oasis in Asia, Saudi Arabia
  • Al- Qatif, Saudi Arabia, a large oasis on the coast of the Persian Gulf
  • Azraq, Jordan
  • En Gedi, Israel
  • Loulan, China
  • Miran, China
  • Niya China
  • Tabas, Iran
  • Turpan, China

Australia

  • Palm Valley, Central Australia
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