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
Luangwa River A tributary of the Shire River at the south end of the Great Rift Valley then cut back eastwards through the Chicao Trough and Zambezi Valley, capturing the southerly overspill of the Madumabisa Lake. This tributary became the Zambezi, which over millions of years captured the Kafue, Cuando and the upper Zambezi. Faulting lowered the land between the Luangwa Rift and the Zambezi Rift allowing Madumabisa Lake to drain out into the Zambezi in a channel which became the lower Luangwa River. The Luangwa Rift Valley and rivers within it form a natural barrier, with a very low population density.