Zambezi the overflow of the Zambezi in the rainy season. The delta of the Zambezi is today about half as broad as it was before the construction of the Kariba and Cahora Bassa dams controlled the seasonal variations in the flow rate of the river. Before the dams were built seasonal flooding of the Zambezi had quite a different impact on the ecosystems of the delta from today as it brought nutritious fresh water down to the Indian Ocean coastal wetlands. The lower Zambezi experienced a small flood surge early in the dry season as rain in the Gwembe catchment and
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