Lake in the heart of the Sahara Desert
In the extremely arid region of Northern Chad, where the average annual rainfall is barely more than 2 millimeters, is a chain of 18 lakes "Unianga." lake depends on underground water flows that were formed here a long time ago, when the climate was much Saharan more humid.
About 10 thousand years ago, this area was the only large lake in the tens of kilometers long. As the climate in recent years has changed dramatically, the lake has decreased, while expanding dunes split it into several small ponds. 18 lakes - this is all that came to our days. This NASA photo taken Nov. 14, 2009: Lake Unianga located in the small pool at the foot of the sandstone cliffs where the ancient underground water flows. Despite the intense heat and the high percentage of evaporation, groundwater sources are strong enough to feed the lake water. This unique hydrological system is able to feed even the largest lakes in the world, if they were in a dry environment.
