During the Ice Age, streams flowed into mega-lake Chad there in an endorheic basin (no outflow) from all directions, but since the Ice Age ended, almost all the water is from the east down the Chari river sourced in the Karre mountains of the Central African Republic at 5,000 foot elevations receiving sixty inches of rain per year. The lake now is usually about twenty miles by twenty miles in area with many islands, a shallow lake its deepest about thirty feet, but during the Ice Age it was about thirty times larger and twice as deep, hundreds of miles across with no islands.
