Zambezi km from the sea the Zambezi receives the drainage of Lake Malawi through the Shire River. On approaching the Indian Ocean, the river splits up into a delta. Each of the four primary distributaries, Kongone, Luabo and Timbwe, is obstructed by a sand bar. A more northerly branch, called the Chinde mouth, has a minimum depth at low water of 2 m at the entrance and 4 m further in, and is the branch used for navigation. 100 km further north is a river called the Quelimane, after the town at its mouth. This stream, which is silting up, receives
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