The Lakes of Ounianga

Eighteen lakes in a desert that gets 2 mm of rain

Eighteen lakes sit in the middle of the Sahara, in a place that gets less than two millimetres of rain a year. They are fed by groundwater, not weather, and UNESCO's citation calls them eighteen interconnected lakes, a single hydrological system spread across the desert.

They fall into two groups about 40 kilometres apart, in the Ennedi region of north-eastern Chad, and the two behave completely differently. Ounianga Kebir has four lakes. The largest, Yoan, covers 358 hectares and runs 27 metres deep, and its water is so saline that nothing lives in it but algae and microorganisms. Ounianga Serir has fourteen, separated from each other by sand dunes, and several of those hold high quality fresh water with real aquatic fauna in it.

The reason for that difference is the best thing on the site. Floating reeds cover almost half the surface of the Serir lakes, and by covering the water they cut evaporation. In a hyper-arid desert that shading is the difference between a lake that concentrates itself into brine and one that stays drinkable. Lake Teli has the largest surface of them all at 436 hectares while being less than ten metres deep, which in that climate ought to be a recipe for disappearing, and it does not.

The whole site covers 62,808 hectares and UNESCO listed it in 2012, describing an exceptional natural landscape of great beauty with striking colours and shapes. That is unusually flowery language for a World Heritage citation, and looking at the lakes it is hard to argue with.