The waters of the Okavango are at their highest when the dry season is taking its toll on the wilderness. In fact it is during the rainy season that the delta is at its lowest levels for the year. This strange phenomenon is due to the rainfall patterns in the delta region and the catchment area of the rivers that provide the delta with water.
The Okavango basin receives, on average, less than 500mm of rain per annum, a relatively low rainfall figure when looking at the lush oasis that is the delta itself. In general the rainfall comprises less than a third of the annual water intake in the delta and is only enough to raise the water table. Only in exceptional rainfall years will the delta flood from the local rainfall.
Most of the water that floods the Okavango comes from 1700km away in the catchment area of the Angolan Highlands, a process that can take up to six months before the water reaches the delta itself. By the time the water reaches the delta the dry season is well advanced leading to the unique situation of flooded plains surrounding dry dusty islands.
The story of the Okavango is unique in Africa, but it is in the seasonal changes of the different regions of the delta where the true wonder lies.
The Okavango, a place of constant change, is the last resort of a once-great lake that was fed by the flow of mighty rivers such as the Zambezi. As the great Zambezi shifted course the great lake began to shrink and today the delta is all that is left of the great water body.
Signs that more often than not go unnoticed in the vast northern Botswana wilderness indicate the shrinking and constant changing of the delta over the years. Relics of floodplains of the past are sprawled across the mostly-uninhabited northern wilderness.