Luangwa River ago, there was no way out and the Luangwa Rift filled with a Rift Valley Lake called the Madumabisa Lake, which rivalled Lake Malawi in size. The water of the lake overflowed in a river to the south-west, towards what is now the Kalahari, where it combined with the Okavango, Upper Zambezi, Cuando and Kafue rivers, emptying into the Limpopo River and flowing to the Indian Ocean. Several geological events combined to produce the current river systems. Faulting produced another graben just to the south of the Luangwa Rift, and running east-west: the Zambezi Rift Valley and the Chicoa Trough.
Zambezi most is lost through evaporation in its swamp systems. The 1940s and 1950s were particularly wet decades in the basin. Since 1975, it has been drier, the average discharge being only 70% of that for the years 1930 to 1958. Up to the Late Pliocene or Pleistocene (more than two million years ago), the Upper Zambezi river used to flow south through what is now the Makgadikgadi Pan to the Limpopo River. The change of the river course is the result of epeirogenic movements that uplifted the surface at the present-day water divide between both rivers. Meanwhile, east, a western