Frequent Sahara Floods: An Explanation of Their Occurrence and Potential Negative Implications
Deserts, particularly the Sahara, are renowned for their vast, sandy terrain and scorching temperatures. But here's a wild fact - these harsh landscapes receive rainfall! In fact, the Sahara Desert averages a mere 0.5 millimeters of rainfall per year. While it may not rain every year, the desert can witness heavy downpours that lead to devastating flooding.
In September 2024, the northwestern part of the Sahara was hit by such a weather event when an extratropical cyclone passed through. This fate-sealing storm dumped a staggering 200 millimeters of rain on the area in just a couple of days, a feat that occurs once every three to five decades. Compared to American states that can receive up to 71 inches of rain annually, according to Statista, this deluge makes a tremendous impact in a region where rainfall is a rarity.
NASA's Terra satellite captured the floodwaters that filled the typically bone-dry lakes across northwest Algeria, Libya, southeast Morocco, and Tunisia. However, dramatic flooding like this doesn't happen often. Researchers analysing weather events over two decades (2000-2021) found only six occasions where the desert lakes were filled due to flooding.
Now, for a little weather trivia. The Sahara's desert climate is characterized by scarcity and sporadic rainfall. Southern desert regions like Libya experience low monthly rainfall, typically a few millimeters during the wettest months and just a few days of wetness annually. These infrequent rains make significant flooding events highly unusual. Nonetheless, sporadic heavy rainfall with flooding potential can occur in desert regions, albeit infrequently.
Despite a scarcity of data suggesting regular flooding in the northwest Sahara, existing climate projections predict persistent or intensifying dry conditions, with an increase in consecutive dry days in the northern regions bordering the desert. In other words, flooding in the Sahara remains a rare and unpredictable occurrence.
The weather event in September 2024, where an extratropical cyclone passed through the northwestern part of the Sahara, was a testament to the fact that heavy rainfall can occur in desert regions, although it's exceptionally rare. Such events, however, might become even more unpredictable as climate projections indicate persistent or intensifying dry conditions in the Sahara, potentially increasing the number of consecutive dry days in the northern regions.
