Lakes of Ounianga
Lacs d'Ounianga
- UNESCO natural beauty
Interesting facts
- A sediment core drilled from the bed of Lake Yoa contained 10,940 annual layers in 16 metres of mud, a year-by-year archive of the Sahara drying out.
- Pollen in the Lake Yoa cores, studied by Stefan Kröpelin's team from the University of Cologne, shows the Sahara became desert gradually, through scrub and grassland phases.
- That slow transition challenged an earlier reading of ocean sediments off Mauritania, which had suggested the desert arrived abruptly within a few centuries.
- The freshwater lakes of Ounianga Serir shelter relict tropical fish, including the bichir Polypterus senegalus, stranded here since the Sahara was green.
- With at least six fish species, the Ounianga Serir lakes are considered to hold the richest fish fauna known anywhere in the Sahara.
- Lake Teli covers about 436 hectares, more than Lake Yoa, yet it is less than 10 metres deep, while Yoa plunges to more than 20 metres.
- People first settled around the lakes roughly 11,000 years ago, after the last ice age, growing crops and herding cattle while the region was still humid.
- The two lake groups lie about 40 km apart, and the protected World Heritage area covers roughly 628 square kilometres of desert.
Why it is worth it
In one of the driest places on Earth, where less than 2 mm of rain falls in a year, eighteen lakes lie scattered among rock and ochre dunes in northeastern Chad. The Lakes of Ounianga should not exist, and that is their wonder. Their water is fossil: it collected in a vast underground aquifer during the humid millennia when the Sahara was green, and it still seeps up into these basins today, replacing what the desert sun takes away.
The lakes fall into two main groups, Ounianga Kebir and Ounianga Serir, with their colours depending on chemistry and the algae living in them, ranging from deep blue and green to reddish tones. At Ounianga Kebir the water is strongly saline. Its largest lake, Yoa, covers around 3.5 square kilometres and loses a column of water about six metres deep to evaporation each year; only algae and microorganisms survive in its brine, yet the aquifer keeps it full.
Ounianga Serir works differently and more surprisingly. Here a string of lakes is separated by narrow dune barriers, and most of them stay fresh. The largest, Lake Teli, sits slightly lower and evaporates faster, drawing water through the sand from its neighbours, so that salt collects in one lake while the others remain sweet. Floating mats of reeds cover a large part of the freshwater lakes, their intense green set against open blue water, and they in turn slow evaporation.
People lived here long before the desert closed in: archaeologists have found traces of settlement from the African humid period, including sand barriers built between roughly 7,500 and 5,000 years ago. Inscribed on the World Heritage List in 2012, the lakes remain one of the most remote and least-visited natural wonders of the Sahara.
Getting there
The lakes lie in Chad's Ennedi region, about 200 km in a straight line from the oasis town of Faya-Largeau. The nearest international airport within Chad is N'Djamena International Airport (NDJ), roughly 970 km away; Kufra Airport (AKF) in Libya is closer on the map but is not a practical approach. Visits are made overland by four-wheel-drive on desert tracks, usually with organised expeditions that combine Ounianga with Faya and the Ennedi plateau.
On these lists
From the encyclopaedia
The Lakes of Ounianga is a series of lakes in the Sahara Desert, occupying a basin in the mountains of West Tibesti and Ennedi East in north-eastern Chad. It was added as a UNESCO World Heritage site in 2012.
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