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Oasis

earth science Maturity 11-13 Next article →

An oasis is a fertile area located within a desert or semi-desert environment.

Oasis and desert (49373993363)
Oasis and desert (49373993363)

These ecosystems are essential because they sustain plant life and provide habitats for animals. While they depend on natural water conditions, most oases are actually artificial. This means humans play a major role in creating or maintaining them. In geography, an oasis might also serve as a rest stop on a transportation route. Even if an area is not very green, it can be an oasis if humans maintain deep wells to access underground water.

Oases develop in locations that are hydrologically favored. This means they have specific features like a high water table or seasonal lakes. Sometimes, impermeable rock or stone can trap water in pockets. Water may also collect on subsurface ridges or volcanic dikes and percolate to the surface. Natural oases can also form when migrating birds visit water sources. These birds pass seeds in their droppings, which then grow at the water's edge. To maintain these areas, humans must perform continuous work. This includes digging and maintaining wells and canals. People must also remove opportunistic plants that might use up too much water and fertility.

Many oases use complex irrigation systems to manage their water. Some regions use systems called foggaras, khettaras, or lkhttarts.

Khattara
Khattara

These are often underground channels used to move water. In Oman, people use tunnel systems called aflaj to tap into underground aquifers. This rainwater harvesting system is very effective because it never developed a serious salinity problem. Other systems use a geometrical arrangement of raised channels. These channels release controlled amounts of water into individual plots to soak the soil.

Canal of irrigation
Canal of irrigation

Human history is deeply connected to these fertile spots. Archaeological evidence shows people settled at Ein Gedi in the Dead Sea Valley as early as 6,000 BC. There is also evidence of Neolithic residence at Al-Ahsa on the Arabian Peninsula. Anthropologically, an oasis is seen as a place of sedentary life. It connects a central village or city, known as a medina or ksar, to the surrounding palm groves. This creates a relationship between settled people and nomadic systems.

Because water is scarce, oases are vital for trade and transportation. Caravans must travel between oases to replenish their food and water supplies. This makes oases strategically important for political and military control. For example, the oases of Awjila, Ghadames, and Kufra in Libya were vital for Saharan trade. The Silk Road also relied on oasis communities like Turpan in China and Samarkand in Uzbekistan.

In the Middle East and North Africa, oases cover only about 1% of the land. However, they support the livelihoods of approximately 10 million inhabitants. There are 90 major oases located within the Sahara Desert.

Oases often use a layered planting method to create a microclimate. This is known as the oasis effect. The top layer consists of date palms, which are a major source of income and food.

Oman-Oasis
Oman-Oasis

These palms provide shade for a middle layer of trees, such as apricots, figs, olives, and peaches. The bottom layer contains market-garden vegetables and cereals like wheat, barley, and millet. This three-layer system reduces wind speed and increases humidity. Measurements show that this setup can reduce potential evapotranspiration by 30 to 50 percent.

Despite their importance, many oases face serious challenges. Climate change and decreasing groundwater levels put these systems at risk. In Morocco, two-thirds of the oasis habitat has been lost over the last 100 years due to heat and drought. Some historic oases in Egypt, such as Siwa and Kharga, have lost their flowing springs because of groundwater overuse. Modern water pumping techniques can also disrupt traditional management schemes. Maintaining the delicate balance of an oasis requires both natural water and careful human knowledge.

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🖼️ Images & Media (5)
File:Oasis and desert (49373993363).jpg
Oasis and desert (49373993363).jpg
File:Canal of irrigation.jpg
Canal of irrigation.jpg
File:Oman-Oasis.jpg
Oman-Oasis.jpg
File:Khattara.png
Khattara.png
File:Bled El Hadhar valley in Tozeur, Tunisia (Djerid Oasis).jpg
Bled El Hadhar valley in Tozeur, Tunisia...
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