What Causes an Oasis in the Desert?

Michael Anissimov

An oasis is a fertile spot in the middle of a desert, an island of life in an ocean of temperature extremes. Any oasis always contains one or more springs. Oases make it possible to survive long treks through the desert. In large deserts such as the Sahara, towns cluster around sources of water such as oases and rivers.

A desert.
A desert.

What causes an oasis? An oasis is actually a spot in the desert where the elevation is low enough that the water table is right underneath the surface, resulting in the presence of springs. Even in a desert, it rains occasionally, and this produces a water table just above the bedrock, usually several hundred feet below the surface. Sand is very porous, so most water runs right through it and down to the bedrock.

Dust storms can move great amounts of sand, making an oasis possible.
Dust storms can move great amounts of sand, making an oasis possible.

Deserts consist of many millions of tons of sand. There is only one natural force capable of moving it in appreciable amounts – the wind. Although, in an average dust storm, a ten cubic feet (3.05 cubic meters) of air only hold about an ounce of sand, a cubic mile (1.6 cubic km) of air can move about 4,600 tons of it, leading to appreciable erosion. A severe storm is capable of moving as much as 100 million tons of sand and dust.

Want to automatically save time and money month? Take a 2-minute quiz to find out how you can start saving up to $257/month.

In certain areas where large quantities of sand are moved by storms, erosion burrows all the way down to the water table, putting it just beneath the surface. Seeds planted in the ground there are capable of sprouting and extending roots into the moist land, producing an oasis.

Sometimes, the oasis produced by the wind can be very large when vast tracts of desert are wiped clean by storms. The great Kharga oasis in the Sahara, for example, is over 100 miles (161 km) long and 12 to 50 miles (19.3 to 80.5 km) in width. The oasis was produced when erosion caused the margins of a great depression to sink down to the water table.

Dry, cracked earth in a desert.
Dry, cracked earth in a desert.

You might also Like

Discussion Comments


An oasis is big, and prosperous, like a spring.


What does an oasis need to survive?


What is the average life span of oases?

It seems like if one storm can move that much sand, and the movement of sand is what creates an oasis in the first place that the movement of sand could also cover an oasis.

As such, it makes me wonder if there is an average life span to an oasis or if this is not a real issue at all. After all, it could be a figment of my highly active imagination that this could happen in the first place!


No, there are also oasis in the middle of oceans and rivers.


in the desert it is important to find an oasis, because that is the only place for shelter, and water.


Yes, because why would you need an oasis if there are rivers and other sources of water, a.k.a., not a desert?


so, you just sink a hole anywhere in a desert, until you reach 'your bedrock', and whoa - the water is there? good for you, sell you knowledge to the Emirates :)


Is oasis only found in deserts?

Post your comments
Forgot password?