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.
Zambia tributaries rise in Angola's central highlands. The edge of the Cuando River floodplain (not its main channel) forms Zambia's southwestern border, and via the Chobe River that river contributes very little water to the Zambezi because most is lost by evaporation. Two of the Zambezi's longest and largest tributaries, the Kafue and the Luangwa, flow mainly in Zambia. Their confluences with the Zambezi are on the border with Zimbabwe at Chirundu and Luangwa town respectively. Before its confluence, the Luangwa River forms part of Zambia's border with Mozambique. From Luangwa town, the Zambezi leaves Zambia and flows into Mozambique, and