There is a sea in southwestern Libya. Yes, there is no water – it is called the Ubari Sand Sea, which is the Ubari Sand Sea. Even on the map, it looks like a huge ocean – the territory is visually different, with settlements located "on the shore" as if it were a real body of water. It is clear from the color alone that the sea is not filled with water, but with sand. However, there was once a lot of water that replaced this piece of sand.
Shahai Ubari
Yes, there is now a real desert here – almost no vegetation, eternal drought and rare oases. Scientists claim that the area, now known as Fezzan, was underwater about 200,000 years ago. It was a lake, and they temporarily named it Megafezzan.
It covers an area of 120,000 square kilometers, four times the size of Lake Baikal. Megafezzan is now considered the second largest lake on Earth after the Caspian Sea. However, according to the same theory, Africa has large amounts of water – it is believed that there is only a single network of lakes, including the same Lake Chad, which can reach an area of up to 1 million square kilometers at certain times.
The sand sea of Ubari and the settlements on the "coast"
Specifically, according to the same researcher, Megafezzan fed the same river system that doesn't exist now. And this lake has been around for a long time – at least, according to recent studies (mainly archaeological excavations), it disappeared about 3-4 thousand years ago, nothing more. Obviously, all dates can be questioned, but not even about them.
Interestingly, there are now about twenty oases on the territory of the Ubalysha Sea (about - because some are thought to have been lost, because there has been no water there for a long time) lakes, which are thought to be the remains or traces of that super large lake.
Estimated location of Megafezzan Lake and its river system
These oases themselves have become local attractions, just like desert oases, the only place for weary travelers to rest. Hotels are also being built near the current oasis, where tourists come to admire the water islands in the sandy sea.
Not all of them are the same – some are large, surrounded by palm trees and other plants, and even deep enough to attract the attention of divers (up to more than 30 meters). There are also real antiquities here – for example, the Gaberoun oasis attracts tourists because of the ruins of an ancient village on its shore.
Lake Cabellon, with an abandoned village on the shore
A popular lake called Umm el-Ma is the largest on the list of local oases and is considered the most beautiful. But, for example, Lake Mandala, although it is also considered beautiful, it dries up in the summer and only fills with water in the winter, and even then, it is not always the case.
All local oases have one thing in common – they are very salty, and in some places the water is almost the same as the water of the Dead Sea. Water in some oases also changes color due to algae. However, all this only attracts the attention of tourists - you can admire all the oases, mainly not to drink water from these lakes, which will definitely not quench your thirst.
Lake um Elma
The reason for the salinity of the water in these oases is understandable – as we have seen, the water evaporates violently and some oases even dry up periodically, so the concentration of salt increases every year. None of the lakes in the Ujalisha Sea are fed by river water (there are few and far between here, and they all dry up), so their existence depends entirely on the water underground.
In general, the nature of oases implies this dependence, since by definition, an oasis is a place in the desert where some underground resource reaches the surface for some reason.
Lake Mandala – while paying attention to the height of the dunes behind
Thus, the drying up of oases depends not only on heat, or rather, changes in topography, but also on the state of the underground reservoirs that feed them.
As a result, the area where the oasis is located is usually lower in height than the surrounding desert – there may also be water beneath the desert, but it is deep. For example, the sand dunes of the Ubaly Sand Sea are particularly elevated by 400-500 meters above the height of some oases. But it turns out that the oases themselves "failed" a bit – which is why they were filled with water.
An oasis on a satellite map of the Ubaly Sand Sea
As we have already written in a story about green circles in the desert, all these underground reservoirs are remnants of ancient reservoirs and even glaciers, often sealed at deep depths. But they have one thing in common – the water doesn't stay inside, which means it's over if you take it from there.
The oasis that has truly disappeared over the past few decades is the result of the depletion of such underwater reservoirs. In the case of the UbalySha Sea, as in many other parts of the Sahara, the story is the same – technology allows for the active extraction of this water and agriculture for use by local authorities and people.
This is how fruits and vegetables are grown in the desert, creating fertile land with the help of the water under the desert.
Today in Libya, you can see the same green circle – a project called the Great Man-Made River is running in the country. Its essence is that, right in this area, underneath the Ubari Sand Sea, pipes are laid — water is pumped out of underground reservoirs and transported to other parts of the desert.
Needless to say, it also helps people survive in the here and now and end the future – according to all calculations, the water in natural underground storage facilities will last for 50-100 years.
The green circle near the "coast" of the Ubaly Sand Sea – a pipe of water extracted from the sand of the desert leads here
Right now, in many places, the water table is simply gradually declining – in the Sand Sea of Ubari, which is why there may soon be no water "island" left.