Okavango

"Where all this water goes is a mystery", Aurel Schulz 1897.

The area was once part of Lake Makgadikgadi, an ancient Lake that dried up some 10,000 years ago. Today, the Okavango River has no outlet to the sea. Instead, it empties onto the sands of the Kalahari Desert, irrigating 15,000 km² of the desert. Each year some 11 cubic kilometres of water reach the delta. Some of this water reaches further south to create Lake Ngami.

The water entering the delta is unusually pure, due to the lack of agriculture and industry along the Okavango River. It passes through the sand aquifers of the numerous Delta islands and evaporates/transpirates by leaving enormous quantities of salt behind. These precipitation processes are so strong that the vegetation disappears in the center of the islands and thick salt crusts are formed.

The waters of the Okavango delta are subject to seasonal flooding, which begins about mid-summer in the north and six months later in the south (May/June). The water from the Delta is evaporated relatively rapidly by the high temperatures, resulting in a cycle of cresting and dropping water in the south. Islands can disappear completely during the peak flood, then reappear at the end of the season.