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 term "Sena River" ("Rio de Sena"), a reference to the Swahili (and later Portuguese) upriver trade station at Sena. In 1752, the Zambezi delta, under the name "Rivers of Sena" ("Rios de Sena") formed a colonial administrative district of Portuguese Mozambique. But common usage of "Zambezi" led eventually to a royal decree in 1858 officially renaming the district "Zambézia". The Zambezi region was known to medieval geographers as the Empire of Monomotapa, and the course of the river, as well as the position of lakes Ngami and Nyasa, were given broadly accurately in early maps. These were probably constructed from