Satellite images taken by NASA’s OLI-2 (Operational Land Imager-2) on Landsat 9 captured the incredible moment Sebkha el Melah, a lake in the Sahara Desert, filled with water.
Satellite pictures dating back to September 29 show the rare natural phenomenon happening in the Algerian lake.
Large parts of northern Africa have seen extreme weather conditions bring in a torrent of rainfall, which caused multiple ephemeral lakes to fill.
As of October 16, water covered 191 square kilometres (74 square miles) to a depth of 2.2 meters (7.2 feet). Lake Sebkha el Melah was roughly one-third full, according to Moshe Armon, a senior lecturer at the Hebrew University of Jerusalem.
There have been hundreds of rainfall events covering the Algerian lake since 2000, yet only six produced enough water to begin filling it.
The filling of a Sahara Desert lake is a “rare, largely undocumented, transient phenomenon,” according to Joëlle Rieder in a 2024 study that detailed the frequency of refilling events at the lake since 2000.
Previous satellite observations show that water in Lake Sebkha el Melah can remain for years.
The last time it filled in 2008, it took four years to dry completely, meaning if there was no more heavy rainfall, the lake currently would take a year to evaporate.
For cyclones to develop enough rainfall to fill a lake, moist air needs to be pushed up over the mountains, a process called orographic lift.
However, the presence of water in the Sahara Desert wasn’t always such a rarity. Thousands of years ago, the African humid period saw a much wetter northern Africa.
Geological evidence shows that the desert was abundant with grasses, trees, and lakes as bodies of water expanded.
An increased annual rainfall was a main source of this, forming many rivers and wetlands across the area.
Throughout the years, changes in Earth’s axial tilt have caused the variation in wet and dry periods across the desert.